Page 1 AT&T 555-025-201 DEFINITY Communications System ® Network and Data Connectivity...
Page 3 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ A AB BO OU UT T T TH HI IS S D DO OC CU UM ME EN NT T PREREQUISITE SKILLS AND KNOWLEDGE DOCUMENT ORGANIZATION HOW TO MAKE COMMENTS ABOUT THIS DOCUMENT 1 1. . I IN NT TR RO OD DU UC CT TI IO ON N T TO O C CO ON NN NE EC CT TI IV VI IT TY Y TRANSMISSION TYPES ANALOG TRANSMISSION DIGITAL TRANSMISSION...
Page 4: Table Of Contents
CONTENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ MULTIPLEXING OUTSIDE THE SWITCH Multiplexing onto T1 Trunks Compressing the Signal Altering Channel Assignments on T1 Trunks Getting the Signal Ready for the Central Ofﬁce Changing the Transmission Medium from Metallic to Fiber-Optic Multiplexing with Microwave Demultiplexing STATISTICAL MULTIPLEXING...
Page 5 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Internal Dial Plan Auxiliary Call Information Automatic Alternate Routing Automatic Route Selection NETWORK ADMINISTRATION PRIVATE NETWORK TRUNKS NETWORKING FEATURE PARAMETERS 3 3. . T TA AN ND DE EM M T TI IE E T TR RU UN NK K N NE ET TW WO OR RK KS S INTERACTIONS WITH OTHER NETWORKS 4 4.
Page 6 CONTENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Automatic Route Selection ETN INTERACTIONS WITH OTHER NETWORKS Extension Number Portability Clusters Software-Deﬁned Network Release Link Trunk Networks — CAS and ACD Distributed Communications System Clusters Main-Satellite/Tributary Networks ENGINEERING CONSIDERATIONS 6 6. . D DI IS ST TR RI IB BU UT TE ED D C CO OM MM MU UN NI IC CA AT TI IO ON NS S S SY YS ST TE EM M ( (D DC CS S) ) DCS CLUSTERS DCS LINKS Tie Trunks...
Page 7 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Parallel vs. Serial Transmission Speed Type of Communications Channel SPECIAL DATA FEATURES Terminal Dialing Data Call Setup From a Voice Terminal Computer Dialing Data Hot Line Data Protection Data Privacy Data Restriction Data Only Off-Premises Extension 8 8.
Page 8 viii CONTENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ The Communication System as a LAN Backup PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS PUBLIC DATA NETWORKS Packet-Switched Public Data Networks Circuit-Switched Public Data Networks PRIVATE DATA NETWORKS Terrestrial Private Data Network Links Satellite Private Data Network Links TELEMARKETING HOST CONNECTIONS THE ISDN GATEWAY...
Page 9 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ USE OF GENERIC 2 AS A SYSTEM CLOCK REFERENCE USE OF GENERIC 1 AS A SYSTEM CLOCK REFERENCE C C. . T TR RU UN NK KI IN NG G T TE ER RM MS S A AN ND D C CA AP PA AB BI IL LI IT TI IE ES S D D.
Page 10 CONTENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Figure 1-1. Analog-to-Digital Conversion Figure 1-2. Transmission States for Voice Communication Figure 1-3. Transmission States for Data Transmission Figure 1-4. Time Slot Figure 1-5. Alternating Mark Inversion Figure 1-6. Example of B8ZS Line Coding Figure 1-7.
Page 11 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Figure 6-3. Direct Link DCS Connections Figure 6-4. Minimized Link Connections Figure 6-5. DCIU/PI Linkage in a DCS Cluster Figure 6-6. Short Haul Analog Signaling: System 75/G1 to System 75/G1 Via DSU Figure 6-7. Long Haul Analog Signaling: System 75/G1 to System 75/G1 Via Modem Figure 6-8.
Page 12 CONTENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Figure 8-9. Common ISN Conﬁguration Figure 8-10. LAN-to-LAN Connections Through the Switch Figure 8-11. X.25/StarGROUP Connectivity Figure 8-12. LAN/SNA Connectivity Figure 8-13. Packet Service ACCUNET Figure 8-14. Public Switched Data Network with Robbed Bit Facilities (Mode 1) Figure 8-15.
Page 13 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Figure B-11. External and Internal Reference Levels Figure B-12. Nonpublic Network without Digital Switches Figure B-13. Proper Use of Backup Facilities Figure B-14. Improper Use of Backup Facilities Figure B-15. Optimal Diverse Routing Figure B-16. Less Than Optimal Diverse Routing Figure B-17.
Page 14 CONTENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table 1-1. Terminal/Port Compatibility Table 1-2. Trunk Port Types Table 1-3. Protocol States for Data Communication Table 1-4. Physical-Layer Protocol vs. Character Code Table 1-5. DMI Mode vs. Character Code Table 1-6. Signal-Inversion Requirements Table 1-7.
Page 15 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table 8-8. Requirements for PBX-to-PBX Private Network Spectrum Connections Table B-1. SCS References Switches Table D-1. Some CCITT Digital Standards Table D-2. Some CCITT Analog Standards Table D-3. Some CCITT ISDN Standards Table D-4. Some Well-Known Protocol Standards Table D-5.
Page 16 CONTENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 17: About This Document
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ This document explains how to arrange two or more communications systems in a network. It also tells how to use your communications system to connect one data communications device or network to another device or network. This document is for AT&T sales teams and customers who are responsible for: Designing telecommunications networks Interfacing data processing devices or networks through a communications system...
Page 18 xviii ABOUT THIS DOCUMENT _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ PART I Chapter 2 — Communications System Networking — An Overview— Introduces the networking software packages that are used to implement a PBX network. Included is a matrix that maps node administration to the tools used given the type of switch and switch version.
Page 19 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ HOW TO MAKE COMMENTS ABOUT THIS DOCUMENT Reader comment cards are in the back of this document. While we have tried to make this document ﬁt your needs, we are interested in your suggestions for improving it and urge you to ﬁll one out. If the reader comment cards have been removed from this document, please send your comments to: AT&T Technical Publications Department...
Page 20 ABOUT THIS DOCUMENT _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 21 1. INTRODUCTION TO CONNECTIVITY _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ This book explains two aspects of communicating through a business communications system: Part I, Communications System Networking, explains how to arrange two or more communications systems in a network so that they communicate with each other efﬁciently and cost effectively. Part II, Data Connectivity, describes the ﬂow of data both within and between communications systems.
Page 22 INTRODUCTION TO CONNECTIVITY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 23: Transmission Types
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Both analog and digital transmission can be used to carry information across telephone lines and data links. ANALOG TRANSMISSION Analog transmission carries information as continuously varying electrical waves. Variables like the wave amplitude, phase, and frequency impart the information contained in the signal. Analog transmission can carry both voice and data.
Page 24: Figure 1-1. Analog-To-Digital Conversion
TRANSMISSION TYPES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ 1. Original signal 2. PAM pulses 3. PCM pulses 4. PCM output 011001110001011110100 Adapted from: Data and Computer Communications, by William Stallings, Macmillan Publishing Co., N.Y., 1988 Figure 1-1. Analog-to-Digital Conversion...
Page 25: Analog Vs. Digital
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Voice: To carry voice over digital transmission facilities, analog voice signals must be converted into digital information. To do this, the voice signal is sampled 8000 times a second. The sample is encoded according to a process called pulse-code modulation or PCM. Pulse-code modulation is a four-step process (see ﬁgure 1-1).
Page 26 TRANSMISSION TYPES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ signals became feasible through the economic, operational, and reliability features of solid-state electronics. In 1962, the Bell System established the ﬁrst commercial use of digital transmission when the ﬁrst T1 carrier system went into operation in a Chicago area exchange. By 1985, 50% of the country’s exchange- area trunks were T-carrier digital facilities.
Page 27: Voice Transmission
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ When you plan a communications network, there are certain rules that you cannot violate: Analog signals cannot be carried over digital facilities without ﬁrst being converted to digital. Digital signals cannot be carried over analog facilities without ﬁrst being converted to analog. Digital communication must conform to a particular protocol.
Page 28: Figure 1-2. Transmission States For Voice Communication
TRANSMISSION STATES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DIGITAL VOICE 4 3 2 TERMINAL 7 6 5 * # 0 9 8 DIGITAL VOICE 4 3 2 TERMINAL 7 6 5 * # 0 9 8 DIGITAL VOICE 4 3 2 TERMINAL 7 6 5 * # 0 9 8...
Page 29: Table 1-1. Terminal/Port Compatibility
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Incoming digital-trunk calls to a digital switch need no conversion since the call is already PCM encoded. Incoming digital-trunk calls to analog switches are converted outside the switch at a D4 channel bank. In these cases, the digital trunk terminates at the D4 channel bank. From the D4 channel bank, incoming calls are forwarded to the switch via analog trunks.
Page 30: Table 1-2. Trunk Port Types
1-10 TRANSMISSION STATES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Signal Type Analog Auxiliary Digital * Universal modules are available only on the G2 switch. From a digital switch, the voice signal, which is represented in the switch as digital PCM code, is converted to analog via a codec built into the analog line or trunk circuit pack.
Page 31: Data Transmission
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ DATA TRANSMISSION Because of the variety of protocols that can be used in data communication, data transmission has many more options than voice. To understand the processes that occur at the switch with data transmission, you must be familiar with the layers of protocol that the switch handles, understand some details about the protocols used at these layers, and know the points at which these protocols change.
Page 32: Figure 1-3. Transmission States For Data Transmission
1-12 TRANSMISSION STATES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ ORIGINATING DATA MODULE DATA MODULE RS-232 ASCII MODEM RS-232 ANALOG ASCII RS-232 ADU PROT ASYNCH ASCII DATA MODULE RS-232 ASCII Figure 1-3. Transmission States for Data Transmission SWITCH RAW BITS USER DEFINED VOICE GRADE DATA USER DEFINED RAW BITS...
Page 33 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Protocols Used The following is a list of the protocols that are meaningful when you transmit data to and through the switch. The list is organized by protocol layers. As you read through the list, follow the protocol changes through the transmission paths shown in ﬁgure 1-3.
Page 34: Table 1-3. Protocol States For Data Communication
1-14 TRANSMISSION STATES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ types of trunk protocols (for example, primary rate interface [PRI] and 24th-channel signaling) use DS1 protocol at layer 1. (See the Trunking section of this chapter for an explanation of these trunk types.) Inside the switch, data transmission appears in one of two forms.
Page 35: Table 1-4. Physical-Layer Protocol Vs. Character Code
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Note that both the physical-layer protocol and the DMI mode used in the connection are dependent upon the type of 8-bit code used at layer 2 between the DTE and DCE. (See tables 1-4 and 1-5.) Table 1-4.
Page 36 1-16 TRANSMISSION STATES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DCP-line port. The only caveat is that the destination data module must be set for mode-2 DMI communication. (See appendix D for a discussion of DMI modes.) Voice-grade data can be carried over a DS1 facility as long as the destination DCE is a modem compatible with the originating modem.
Page 37: Figure 1-4. Time Slot
MULTIPLEXED COMMUNICATION _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ As signals are transmitted away from the switch and onto a public or private network, multiplexed communication becomes an option. Multiplexed communication results from the interleaving of signals from multiple circuits into a single communications path. For transmissions with the same destination, it is an economic alternative to using multiple single-trunk transmission paths.
Page 38 1-18 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Time-division multiplexing can be bit interleaved or byte interleaved. With bit interleaving, the time slot assigned to a particular channel is one bit long and the channel recurs every 15.5 microseconds over a DS1 link.
Page 39: Line Coding
1-19 MULTIPLEXED COMMUNICATION _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Line Coding Line coding is the pattern that data assumes as it is propagated over a communications channel. Governing line coding is a set of parameters that must be deﬁned for all digital transmissions. These transmission parameters specify the voltage level and patterns in which 1s and 0s can appear on the line.
Page 40: Figure 1-6. Example Of B8Zs Line Coding
1-20 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ ever be all zeros. Mode-2 communication always ensures signal inversion, while mode 3 usually does. ZCS is the only line coding allowed over DS1 restricted channels. Restricted channels are those that guarantee successful transmission for voice and for data that has been encoded to ensure that there is never an all-zeros byte.
Page 41: Table 1-6. Signal-Inversion Requirements
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Signal Inversion Signal inversion is the replacement of all 1s in a digital transmission stream with 0s; and the replacement of all 0s with 1s. The use of signal inversion is related to the transmission facilities, the DMI mode, and the line coding.
Page 42: Table 1-7. Data-Module Capabilities
1-22 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Data User Data Module Mode Rate 7400 series to 19.2 kbps DTDM to 19.2 kbps MPDM 64 kbps 56 kbps to 19.2 kbps MPDM/M1* 0 64 kbps 56 kbps to 19.2 kbps 3270 A to 9.6 kbps 64 kbps...
Page 43 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ TABLE 1-7: Data-Module Capabilities (Part 2 of 2) Data User Data Module Mode Rate PC/ISDN to 19.2 kbps Platform with ASCII 64 or 56 kbps Yes terminal emulation Constellation 3 64 kbps NOTE 1: The mode-2 handshake will not work over other than 64-kbps facilities (for example, robbed-bit facilities). Use the MPDM/M1* for mode-1 calls made over robbed-bit facilities.
Page 44: Figure 1-7. D4 Framing
1-24 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ COMBINED F FRAME # FRAME Framing A frame is a set of 24 8-bit time slots grouped as a single transmission unit. Each DS1 frame has 192 bits 8), plus 1 bit, known as the framing bit, that is inserted at the beginning of each frame. Since each frame repeats time slots in the same sequence as previous frames, the time slots representing a single conversation or data stream form a channel.
Page 45 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The framing format does not place any requirement on the type of signaling or line coding to be used. However, the type of framing used at both ends of the DS1 transmission facility must be identical. D4 Framing A synchronization pattern is a continuously repeating string that orients the receiving end to a frame’s boundaries during a transmission.
Page 46: Figure 1-8. The Extended Super Frame
1-26 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ FRAME FRAME BIT NUMBER DEFINITIONS DATA LINK F BIT (DL) CRC-6 F BIT DATA LINK SIGNAL FRAME SYNC PATTERN DATA LINK SIGNAL CRC-6 F BIT DATA LINK SIGNAL FRAME SYNC PATTERN DATA LINK SIGNAL CRC-6 F BIT DATA LINK SIGNAL...
Page 47: Table 1-8. 24Th-Channel Signaling Arrangement — Dmi Bos
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Facilities using RBS carry digital data at 56 kbps. They can be used to carry voice, voice-grade data, or data that uses only 56 kbps of the available 64-kbps bandwidth (for example, mode-1 data). 24th-Channel Signaling 24th-channel signaling permits the channels to use their full 64 kbps bandwidth capacity.
Page 48: Table 1-9. 24Th-Channel Signaling Types Vs Trunk Types And Destinations
1-28 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ number and the signaling state for that channel. The channel identiﬁcation number is necessary since the channel signaling information may not be synchronized with the voice or data channel that it describes. Some types of public network equipment were incompatible with this type of 24th-channel signaling and, as a result, another type of 24th-channel signaling, called DMI-BOS, was developed.
Page 49: Multiplexing Outside The Switch
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ MULTIPLEXING OUTSIDE THE SWITCH As signals propagate away from the switch, they can be multiplexed onto increasingly higher-capacity facilities. As the capacity of facilities increases, the transmission medium can also change — for example, from metallic to ﬁber to microwave and back again.
Page 50: Figure 1-9. T1 Trunk Multiplexing
1-30 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ HOST DIGITAL PRIVATE FACILITIES CHANNEL BANK ANALOG PBX Legend: CDM = channel division multiplexer CEM = channel expansion multiplexer CSU = customer service unit DACS = digital access and cross-connect system directly access the OCU port on the D4 channel bank by ﬁrst passing the signal through a digital service unit (DSU) that is set to communicate at 2.4, 4.8, 9.6, or 56 kbps.
Page 51: Getting The Signal Ready For The Central Ofﬁce
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Compressing the Signal Through a process called adaptive differential pulse-code modulation (ADPCM), voice transmissions can be compressed so that they consume only half of their original bandwidth. This means that 24 T1 channels can be compressed to 12 channels; and the contents of two T1 trunks can be condensed to one (see ﬁgure 1-9).
Page 52: Changing The Transmission Medium From Metallic To Fiber-Optic
1-32 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ AT&T offers two types of CSUs. The ESF T1 CSU, AT&T’s most recent offering, can be set for D4 or ESF framing, and ZCS or B8ZS line coding. Applications for the 550/551 CSU are much more limited since it can be set for only D4 framing and ZCS line coding.
Page 53: Figure 1-10. Possible Multiplexed Connections
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ 3B Computers PC 6300 AT&T FAX 3510D terminals at various rates Teleconferencing T1/DS1 could be twisted pair or ﬁber via the ﬁber-optic interface Figure 1-10. Possible Multiplexed Connections 7000 Series System 75/85 Terminals or G1/G2 PC 6300 PC 6300 DIMENSION PBX...
Page 54: Statistical Multiplexing
1-34 MULTIPLEXED COMMUNICATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Note that the Digital Access and Cross-Connect System (DACS) takes input multiplexed up to the DS1 level. Therefore, communications multiplexed above this level must be demultiplexed before they can be processed by the central ofﬁce. STATISTICAL MULTIPLEXING Statistical multiplexers assign a high-speed (56- or 64-kbps) channel for utilization by several lower-speed (subrate data) devices.
Page 55: Local Exchange Trunks
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Trunks are the transmission medium through which voice and data signals travel from one switch to another. Studying the variety of ways trunks can differ can help simplify your decisions when you implement and administer a network. Trunks can vary according to: Application Connectivity Administration options...
Page 56: Tie Trunks
1-36 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ attendant or ACD agents. 800-service trunks — 1-way incoming trunks connecting the switch to a CO equipped to handle 800 Service calls (also known as INWATS). These trunks allow a customer, for a monthly charge, to receive incoming station-to-station calls from telephones in a deﬁned service area without charge to the caller.
Page 57: Special-Access Trunks
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ numbers (without their accompanying location code) are sent over access trunks to identify a call destination. Bypass access trunks — 1-way outgoing trunks that connect a tandem switch to a main switch that is "homed on"...
Page 58: Connectivity
1-38 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ the switch of origin for routing and processing, and, then, disengages the RLT, readying it for another call. Advanced Private Line Termination (APLT) Trunks APLT trunks handle calls between private switches on customer premises and private switches on central ofﬁce premises.
Page 59: System 85/G2 Administration
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Access can also be switched or nonswitched. With switched access, either the LEC or interexchange carrier provides access to their switching complex for the special services for which you have contracted. With nonswitched access, either the LEC or the interexchange carrier provides you with a direct connection to the special services for which you have contracted.
Page 60 1-40 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ signals on-hook on all calls by opening the path between the tip and the ring. LS (loop start) supervision — A supervisory signaling scheme used between a telephone and a PBX in which the telephone completes the loop current path.
Page 61: System 75/G1 Administration
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ DMI — A DS1 link that uses the digital multiplexed interface (DMI) as the level 2 protocol on the bearer or information channels. AVD — When a trunk is administered as AVD, it can carry only voice and digital data. Without explicitly administering the trunk as AVD, only voice and voice-grade data are allowed.
Page 62: Interface Circuit
1-42 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Framing — On System 85 and G2, you can administer a DS1 port for either D4 or ESF framing through PROC 260 Word 1, ﬁeld 6. On System 75 and G1, use the DS1 Circuit Pack Screen to set these options.
Page 63: Table 1-10. Generic 1 And Generic 2 Analog Trunks — Voice/Voice-Grade Data Bcc
1-43 TRUNKING _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table 1-10. Generic 1 and Generic 2 Analog Trunks — Voice/Voice-Grade Data BCC...
Page 64 1-44 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 65: Table 1-11. Generic 1 And Generic 2 Digital Trunks — Voice Bcc
1-45 TRUNKING _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table 1-11. Generic 1 and Generic 2 Digital Trunks — Voice BCC...
Page 66 1-46 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 67 1-47 TRUNKING _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________...
Page 68: Table 1-12. Generic 1 And Generic 2 Digital Trunks — 64 Kbps User Rate — Modes 0,2,3 Bccs
1-48 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table 1-12. Generic 1 and Generic 2 Digital Trunks — 64 kbps User Rate — Modes 0,2,3 BCCs...
Page 69: Table 1-13. Generic 1 And Generic 2 Digital Trunks — 56 Kbps User Rate — Mode 1 Bcc
1-49 TRUNKING _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table 1-13. Generic 1 and Generic 2 Digital Trunks — 56 kbps User Rate — Mode 1 BCC...
Page 70 1-50 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 71 1-51 TRUNKING _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________...
Page 72 1-52 TRUNKING _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 73 2. COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ A network is an interconnected group of communications systems that can exchange voice and data across the transmission media that connect them. Arranging communications systems into networks involves physically linking the systems (nodes) together with the appropriate hardware.
Page 74: Types Of Networks
COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ TYPES OF NETWORKS The type of network you install depends upon the geographical distribution of the network nodes, the capabilities you need in each node, and the relative cost of each networking alternative. To satisfy these variables, you can install any of the following network types.
Page 75: Network Evolution
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ LOCATION A LOCATION B Electronic tandem network/Software-Deﬁned Network (ETN/SDN) hybrid network — A network in which users served by the public network are integrated into a private ETN. When users are scattered geographically, this may be a viable alternative to additional private network switches in dispersed locations, or public network toll calls from remote locations.
Page 76: Basic Networking Software
COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ The networking software has been packaged to accommodate this type of network evolution. Table 2-1 shows the types of software (and their PECs) that must be activated to enable particular types of networks. Network Type Package Tandem Tie Trunk...
Page 77: Main-Satellite/Tributary Software — The Udp And Multipremises Packages
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ network calls. In addition, ARS provides toll-sensitive routing. (See Network Call Processing later in this chapter for further details.) Trunk access through dial access codes. This is the capability that enables a private tandem tie trunk network and a MS/T network on the Internal dial plan —...
Page 78: Electronic Tandem Network Software — The Pna And Etn (Standard Network) Packages
COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ switch for processing. , System 85, and Generic 2 Multipremises Package DIMENSION The set of software capabilities that enable a to function as a node in a MS/T network are provided through the Multipremises package. The Multipremises package uses extension number steering to route a call through the network.
Page 79: Distributed Communications System
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The Uniform Dial Plan function — With this function, the switch uses the extension number to ﬁnd the RNX. The RNX is used to route the call through AAR to its destination. The implementation of the Uniform Dial Plan function here is identical to that used for the System 75 and Generic 1 communications systems when the UDP or PNA package is activated.
Page 80: Internal Dial Plan
COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ On all switches, the internal dial plan comes with the basic software. On the Generic 2 communications system, ARS is provided with the basic software; on the System 75 and Generic 1 communications system, ARS is a separate offering.
Page 81: Figure 2-1. Internal Dial Plan Interactions
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ (NPA) NNX XXXX NETWORK NETWORK NETWORK NETWORK Figure 2-1. Internal Dial Plan Interactions — Local station number dialing— When only an extension number is dialed, the internal dial plan ﬁrst attempts to match the extension number with a terminal on the same switch. If no match is made and if MS/T or ETN networking software is active, the internal dial plan submits the call to the networking software for further analysis.
Page 82: Auxiliary Call Information
2-10 COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ the extension and RNX number to AAR for processing. The UDP function is available on the System 75 and Generic 1 communications systems when either the UDP or PNA package is activated. On the communications systems, it becomes available only when the ETN (Standard Network) package is active.
Page 83: Automatic Alternate Routing
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Bearer capabilities — Bearer capability (System 75 R1V3 and Generic 1 communication systems) and bearer capability classes of service (System 85 R2V4 and Generic 2 communications system) are assigned to indicate whether calls are analog or digital. Within the scheme of bearer capabilities, digital calls are further classiﬁed by the DMI mode in which they are transmitted.
Page 84: Figure 2-2. Aar Processing
2-12 COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ EXTENSION EXT + NODE NUMBER PORTABILITY FROM INTERNAL DIAL PLAN UNIFORM EXT + RNX DIAL PLAN FUNCTION number. If the Uniform Dial Plan function is effective in the switch, AAR receives the RNX number of the destination switch and the destination extension number.
Page 85 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Selecting a Trunk Group Various criteria make one trunk group more appropriate than another for routing a call. Among these criteria are cost, speed, transmission medium, and the bearer capability class of the call (which lets the system match like digital formats).
Page 86: Automatic Route Selection
2-14 COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Automatic Route Selection Automatic Route Selection (ARS) is the feature that handles outgoing public network calls that callers have dialed using the ARS feature access code (usually a 9). ARS comes with basic Generic 2 communications system software;...
Page 87: Figure 2-3. Ars Processing
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ FROM 9 + (NPA) + (NNX) + EXT INTERNAL DIAL PLAN YES (S75/G1) PARTITION GROUP NUMBER (S75/G2) FOREIGN 6-DIGIT TABLE TABLE TENANT PARTITION (S85/G1) Unauthorized calls. These ARS sends to intercept. International exceptions. These ARS sends directly to pattern selection. This capability is especially helpful in routing international calls that require special handling.
Page 88 2-16 COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ 0 in position 1 — ARS knows that these are IXC (Generic 1 only) or telephone company operator- assisted calls and sends them on to pattern selection. During pattern selection, a pattern that forwards the calls to the central ofﬁce or IXC operator will be chosen.
Page 89: Networking Feature Parameters
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ When an IXC facility is chosen and the caller dialed an AT&T number. In this case, ARS can be used to insert an IXC preﬁx. When an AT&T facility is chosen and the caller dialed an IXC number. In this case, ARS can be used to delete the IXC preﬁx.
Page 90: Table 2-2. Network Administration Terminals And Systems
2-18 COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table 2-2. Network Administration Terminals and Systems Switch Version DIMENSION System 85 R2V1 System 85 R2V2 and R2V3 System 85 R2V4 Generic 2 System 75 R1V1 to R1V3 Generic 1 * The full names of the terminals and systems are: SMT=System Management Terminal;...
Page 91: Table 2-3. Networking Feature Parameters
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table 2-3. Networking Feature Parameters DIMENSION FEATURE Iss 1 Iss 3 ACA: # Char in Display AAR: # of Patterns # of Trk Grps/ Pattern ARS: # of Patterns # of Trk Grps/ Pattern # of 6-Digit Translations # of Patterns/...
Page 92 2-20 COMMUNICATION SYSTEM NETWORKING — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 93: Interactions With Other Networks
3. TANDEM TIE TRUNK NETWORKS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ A tandem tie trunk (TTT) network is an network of , System 85, and/or Generic 2 switches DIMENSION linked by dial-repeating trunks. In this type of network, calls are not automatically routed to the ﬁnal destination.
Page 94 TANDEM TIE TRUNK NETWORKS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 95: Figure 4-1. Standalone Ms/T Network
4. MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Main-satellite/tributary (MS/T) networks are arrangements of switches in which one switch is designated as the main, while subtending switches are satellites or tributaries. The main switch is fully functional; each satellite uses the trunks and attendants at the main switch.
Page 96: Main-Satellite Conﬁguration
MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ MS/T CONFIGURATIONS There are two types of MS/T conﬁgurations: main-satellite and main-tributary. Main-Satellite Conﬁguration For a main-satellite conﬁguration (see ﬁgure 4-1), attendant positions and public network trunks are typically concentrated at the main switch.
Page 97: Main-Tributary Conﬁguration
MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ TRIBUTARY CENTRAL EXTENSIONS OFFICE (727-XXXX) 3600-3699 LDN/DID (725-XXXX) CENTRAL OFFICE SATELLITE PBX (A) EXTENSIONS 3300-3399 3500-3599 Figure 4-2. MS/T Coordinated Numbering Main-Tributary Conﬁguration A main-tributary conﬁguration is one in which the subtending location is the tributary. This conﬁguration is very similar to a main-satellite conﬁguration with the following exceptions: 1.
Page 98: Ms/T Features
MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ MS/T FEATURES MS/T conﬁgurations are implemented differently on different communications systems: The System 75 and Generic 1 communications systems use the Uniform Dial Plan (UDP) package to function as nodes in MS/T networks.
Page 99: Figure 4-3. Dialing Patterns From Tributary Or Satellite To Main
MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ S/T: DIMENSION, SYSTEM 85, GENERIC 2 S/T NETWORKING PACKAGE: MULTIPREMISES WITH ETA MAIN DIAL: EXTENSION Figure 4-3. Dialing Patterns From Tributary or Satellite to Main MAIN: DIMENSION, SYSTEM 85, GENERIC 2 MAIN NETWORKING PACKAGE:...
Page 100: Figure 4-6. Dialing Patterns From Satellite Or Tributary To Tandem
MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ MAIN: DIMENSION, SYSTEM 85, GENERIC 2 MAIN NETWORKING PACKAGE: MULTIPREMISES TANDEM MAIN DIAL: 1) DAC TO TANDEM 2) RNX-XXXX Figure 4-5. Dialing Patterns From Main to Tandem S/T: DIMENSION, SYSTEM 85, GENERIC 2 S/T NETWORKING PACKAGE:...
Page 101: Routing Incoming Calls
MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Routing Incoming Calls Except for a conﬁguration that incorporates a bypass access trunk between an ETN node and a tributary, all calls into the MS/T complex come through the main. Calls arrive at the main from both the public and private network.
Page 102: Engineering Considerations
MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ From the main to the satellite or tributary: The caller dials the destination extension and the AAR databases route the call appropriately. This capability is available with the UDP, PNA, and ETN (Standard Network) packages. (See ﬁgures 4-4(E) and (F).) The caller dials the DAC plus the extension number and the system ﬁnds the trunk associated with the DAC and passes the extension number to the next switch over the trunk group that the DAC designates.
Page 103: Interactions
MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Senderized operation. Can automatically delete digit(s) at the sending end and add digit(s) at the receiving end. Can be either touch-tone or rotary operation. Can do extended trunk access from satellite/tributary to main only (not provided in System 75 or Generic 1).
Page 104 4-10 MAIN-SATELLITE/TRIBUTARY (MS/T) NETWORKS THROUGH THE UDP OR MULTIPREMISES PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Distributed communication system (DCS) software can coexist with MS/T software. Therefore, it is possible for MS/T network switches to be nodes in a DCS cluster.
Page 105: Etn Configurations
5. ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ An ETN is a wide-area private network that tandems calls through one or more switches to reach their destinations. In an ETN, the tandem switches are tied together with tie trunks and other equipment needed to transmit voice and data.
Page 106: Etn Trunks
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ The characteristics of a hierarchical network (see ﬁgure 5-1) are: Each tandem switch has an assigned level (upper and lower). Each lower level switch connects to an upper level switch. Upper level switches are interconnected.
Page 107: Figure 5-1. Typical 2-Level Hierarchical Electronic Tandem Network (Etn Conﬁguration
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ MAIN DIMENSION TANDEM SWITCH FINAL BYPASS ACCESS TIE TRUNK OVERFLOW SYSTEM 85 TANDEM SWITCH ACCESS MAIN TRUNKS SATELLITE TRIBUTARY TRUNKS Figure 5-1. Typical 2-Level Hierarchical Electronic Tandem Network (ETN) Conﬁguration MAIN UPPER LEVEL FINAL...
Page 108: Access And Bypass Access Tie Trunks
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Access and Bypass Access Tie Trunks An access tie trunk is a 1-way outgoing or 2-way trunk connecting a main to a tandem switch. A bypass access tie trunk is a 1-way outgoing trunk connecting a tandem switch to a main, satellite, or tributary that is homed on another tandem switch.
Page 109: Uniform Numbering Plan
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Off-Net Trunks The public network trunks carry off-net AAR call trafﬁc when the call is identiﬁed by a 10-digit number (NPA-NXX-XXXX). In some cases, calls may be carried as far as possible on-net and then routed to off- net trunks.
Page 110: Figure 5-3. Private Network Uniform Numbering Plan
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ 555-1234 TANDEM 444-1234 (444) TO C.0. ATTENDANT 444-0111 TO C.0. ATTENDANT 689-0111 TO C.0. ATTENDANT 654-0111 Figure 5-3. Private Network Uniform Numbering Plan TO C.0. TANDEM (555) MAIN...
Page 111: Automatic Route Selection
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Note that a System 75 or Generic 1 communications system that functions as a tandem supports only a 7- digit uniform numbering plan; while support a 5-, 6-, or 7-digit uniform numbering plan.
Page 112: Extension Number Portability Clusters
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ In some cases, the software and/or administration used to implement the above types of networks reside on the same switch as do the ETN (Standard Network) package or the Private Network Access package. This is true of extension number portability, release link trunk networks, and distributed communications system software and/or administration.
Page 113: Software-Deﬁned Network
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Like System 85 and Generic 2 communications systems that function as ETN tandems, ENP nodes require the ETN (Standard Network) package. At every ENP node, all extensions are identiﬁed by the number of the node where they reside and the trunk connection to that node.
Page 114: Figure 5-5. Feasible Etn/Sdn Conﬁguration
5-10 ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ 7- OR 10- DIGIT S85/ 0- TO 7- DIGIT S85/ S75/ 7-DIGIT DIRECT ACCESS LEGEND: ACP - SDN ACTION POINT. DID - DIRECT INWARD DIALING. DIM FP8 - AT&T DIMENSION 2000 WITH FEATURE PACKAGE 8.
Page 115: Figure 5-6. Call Flow Sdn - To - Etn
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ 3456 4. The ACP updates any pertinent billing records. 5. Based upon the information it received from the NCP, the ACP routes the call to the egress ACP (a 4ESS).
Page 116: Release Link Trunk Networks — Cas And Acd
5-12 ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ 346-1234 346-1234 8-346-1234 7. The egress ACP routes the call to the destination switch, which rings the terminal indicated by the extension number it receives. Release Link Trunk Networks —...
Page 117: Figure 5-8. Centralized Attendant Service
ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ TANDEM BRANCH TIE LINE LINE TIE LINE BRANCH TANDEM Figure 5-8. Centralized Attendant Service Centralized Attendant Service Centralized Attendant Service (CAS) is a feature that offers companies the ability to centralize their attendants at a CAS main switch.
Page 118: Distributed Communications System Clusters
5-14 ELECTRONIC TANDEM NETWORK (ETN) THROUGH THE ETN AND PNA PACKAGES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Distributed Communications System Clusters The distributed communications system (DCS) is a information system that provides a messaging overlay for main-satellite/tributary (MS/T) networks, electronic tandem networks (ETNs), or ETN-MS/T complexes that are designed for DCS implementations.
Page 119: Figure 6-1. Distributed Communications System (Dcs) Cluster
6. DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The distributed communications system (DCS) is a information system that provides a messaging overlay for main-satellite/tributary (MS/T) networks, electronic tandem networks (ETNs), or ETN-MS/T complexes that are designed for DCS implementations. This overlay provides communication among the network nodes so that the operation of a limited number of features is transparent across the network.
Page 120: Dcs Clusters
DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DCS CLUSTERS DCS is installed on groups of switches, called "DCS clusters." Nodes in DCS clusters can be System 75, System 85, Generic 1, or Generic 2 communications system. Each node must share the cluster’s uniform numbering plan.
Page 121: Tie Trunks
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Tie Trunks In ETNs, the tie trunks connecting DCS nodes are intermachine tie trunks. On the System 75 and Generic 1 communications system, they are administered as tandem trunks; while on the Generic 2 communications system, they are type 41 trunks. In MS/T networks, on the System 75 and Generic 1 communications system, the tie trunks are administered as tie;...
Page 122: Figure 6-2. Internally Connected Dcs Signaling Channel Over A Ds1
DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ administrable amount of time elapses, the packet is retransmitted. The link can be reset and restarted if packets are not delivered or if the packets arrive out of sequence. Transmission Media Both analog and digital facilities can carry DCS signals between network nodes (see the DCS Signaling Link Connections section later in this chapter).
Page 123: Figure 6-3. Direct Link Dcs Connections
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ (See chapter 9 for detailed permanent connection conﬁgurations. The System 75 and Generic 1.1 Implementation manual (555-204-654) and the System System 85 and Generic 2 Feature Descriptions manual (555-104-301) provide permanent connection implementation details.) When DCS signaling is channeled through a DS1 port, the signaling channel can be carried over the same DS1 facility as that which carries voice between the network nodes.
Page 124: Figure 6-4. Minimized Link Connections
DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Linkage Design Signaling links between DCS nodes can be designed with an underlying direct linkage or minimized linkage philosophy. Direct Linkage. When a DCS cluster is designed using direct linkage, every DCS node is directly connected to every other DCS node.
Page 125: Figure 6-5. Dciu/Pi Linkage In A Dcs Cluster
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Figure 6-5. DCIU/PI Linkage in a DCS Cluster Mixed Link Connections. In reality, most DCS clusters exhibit both direct and minimized linkage. Figure 6-5 shows the signaling links for a 12-switch DCS conﬁguration. This cluster uses some nondirect signaling links.
Page 126: System 75 Or Generic 1 (G1) To System 75 Or G1
DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DCS SIGNALING LINK CONNECTIONS Many variables inﬂuence how the signaling channel on one DCS node is connected to the signaling channel on another DCS node. Chief among these variables is the types of communications systems being connected.
Page 127: Figure 6-9. Long Haul Digital Signaling: System 75/G1 To System 75/G1 Via Isdn Pri
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ TN764 (DIGITAL LINE) MTDM TN760 (TIE TRUNK) TN722 OR TN767 (DS1) SYSTEM 75/G1 Figure 6-7. Long Haul Analog Signaling: System 75/G1 to System 75/G1 Via Modem TN722 OR TN767 (DS1) SYSTEM 75/G1 Figure 6-8. Long Haul Digital Signaling: System 75/G1 to System 75/G1 Via AVD DS1 TN767 (PRI) SYSTEM 75/G1...
Page 128: Figure 6-10. Short Haul Digital Signaling: System 75/G1 To System 75/G1 — Direct Via Mpdm Or Mtdm
6-10 DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ TN764 (DIGITAL LINE) TN760 (TIE TRUNK) TN722 OR TN767 (DS1) SYSTEM 75/G1 Figure 6-10. Short Haul Digital Signaling: System 75/G1 to System 75/G1 — Direct Via MPDM or MTDM System 85 or Generic 2 (G2) to System 85 or G2 RS449 DCIU...
Page 129: Figure 6-13. Long Haul Digital Signaling: System 85/G2 To System 85/G2 Via Isdn Pri
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RS449 DCIU DCIU TN760 SN232 (TIE TRUNK) (TIE TRUNK) TN722 ANN11 OR TN767 (DS1) (DS1) GENERIC 2 SYSTEM 85/G2 WITH WITH UNIVERSAL TRADITIONAL MODULE MODULE Figure 6-12. Long Haul Analog Signaling: System 85/G2 to System 85/G2 Via Modem SIGNALING CHANNEL DCIU DCIU...
Page 130: Figure 6-16. Long Haul Analog Signaling: System 75/G1 To System 85/G2 — Direct Via Modem
6-12 DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ System 75 or Generic 1 (G1) to System 85 or Generic 2 (G2) TN754 MTDM (DIGITAL LINE) TN760 (TIE TRUNK) TN722 OR TN767 (DS1) ANALOG OR DS1 VOICE CHANNEL SYSTEM 75/G1 Figure 6-15.
Page 131: Figure 6-18. Long Haul Digital Signaling: System 75/G1 To System 85/G2 Via Isdn Pri
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ USING AVD DS1* CARRIER TN722 OR TN767 (DS1) SYSTEM 75/G1 *ONE OF THE 23 AVD CHANNELS IS USED FOR DCS SIGNALING: THE REMAINING 22 CHANNELS CAN BE USED FOR VOICE PURPOSES. Figure 6-17. Long Haul Digital Signaling: System 75/G1 to System 85/G2 Via AVD DS1 TN767 (PRI) SYSTEM 75 (R1V3)/G1...
Page 132: Figure 6-19. Short Haul Digital Signaling: System 75/G1 To System 85/G2 — Direct Via Mpdm
6-14 DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ TN754 (DIGITAL LINE) TN760 (TIE TRUNK) TN722 OR TN767 (DS1) ANALOG OR DS1 VOICE CHANNEL SYSTEM 75/G1 Figure 6-19. Short Haul Digital Signaling: System 75/G1 to System 85/G2 — Direct Via MPDM Signaling Links DIMENSION signaling links are set up identically to System 85 and Generic 2 long haul and short haul...
Page 133: Table 6-3. Availability Of Attendant Features
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table 6-3. Availability of Attendant Features DIMENSION FEATURE Iss 3 Alpha Display Call Waiting Busy Verif of Lines Calling Number Display Class-of-Service or Restriction Display Control of Trunk Group Access Direct Trunk Group Selection Trunk Group Busy Warning Indicator...
Page 134 6-16 DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Group Selection button. Busy Veriﬁcation of Terminal Lines The attendant can verify a terminal’s state (busy or idle) at any DCS node/endpoint. Calling Number Display The alphanumeric display shows the caller’s extension number. The DCS console can display 5-digit as well as 4-digit extension numbers.
Page 135: Transparent Voice Terminal Features
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Transparent Voice Terminal Features The following voice terminal features operate transparently at voice terminals attached to nodes within a DCS cluster. (See table 6-4 for a list of transparent voice terminal features and the communications systems from which you can expect transparency.) Table 6-4.
Page 136 6-18 DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ If the called party is at a System 85, Generic 2, or activated if the called node is returning busy tone or special audible ringback. If the called party is at a System 75 or Generic 1 endpoint, the callback call can be activated if the endpoint is returning busy tone, special audible ringback, or audible ringing.
Page 137: Audio Information Exchange (Audix) Features Transparency
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ feature allows the caller to leave a ‘‘call me’’ message for the called party. The switch automatically creates a message that contains: calling party name and extension number, date, time, and a short customer-speciﬁed message such as ‘‘please call’’. Switch-based LWC is not transparent from or to intermediate switch.
Page 138: Figure 6-20. Audix In A Dcs Network
6-20 DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ AUDIX VOICE LINKS SWITCH COMMUNICATIONS PROCESSOR Figure 6-20. AUDIX in a DCS Network Call answering through Call Forwarding — A user on a remote switch may redirect all calls to the AUDIX ACD group on the host switch.
Page 139: Engineering Considerations
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Leave Word Calling — Leave Word Calling messages can be stored on AUDIX for users on remote switches. Leave Word Calling activation can be from any switch. ENGINEERING CONSIDERATIONS The design of a DCS cluster is the process of determining the size, quantity, and conﬁguration of the switching nodes, internode (intracluster trunks), main PBX access lines, data links, and off-net facilities.
Page 140 6-22 DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DCIU or PI Link i, channel j Since some delay is introduced if the message takes a detour like this, however, the number of hops is not unlimited. If too many hops are used to get the message to the destination, the last digit of the call will arrive at the system at the other end of the trunk group and the call will be sent either to a station or on to another node without the message data to make the call transparent.
Page 141: Administration Considerations
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ ADMINISTRATION CONSIDERATIONS To determine how to administer DCS nodes, refer to the Generic 1.1 Implementation manual (555-204-654), the Generic 2 Feature Descriptions manual (555-104-301), and System 75 and System 75 XE Application Notes — Distributed Communications System, Issue 3, (555-209-003). In addition, when you administer a communications system that is a node in a DCS cluster, consider the following information: Trunk groups and trunk group members in a DCS conﬁguration must be numbered and administered...
Page 142 6-24 DISTRIBUTED COMMUNICATIONS SYSTEM (DCS) _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ If the far-end switch from a System 75 or Generic 1 is a System 85, Generic 2, or if a 5-digit dialing plan is used with AAR that routes the ﬁrst two digits to an RNX, intermachine tie trunks must be administered at the System 75 or Generic 1.
Page 143 7. DATA CONNECTIVITY — AN OVERVIEW _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ This part of the AT&T Network and Data Connectivity document explains how to use your communications system to connect one data communications device or network to another device or network. This chapter, in particular, deﬁnes some basic data communications principles, and it explains the data features that your communications system offers.
Page 144: Data Communications Variables
DATA CONNECTIVITY — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DATA COMMUNICATIONS VARIABLES Data terminal equipment (DTE) are devices where data originates and/or terminates. Host computer ports and terminal ports usually function as DTEs. Your communications system can be used to switch data originating or terminating at any of the following DTEs and networks (see ﬁgure 7-1): Terminals Personal computers (PCs)
Page 145: Figure 7-1. Possible Data Connections
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ NETWORKING DIGITAL PBX PACKET SWITCH SYNCHRONOUS DIGITAL PBX CLUSTER CONTROLLER 3270 DATA MODULE ASYNCHRONOUS AT&T 6500 MULTI- FUNCTION COMMUNI- CATIONS SYSTEM MAINFRAME COMPUTER DATA CONNECTIVITY — AN OVERVIEW PUBLIC- SWITCHED ISN OR NETWORK STARLAN POOLED MODEM HOST...
Page 146: Synchronous Vs. Asynchronous
DATA CONNECTIVITY — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ communications path. Interface protocols that control communication between links in a data network, but do not cross the network. These protocols include the part of the RS-232 protocol that controls communication between the originating DTE and DCE.
Page 147: Simplex Vs. Half-Duplex Vs. Full-Duplex
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ ONE CHARACTER (7 OR 8 BITS) AT A TIME Figure 7-2. Synchronous vs. Asynchronous Communication Protocol converters and terminal emulators can convert communications between synchronous and asynchronous. See chapter 8 for an explanation of how these devices and programs are used to connect dissimilar devices.
Page 148: Transmission Speed
DATA CONNECTIVITY — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ SIMPLEX HALF DUPLEX (TURNAROUND) FULL DUPLEX Parallel vs. Serial The terms parallel and serial describe how bits are sent over the transmission media (see ﬁgure 7-4). With parallel transmission, all the bits composing the byte are transmitted at the same time, each bit being sent over a different subchannel.
Page 149: Type Of Communications Channel
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Type of Communications Channel Channels can be classiﬁed according to the the type of switch that creates them, the method used to assign them, the type of information they pass, and the transmission mode. Creating Switch —...
Page 150 DATA CONNECTIVITY — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Channel Assignment — Dial-up vs. Dedicated Connections The assignment of a communications stream to a path or channel through a circuit switch is made dynamically or on a permanent basis. The dynamic assignment of a communications stream to a channel is provided when the user dials the telephone number of the destination.
Page 151: Special Data Features
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ At the point in the communications stream where the transmission mode changes between analog and digital the switch automatically inserts a modem pool member. (See the Transmission States section of chapter 1 for further details on the points in the transmissions stream where transitions from analog to digital may occur.) A modem pool member is an arrangement of data modules and modems that takes analog signals and transforms them to DCP and vice versa.
Page 152: Data Call Setup From A Voice Terminal
7-10 DATA CONNECTIVITY — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table 7-1. Data Feature vs Communications Systems Data Services Features Data Call Setup From a Voice Set 1-Button Transfer with Preindication Manual Transfer Terminal Dialing Numeric Dialing Default Dialing Mnemonic Dialing Computer Dialing Data Hot Line...
Page 153: Data Only Off-Premises Extension
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Note that BRI terminals follow the asynchronous user interface speciﬁcation, which means that the terminals are always in the command mode by default. This implies that whenever a call is to be placed, the user must always dial "d CR " at the very least. Since the concept of hot lines means that all a user need do is go off-hook to place a call, there is really no such thing as a true hot line for BRI terminals.
Page 154: Figure 7-5. Off-Premises Data-Only Extension — Conﬁgurations
7-12 DATA CONNECTIVITY — AN OVERVIEW _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ RS-232C MTDM RS-232C MTDM RS-232C SYSTEM 85, MTDM SYSTEM 75, GENERIC 1/2 MODEM MTDM MTDM MTDM NOTE: SYNCHRONOUS-TO-ASYNCHRONOUS ADAPTERS MAY BE ADDED AS REQUIRED. Figure 7-5. Off-Premises Data-Only Extension — Conﬁgurations "UP TO 21 SYNCHRONOUS CHANNELS"...
Page 155: Data Communications Capabilities
8. DATA COMMUNICATIONS CAPABILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Your communications system can be used to connect a single endpoint with the the following devices and networks for data communications: Data terminal equipment (DTEs), such as PCs, CRTs, printers, computer ports — through data communications equipment (DCEs) Local area networks (LANs) —...
Page 156 DATA COMMUNICATIONS CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 157: Protocol Converters
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Through your communications system, you can communicate with both asynchronous and synchronous DTEs. The DTEs may include terminals and personal computers, as well as host computer ports. Designing these connections is a multi-step process: First, you must determine whether the DTEs are compatible.
Page 158: Terminal Emulators
DTE CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Terminal Emulators Many host and personal computer manufacturers endorse terminal emulation software that will send data in a format that the destination DTE expects. For example, DEC’s VT100 AT&T’s ATT513 and ATT4410 packages give IBM-compatible PCs the ability to communicate in the same formats as the terminals for which the packages are named.
Page 159: Dce Possibilities
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ DCE POSSIBILITIES DCEs that communicate with AT&T communications systems can be categoried as follows: Data Modules — Link DTEs with the switch’s digital ports — that is, BRI and DCP ports. Because data modules are digital, they cannot be used with standalone remote DTEs that communicate through the public network unless DSUs and the the connection.
Page 160: Data Module Characteristics
DTE CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Standalone Data Modules Standalone data modules are self-contained pieces of equipment that transform the transmission signal as it enters and exits the switch. Standalone data modules include the following: Modular Processor Data Module (MPDM) — A DCP data module that is used for both synchronous and asynchronous applications.
Page 161 DTE CONNECTIONS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ If you choose to use DCP (digital-line or GPP) ports for the connection, refer to table 8-1 to determine which DCE best meets your needs. Table 8-2 lists your choices if you select a BRI port for the connection.
Page 162: Table 8-1. Dcp-Port Data Modules
DTE CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Data Voice External Module Terminal Interface Adjunct Data 7404 RS-232C module DTDM 7403 RS-232C 7405 703A 7406 RS-232C data stand 701A 7407 RS-232C data stand MTDM None RS-232C MPDM** None RS-232 RS-449 V.35* 7400A None...
Page 163: Table 8-2. Bri-Port Data Modules
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ TABLE 8-1. DCP-Port Data Modules (part 2 of 2) Data Voice Module Terminal Adjunct PC/PBX 7400 PC/PBX w/3270 emul 7400 3270C None Data Voice Module Terminal Adjunct 7500B* None RS-232D V.35 7505 RS-232D 7506 7507 PC/ISDN None...
Page 164: Modem Pooling Connections
8-10 DTE CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ MODEM POOLING CONNECTIONS Modem pooling connections are used under the following conditions: When an off-premises connection is made over analog facilities, while on-premises facilities are digital. When an off-premises connection is over a DS1 facility that is administered as a "voice." (See ﬁgure 8-5 for this type of modem pooling arrangement.) When the originating and destination DTEs are using different transmission modes (that is, one DTE is using analog transmission, while the other is using digital transmission), regardless of whether they are...
Page 165: Figure 8-3. External Modem Pool Using Intelligent Modems (Hayes-Compatible)
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ TN754 SN270 TN742 SN243 Figure 8-3. External Modem Pool Using Intelligent Modems (Hayes-compatible) 7400B, ADU, ETC TIP-RING (HAYES AT COMPATIBLE) SYSTEM 75, GENERIC 1 DIGITAL PORTION MODEM POOLED MODEM CARD Figure 8-4. Integrated Modem Pool 8-11 DTE CONNECTIONS 7400A...
Page 166: Figure 8-5. Modem Pooling Over A Ds1 Channel
8-12 DTE CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ S75/S85 DATA G1/G2 MODULE 7400A MODEM D = DCP Port; A = Analog Port Figure 8-5. Modem Pooling over a DS1 Channel PRIVATE DATA 24th 24th NETWORK CHANNEL CHANNEL MODEM S75/S85 DATA G1/G2 D MODULE...
Page 167: Local Area Network Connections
LOCAL AREA NETWORK CONNECTIONS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ A local area network (LAN) is a collection of geographically close PCs, printers, and hosts that communicate with each other over a high-speed link. For each PC, the LAN provides high-speed access to shared hardware (like, printers and disks) and software (like, spreadsheets and communications-handling routines).
Page 168: Advantages Of A Communications System In A Lan Environment
8-14 LOCAL AREA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ LAN TRANSMISSION MEDIA The transmission media through which LAN nodes are linked may be ﬁber optic cable, coaxial cable, twisted-pair, or a combination of these. Each transmission medium has a maximum data rate, and distance and capacity limits that characterize it: Table 8-3.
Page 169: Communication Between The Lan And Outside Dtes
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ — It can give outside users access to the LAN and the hardware and software resources that reside there. — It can provide LAN users with access to the lines and trunks attached to communications system. Second, it can let LAN nodes communicate with nodes in other networks.
Page 170 8-16 LOCAL AREA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Type of StarLAN, Token Ring, or Ethernet ISN is not listed in the above table because, unlike the StarLAN, token ring, and Ethernet LANs, ISN provides remote terminal access through its concentrator, rather than a gateway PC. Communication with LANs That Use the StarGROUP Operating System AT&T offers two packages that provide access to and from LANs that use the StarGROUP operating system: the LAN Manager Remote Gateway and the Asynchronous Gateway Server.
Page 171: Figure 8-8. Asynchronous Communications From Lans Operating With Stargroup Software
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ REMOTE PC (RPC) CLIENT 7400B REMOTE PC (RPC) CLIENT (OFF PREMISES) MODEM Figure 8-7. Outside PC Access to a LAN Operating with StarGROUP Software ASYNCHRONOUS WITH StarGROUP CLIENT WORKSTATION Figure 8-8. Asynchronous Communications from LANs Operating with StarGROUP Software running communications software similar to those shown in table 8-4.
Page 172: Communication Between The Lan And Other Networks
8-18 LOCAL AREA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ ISN Communication The AT&T Information System Network (ISN) is a packet-switched LAN that links its nodes together through a data-only digital switch. Communications between ISN nodes and other DTEs is through an ISN concentrator and the communications system.
Page 173: Figure 8-10. Lan-To-Lan Connections Through The Switch
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ BRIDGE MPDM ROUTER Figure 8-10. LAN-to-LAN Connections Through the Switch Table 8-5. LAN-to-LAN Communications Packages Type of StarLAN, Token Ring, or Ethernet StarLAN or Token Ring Token Ring Ethernet a Network Access Unit (NAU) interface; on the communications system side, is the X.25 circuit card, an MPDM, and a DCP port.
Page 174: The Communication System As A Lan Backup
8-20 LOCAL AREA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ 3B2 OR 6386 X.25 MPDM WITH ROUTER StarGROUP X.25 CARD Figure 8-11. X.25/StarGROUP Connectivity X.25 ROUTER WITH StarGROUP 3270 EMULATION PROGRAM FOR END USER ACCESS The Communication System as a LAN Backup In work environments that are totally dependent upon real-time computer interaction, it is very important that access to the LAN server be highly reliable.
Page 175: Public And Private Data Network Connections
PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ This section describes how to use public and private digital data networks to link DTEs and local area networks spread across a wide geographical area. These data networks ensure end to end digital transmission and can be packet-switched or circuit-switched.
Page 176: Circuit-Switched Public Data Networks
8-22 PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ ports, although Memotec also has higher capacity units. (See ﬁgure 8-13.) 7400A, SYSTEM 7400B, ADU, OR ASYNC MPDM ENDPOINTS REDI-ACCESS — For relatively low-volumes of data and intermittent APS access, a less expensive alternative might be dial-up access to shared facilities.
Page 177: Figure 8-14. Public Switched Data Network With Robbed Bit Facilities (Mode 1)
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Image viewing and transfer — Using slow-scan and freeze-frame capabilities, SDS and SDDN let senders and receivers jointly study databases, engineering drawings, and X-rays. Connections to the Public SDN/SDDN Circuit-Switched Data Network Requirements for connections from a PBX DS1 port to a public network destination through SDS or SDDN vary according to the type of signaling used (that is, robbed-bit or ISDN-PRI MOS), and the data speed.
Page 178: Table 8-6. Requirements For Connections From The Pbx To Sds/Sddn
8-24 PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table 8-6. Requirements for Connections from the PBX to SDS/SDDN COMM TYPE FACILITIES CALL SETUP Robbed Bit Dial-up Data Data through a DS1 (see ﬁgure 8-14) Domestic Dial-up N/A Data or Network w/ISDN/PRI...
Page 179: Figure 8-16. International Public Switched Data Network With Isdn-Pri Facilities (Modes 0 1)
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ MPDM, 7400A&B, G1/G2 7500B Figure 8-15. Domestic Public Switched Data Network with ISDN-PRI Facilities (Modes 0, 1, 2, 3) 7500B Figure 8-16. International Public Switched Data Network with ISDN-PRI Facilities (Modes 0, 1) PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS 4ESS PUBLIC SWITCHED...
Page 180: Terrestrial Private Data Network Links
8-26 PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ PRIVATE DATA NETWORKS AT&T leases facilities to private companies for nonswitched connections to private network endpoints. Applications for these connections include high-volume data transmission, bulk voice and data transmission to multiple locations, interactive computer-aided design, and so forth.
Page 181: Table 8-7. Requirements For Pbx-To-Pbx Private Network T1.5 And T45 Connections
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table 8-7. Requirements for PBX-to-PBX Private Network T1.5 and T45 Connections COMM TYPE FACILITIES CALL SETUP Robbed Bit Dedicated or Data (see ﬁgure Dial-up 8-17) Robbed Bit Dedicated Data through D4/DSU (see ﬁgure 8-18) 24th Channel Dedicated or Data or Data or V3=N/A (see ﬁgure Dial-up...
Page 182 8-28 PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ 5. Also, supports 64-kbps 3270C/PC-PBX connections. 6. Older data modules (such as the DTDM, 7404 data module, and 7406 and 7407 data stands), can be used for Mode 2 connections. 7.
Page 183: Table 8-8. Requirements For Pbx-To-Pbx Private Network Spectrum Connections
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Private Terrestrial Connections Through The requirements for using ASDS for PBX-to-PBX connections are given in table 8-8. Table 8-8. Requirements for PBX-to-PBX Private Network Spectrum Connections COMM TYPE FACILITIES CALL SETUP Robbed Bit Dedicated or Data Data through Dial-up Fractional T1...
Page 184: Satellite Private Data Network Links
8-30 PUBLIC AND PRIVATE DATA NETWORK CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ S75/S85 MPDM/M1* G1/G2 AT&T PUBLIC NETWORK Figure 8-21. Private Data Network with Robbed Bit, Fractional T1 Facilities (Mode 1) Satellite Private Data Network Links For satellite private data network links, AT&T offers the SKYNET Digital Service. This service allows AT&T to provide business users with a cost-effective, private network through wide area coverage satellites.
Page 185: The Integrated Telemarketing Gateway
TELEMARKETING HOST CONNECTIONS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ A telemarketing host is a processor that is used for the online input of telephone transactions. To complete the online transaction screens that the host displays, a three-way interaction between the host, the agent, and the communications system takes place.
Page 186: Figure 8-22. Telemarketing Gateway Conﬁguration
8-32 TELEMARKETING HOST CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ AT&T NETWORK 3B2 GATEWAY AT&T 3B2 COMPUTER AT&T SYSTEM 85 DEFINTY GENERIC 1 OR GENERIC 2 SOFTWARE APPLICATION ON HOST COMPUTER AGENT POSITIONS Figure 8-22. Telemarketing Gateway Conﬁguration...
Page 187 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ For further details, see: Integrated Telemarketing Gateway, System Description and Planning (585-246-202) AT&T ISDN Gateway, Planning and Application Development (585-245-201) TELEMARKETING HOST CONNECTIONS 8-33...
Page 188 8-34 TELEMARKETING HOST CONNECTIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 189: Data Network Administration
DATA NETWORK ADMINISTRATION _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The lines and trunks you use for data communication can be administered through the terminals and systems shown in table 2-4. In addition, you can use AT&T’s Uniﬁed Network Management Architecture (UNMA) tools for end-to-end control of your information network.
Page 190 8-36 DATA NETWORK ADMINISTRATION _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 191 9. DATA COMMUNICATIONS CONFIGURATIONS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Chapter 8 described how DTEs and LANs can communicate through your communications system. In addition, it told you how your communications system could communicate over greater distances using any of the data services.
Page 192: Dsc And Psc Connections
DATA COMMUNICATIONS CONFIGURATIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DSC AND PSC CONNECTIONS The dedicated switched connection (DSC) is a feature that provides a dedicated path using circuit-switched facilities on the System 85 (R2V4) and Generic 2 communications system; the permanent switched connection (PSC) offers a similar capability on the System 75 and Generic 1.1 communications systems.
Page 193: Figure 9-1. Dedicated/Permanent Switched Connections — Conﬁgurations (Sheet 1-Or 2)
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ ORIGINATING DATA MODULE HIGH-USAGE DATA TERMINAL A. SYSTEM 75 OR GENERIC 1 - PSC USING STANDARD BUILDING WIRING MODEM B. SYSTEM 85 (R2V3) TO SYSTEM 85 (R2V3 OR V4) OR GENERIC 2 OVER DS1 HIGH-USAGE DATA TERMINAL MULTIPLEXER...
Page 194 DATA COMMUNICATIONS CONFIGURATIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ HOST MADU COMPUTER INTERFACE (24TH-CHANNEL OR ISDN PRI MOS SIGNALING COMMUNICATION TYPE MUST BE AVD OR DATA) D. SYSTEM 75, SYSTEM 85, GENERIC 1, OR GENERIC 2 - PSC/DSC USING PRIVATE SYSTEM 85, R2V3 MODEM DCIU...
Page 195: Sna Node Connections
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ SNA NODE CONNECTIONS You can use your communications system to connect the nodes in your SNA network. To do this, you use a dedicated connection (DSC or PSC) through the communicating switches. A workable conﬁguration is shown in ﬁgure 9-2, although other conﬁgurations are possible.
Page 196: Connections Through Public Or Private Data Networks
DATA COMMUNICATIONS CONFIGURATIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ CONNECTIONS THROUGH PUBLIC OR PRIVATE DATA NETWORKS You can connect your local communications systems with each other through DS1 facilities over public or private data networks for ﬁle transfers, video teleconferencing, image processing, and FAX transmittal. Connecting the sites through a DS1 facility allows you to take full advantage of the DS1 capacity —...
Page 197: Image Processing
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ ACCUNET MPDM* ACCUNET MPDM* PICTURETEL *Also called MPDM/M1*. Figure 9-4. A Possible Teleconferencing Conﬁguration Image Processing CAD/CAE and medical imaging applications may require the transmittal of an image cross-country. These applications can use either public, switched ( Digital Network) or private, nonswitched ( transmission from site to site.
Page 198: Figure 9-5. A Possible Imaging Conﬁguration
DATA COMMUNICATIONS CONFIGURATIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ OPTICAL SERVER SCANNER FILM SCANNER OPTICAL STORAGE IMAGE GATEWAY PROCESSOR Figure 9-5. A Possible Imaging Conﬁguration 9.6/56/64 KBPS GROUP 3/4 ACCUNET MPDM 2.4/4.6 KBPS Figure 9-6. A Possible FAX Conﬁguration GATEWAY T1 MUX DATA NETWORK...
Page 199: Related Documents
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ GENERAL Operation User’s Guide — DDM-1000 (363-206-100) Z3A Asynchronous Data Unit (555-401-701) II 740/741 User’s Manual (999-100-289IS) DATAPHONE ESF T1 Channel Service Unit User’s Manual (999-100-305) User’s Guide — Channel Division Multiplexer (999-300-190IS) User’s Guide — Digital Terminal Data Module (999-700-027IS) User’s Guide —...
Page 200 RELATED DOCUMENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ AT&T DR23N Marketing Guide (350-068) D4 Channel Bank Description (365-170-100) Switched-On Data (451-400) Digital Multiplexed Interface Technical Speciﬁcation Issue 3.1 (500-029) PC/PBX Platform Installation and Reference (555-016-101) PC/ISDN Platform Installation and Reference (555-016-102) PC/PBX Release 3 Documentation Set (555-016-715) 7400A Data Module (555-020-706) 7400B Data Module (555-020-707)
Page 201 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ A Guide to Premises Distribution (555-400-021) Multiple Asynchronous Data Unit User Manual (555-401-702) Z3A Asynchronous Data Unit Product Manual (555-401-708) Introduction to ACCUMASTER Private Network Management (5CE-054) 551 T1 Channel Service Unit User’s Manual (999-100-189IS) 718 Stat Mux Reference Manual (999-100-232) 719 Networker Reference Manual (999-100-235) DATAPHONE...
Page 202 RELATED DOCUMENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DIMENSION Administration Administration and Maintenance Manual — System Administration Procedures (500-915 to 917) RMATS-1 — Description, Operation, Maintenance, and Installation (554-010-130) Feature Translations for DIMENSION Feature Translations for DIMENSION Customer Administration Center (700-378) Data Switching —...
Page 203 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ System 75, System 85, and Trunk Signaling and Transmission ( 555-025-205) SYSTEM 75 AND GENERIC 1 Administration PC/PBX Connection Switch Administration for Packages 1, 3, and 5 (555-016-501) System 75 Implementation Manual Release 1 Version 3 (555-200-652) Application Notes —...
Page 204 RELATED DOCUMENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Communications System and System 75 and System 85 Terminals and Adjuncts (555-015-201) DEFINITY Communications System and System 75 and System 85 DS1/DMI/ISDN PRI (555-025-101) DEFINITY System 75 and 85 Connectivity Certiﬁcation Multivendor Conﬁgurations (555-025-901) System 75/85 to ISN Connectivity and Integration Guide (555-035-202) System 75 R1V3 To 4ESS With System 75 R1V3 to 4ESS with...
Page 205 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Sales Data Switching Sales Guide (555-035-001) Data Switching Applications (555-035-002) Service Communications System and System 75 and System 85 Terminals and Adjuncts DEFINITY Installation and Tests (555-015-104) ISDN Terminal Installation and Tests (555-021-101) SYSTEM 85 AND GENERIC 2 Administration PC/PBX Connection Switch Administration for Packages 1, 3, and 5 (555-016-501) System 85 7103A Voice Terminal Application Notes (555-102-511)
Page 206 RELATED DOCUMENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ System 85 7434 Voice Terminal Application Notes (555-109-003) System 85 7400A Data Module Host Access Operation Application Notes (555-109-004) System 85 7400A Data Module External Modem Pooling Operation Application Notes (555-109-005) Visual Maintenance and Administration Panel (VMAAP) Switch Administration and Maintenance with a UNIX PC (585-206-701) Visual Maintenance and Administration Panel (VMAAP) Switch Administration and Maintenance with a 3B2 Computer (585-206-703)
Page 207 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ System 85 R2V4 to 740 Multiplexer (555-037-214) System 85 R2V4 to CSU (555-037-215) System 85 R2V4 to DR23n Microwave (555-037-216) System 85 R2V4 to 4ESS Via ISDN PRI Access (555-037-232) System 85 R2V4 to DEFINITY System 85 R2V4 to System 75 R1V3 With DCS (555-037-235) System 85 R2V4 to ESF T1 CSU (555-037-236)
Page 208 A-10 RELATED DOCUMENTS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 209: The Need For Synchronization
B. SYNCHRONIZATION OF DIGITAL FACILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The DS1 transmit and receive buffers (for Generic 1 and Generic 2) operate from a single external or internal clock. Each digital switch can accommodate multiple DS1 or T1 spans that link multiple switches. These may include both ISDN-PRI and DS1 links.
Page 210: Figure B-1. Options For Synchronization
SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ systems connected by T1-carrier facilities. For this arrangement, the transmitting portion of each channel bank independently determines the clock rates. The receiving portion of each channel bank derives its clock from the incoming digital bit stream. In this arrangement, the channel banks convert the received digital signal directly to analog, and there is no requirement that the two clock frequencies precisely match as the channel bank does not interface to another digital system.
Page 211: Synchronization Hierarchy
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Notice in ﬁgure B-1-B, Options for Synchronization, that the overrun or underrun problem can be prevented by forcing the channel bank transmitter to operate at the same clock rate as the receive portion of the channel bank.
Page 212: Figure B-2. Synchronization Hierarchy
SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ For the hierarchical method, a node containing a very stable reference frequency is identiﬁed as the source or master reference. The master reference is transmitted to another node that is synchronized (slaved) to this master reference.
Page 213 SYNCHRONIZATION OF DIGITAL FACILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ synchronized together. However, to provide higher quality synchronization performance, stratum-3 clocks are currently being used with some customer-premises equipment. Because of recent changes within the synchronization hierarchy, stratum-4 clocks are now deﬁned as stratum-4E or stratum-4.
Page 214 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ The public digital network nodes and services that the AT&T private digital switches and digital terminal products can connect to are as follows: Digital serving ofﬁce (DSO), also called a digital toll ofﬁce, such as a 4ESS Digital central ofﬁce (DCO) such as a 5ESS Digital-access and cross-connect system (DACS) The AT&T private digital network nodes are the following:...
Page 215: Figure B-3. Stratum Levels For The Synchronization Hierarchy
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ AT&T STANDARD REFERENCE FREQUENCY SYSTEM DEFINITY 75 OR 85 G1 OR G2 DEFINITY ... . SYSTEM G1 OR G2 LEGEND DIGITAL TRANSMISSION FACILITY PRIMARY FREQUENCY REFERENCE .
Page 216: Figure B-4. Scs (Generic 2)
SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ TN463 CIRCUIT PACK STRATUM 4 HIGH ACCURACY CLOCK BACKPLANE CABLE TO PRIMARY MODULE MAIN PRIMARY DS1 REFERENCE CONTROL PHASE INTERFACE LOCKED (NOTE) TMS CLOCK LOOP OSCILLATOR BACKPLANE CABLE TO SECONDARY SECONDARY DS1 REFERENCE INTERFACE...
Page 217: Figure B-5. Duplicated Synchronization Architecture And Cross Coupling
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ System 85 or Generic 2 with a duplicated architecture and cross-coupled cables. PRIMARY INTERFACE SECONDARY PRIMARY SECONDARY INTERFACE Figure B-5. Duplicated Synchronization Architecture and Cross Coupling The TN767 is a DS1 circuit pack for a universal module; the ANN11 is a DS1 circuit pack for a traditional module.
Page 218 B-10 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Red alarm means that two out of four (or worse) framing patterns were received. Slip rate of selected DS1 facilities (with respect to the primary reference) exceeds a given threshold Misframes at the primary reference exceed a given threshold Reception of a yellow alarm (or a blue alarm for R2V4, 1.1 and later) Health of SCS circuit pack...
Page 219: Changes To The Scs Software Made Available Via Software Patches
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The LED in position #5 refers to the secondary DS1 reference. The LED is OFF if a synchronization signal is present and the SCS is capable of locking. The #5 LED is ON if an error condition exists and the synchronization cable is present.
Page 220: Figure B-6. Tone-Clock Synchronizer (Nonduplicated, Generic 1)
B-12 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ STRATUM 4 ACCURACY CLOCK EXTERNAL PRIMARY SYNC REFERENCE SOURCE SECONDARY EXTERNAL SYNC REFERENCE SOURCE Figure B-6. Tone-Clock Synchronizer (Nonduplicated, Generic 1) System 75 and Generic 1 Synchronization Software Operation System 75 and Generic 1 synchronization software differs slightly from System 85 and Generic 2 because of architectural differences;...
Page 221 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The TN768 and TN780 circuit packs contain edge-mounted LEDs. These LEDs indicate the following status sequences: Yellow LED is on 2.7 seconds and off 0.3 seconds — the tone-clock synchronizer is in ‘‘active’’ mode and a DS1 is being used as a synchronization reference.
Page 222 B-14 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ With automatic reference switching enabled, most Generic 1 error counters are decremented by 1 every 15 minutes and initialized to zero on reaching the threshold value. The following conditions cause an ofﬂine reference to be restored to online (items 2 through 7 apply only when the stratum-3 option is not used).
Page 223: Figure B-7. Public-Network External Clock
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ and secondary references also apply to these references. For System 85 and Generic 2, all functions previously performed by SCS synchronization software are now provided external to the switch — by the external clock. Furthermore, the switch does not know which reference (1 or 2) is online nor can the switch change from one reference to the other.
Page 224: Figure B-8. External Clock
B-16 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ STRATUM 3 REFERENCE #1 CLOCK INPUT PHASE BUILD STRATUM 3 CLOCK REFERENCE #2 INPUT -48VDC A SWITCH -48VDC B ALARM INTERFACE RETURN Private network applications that do not have digital connections to stratum-3 or better reference sources will not provide the Reference 1 and Reference 2 inputs or the clock-input #1 and clock-input #2 circuit packs.
Page 225: Figure B-10. External-Clock Duplicated Synchronization
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ COMPOSITE CLOCK OUTPUT A COMPOSITE CLOCK CONVERTER COMPOSITE CLOCK OUTPUT B NOTE 2 NOTES: 1. Alarm signals are cabled to the cross-connect ﬁeld. For System 85 and Generic 2, they are then cross-connected and cabled back to the TN442C or external alarm interface.
Page 226: Network Synchronization And Engineering
B-18 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ NETWORK SYNCHRONIZATION AND ENGINEERING The primary goals of network synchronization are: To keep each digital network node reliable To make sure that each digital termination can meet the network objectives With the growth in the number of digital facilities and the demands that today’s applications place on these facilities, designing a proper synchronization plan has become a complex and crucial process.
Page 227: Figure B-11. External And Internal Reference Levels
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ EXTERNALLY REFERENCED NODES INTERNALLY REFERENCED NODES DIGITAL TRANSMISSION FACILITY PRIMARY FREQUENCY REFERENCE Figure B-11. External and Internal Reference Levels For externally referenced nodes, the operating company personnel will specify what the source of timing is on those links.
Page 228: Figure B-12. Nonpublic Network Without Digital Switches
B-20 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ If there are one or more clocks in the network at the lowest stratum level, the following steps can be taken to determine the clock that should become the network reference clock source. Step 1: If there is only one digital switch in the network, that switch is to be the network reference clock master.
Page 229: Figure B-13. Proper Use Of Backup Facilities
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RULE 2: A node may use a facility as a backup only if the node at the other end is not using that same facility as a backup. EXAMPLE FOR RULE 2 Figure B-13, Proper Use of Backup Facilities, illustrates an application of rule 2 and proper use of a backup facility between nodes A and C.
Page 230: Figure B-14. Improper Use Of Backup Facilities
B-22 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ ........
Page 231: Figure B-15. Optimal Diverse Routing
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Facility rank ordering is generally based on limited technical and operational information. It is recommended that facility selections be based on local ﬁeld experience where available. RULE 4: Where possible, the routes for all primary and secondary synchronization facilities should be diverse. EXAMPLE FOR RULE 4 Figure B-15, Optimal Diverse Routing, explains the optimal conﬁguration when rule 4 is used.
Page 232: Figure B-16. Less Than Optimal Diverse Routing
B-24 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ ........
Page 233: Figure B-17. Excessive Cascading
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ ......SYNCHRONIZATION OF DIGITAL FACILITIES DIGITAL TRANSMISSION FACILITY PRIMARY FREQUENCY REFERENCE SECONDARY (BACKUP) FREQUENCY REFERENCE Figure B-17.
Page 234: Figure B-19. Excessive Synchronization From One Node
B-26 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ RULE 7: The number of nodes receiving synchronization reference from any given node should be minimized. EXAMPLE FOR RULE 7 Figure B-19, Excessive Synchronization from One Node, shows an excess of synchronization from one node.
Page 235: Figure B-20. Minimized Synchronization From One Node
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ ....DIGITAL TRANSMISSION FACILITY PRIMARY FREQUENCY REFERENCE ....Figure B-20.
Page 236: Availability Of Synchronization Sources
B-28 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ AVAILABILITY OF SYNCHRONIZATION SOURCES Misconception 1 The local exchange company (LEC) can always provide the synchronization source. Fact 1 The LECs are not always subscribers to the AT&T reference frequency. Many end ofﬁces still use analog switches and D4-channel banks.
Page 237: Conclusions On Synchronization
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ CONCLUSIONS ON SYNCHRONIZATION Make no assumptions regarding synchronization. Reverify items such as the availability of a synchronization source, the clock stratum, and compatibility of every T1 span. The best guarantee is written conﬁrmation that the local exchange carrier, AT&T Communications, or other vendor will either synchronize to a System 75, System 85, Generic 1, Generic 2, or provide an appropriate synchronization reference.
Page 238 B-30 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ only mode DS1s should not be used to determine the health of a clock reference (that is, they would tend to make the reference appear to be in better condition than it may be). Line-only mode DS1s should not be used as system clock references unless it is known for certain that the incoming DS1 is locked to the AT&T reference frequency.
Page 239 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Trunk-Mode Interface (ISDN-PRI + Robbed Bit) (TN767) Since it is expected that a trunk mode DS1 would terminate at a class-5 or higher CO or at another switch, the trunk interface should be suitable for use as a primary or secondary clock reference (or to be the timing master for another switch).
Page 240 B-32 SYNCHRONIZATION OF DIGITAL FACILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 241: Frequently Used Terms
C. TRUNKING TERMS AND CAPABILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ This appendix contains a list of trunking-related terms. The terms are listed in alphabetical order and should serve as a supplement to the glossary. Also included are several pages of tabular data that identify the various trunk types, their signaling characteristics, and recommended options for the distant switch.
Page 242 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Alerting Signals Functions to establish the way information is sent and received across trunks, once they are seized. For tie trunks, there exist ﬁve different alerting signals. They are referred to as: Automatic, Delay-Dial, Dial-Tone, Immediate Start, and Wink Start.
Page 243 TRUNKING TERMS AND CAPABILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ CCSA (or Common Control Switching Arrangement) A private network conﬁguration in which switching is provided by one or more CO switches. Typically, these CO switches may be shared by other private networks as well as by the public switched telephone network.
Page 244 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Delay-Dial The method of alerting whereby the originating switch waits for the terminating switch to acknowledge (via a start-dial signal) that it is ready to receive the address digits. Digit sending begins upon receiving the end of the delay-dial signal.
Page 245 TRUNKING TERMS AND CAPABILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Derived E&M Lead Signaling A signaling interface arrangement where the basic E&M interface is modiﬁed so that the E&M leads derive/superimpose either simplex, duplex, or composite type signals. Designed Trunks ‘‘Designed trunks’’...
Page 246 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Direct Access Refer to ‘‘Special Access Connections.’’ EPSCS (or Enhanced Private Switched Communications Service) A private network conﬁguration in which switching is provided by one or more CO switches. These CO switches may be shared by other private networks as well as the public switched telephone network, just like CCSA networks.
Page 247 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ (4) All out-of-building (inter-building) applications should have lightning protection optioned. Note: For System 85 and Generic 2 traditional module trunks, the method of selecting E&M options involves conﬁguring DIP switches on the SN circuit pack. For System 75, Generic 1, and Generic 2 universal module trunks, proper option selection involves administering the correct software type option (e.g., Type 1 standard, Type 1 compatible, or Type 5) and conﬁguring the circuit pack DIP switches (Unprot/Prot as well as Simplex/E&M).
Page 248 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Glare A problem that can occur with any 2-way trunks. Glare occurs when both ends seize the same trunk circuit simultaneously. Glare is more likely to occur with loop start than other types of trunks. Glare Detection System 85 (R2V4) and the Generic 2 communications system are capable of both detecting and resolving occurrences of glare in (a) ISDN trunks and (b) all other trunk types which use the ‘‘true wink start’’...
Page 249 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ (3) If the other entity is a PBX, either encode may be used by mutual agreement; however, they must be opposite for the trunk to work at all. Ground Start The supervisory signaling method whereby the originating switch grounds the ring lead (as a signal, to the distant switch that it wishes to seize the trunk).
Page 250 C-10 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ 100-milliseconds——for PBX switches. DIMENSION Interdigit Time-out The maximum number of seconds that the switch can wait from one digit to the next digit before a time-out occurs and a retry is required. This is a switch parameter related to call origination. The DIMENSION use 10 seconds as the time-out.
Page 251 C-11 TRUNKING TERMS AND CAPABILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Main PBX In a main—satellite/tributary communications network, it is the primary (main) node that handles all trunk trafﬁc for the connected satellite and tributary switches. Main-Satellite Trunks For the System 85, Generic 2, and PBX, this term refers to the 70 series of trunk types that are DIMENSION used for connecting a MAIN switch to a Satellite or Tributary switch.
Page 252 C-12 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Note: System 75 R1V1 DOES NOT SUPPORT precise dial tone. Therefore, it is recommended that the distant switch be optioned to provide the R1V1 switch with a dc signal (e.g., a wink or delay-dial) as the indication to begin digit sending.
Page 253 C-13 TRUNKING TERMS AND CAPABILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Signaling Type With System 85 (R2V4) and the Generic 2 communications system, the switch provides the capability to administer a different signaling type (e.g., E&M, ground start, etc.) from that implied by or defaulted by the trunk type.
Page 254 C-14 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Touch-Tone Signaling Refer to DTMF. Trunk Type (or trunk group type) PBX, System 85, and the Generic 2 communications system the term ‘‘trunk type’’ is a 2- DIMENSION or 3-digit number that is associated with certain software routines. These software routines (each trunk type) provide a unique signaling sequence that enables the trunk circuit pack to interface to a particular trunk service/feature.
Page 255 C-15 TRUNKING TERMS AND CAPABILITIES _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Note: Previously, most switch implementations of the universal trunk type have not actually timed for a precise wink signal. However, they do provide dial-tone detection for subnet trunk groups. With System 85 (R2V4) and Generic 2, E&M trunk types 41, 43, 46, and 47 will provide a ‘‘true’’...
Page 256 C-16 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ SUGGESTIONS AND HELPFUL HINTS (1) Given a choice of multiple trunk supervision methods—E&M generally works best. (2) Historically, those types of features and trunk services provided by class 5 analog COs have required either Ground Start or Reverse Battery trunk supervision.
Page 257 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ TRUNKING CHARACTERISTICS TABLE D ——identiﬁes the DEFAULT supervision option on the Generic 2 for the associated trunk group type and the only option for R2V3 and earlier releases. -## ——identiﬁes a 1- or 2-digit number that corresponds to a particular signaling type.
Page 258 C-18 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ FOR EACH "SWITCH A" TRUNKING OPTION (LISTED BELOW) — REFER TO THE CORRESPONDING RECOMMENDED "SWITCH B" TRUNK OPTIONS (RIGHT FACING PAGE). GROUP/CALL TYPE DIREC- TION GENERIC 2, SYSTEM 85, OR DIMENSION PBX 12/APLT (Notes 1&2)
Page 259 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RECOMMENDED TRUNK OPTIONS — OTHER OPTIONS MAY WORK FOR SOME APPLICATIONS; HOWEVER THESE OPTIONS SHOULD ALWAYS WORK. GROUP/CALL TYPE GENERIC 2, GENERIC 1, 4 ESS SYSTEM 85, OR SYSTEM 75 DIMENSION PBX E&M, DTMF, WINK E&M, DTMF,...
Page 260 C-20 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ FOR EACH "SWITCH A" TRUNKING OPTION (LISTED BELOW) — REFER TO THE CORRESPONDING RECOMMENDED "SWITCH B" TRUNK OPTIONS (RIGHT FACING PAGE). GROUP/CALL TYPE DIREC- TION GENERIC 2, SYSTEM 85, OR DIMENSION PBX 18/CO 19/CO...
Page 261 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RECOMMENDED TRUNK OPTIONS — OTHER OPTIONS MAY WORK FOR SOME APPLICATIONS; HOWEVER THESE OPTIONS SHOULD ALWAYS WORK. GROUP/CALL TYPE GENERIC 2, GENERIC 1, 4 ESS SYSTEM 85, OR SYSTEM 75 DIMENSION PBX Notes: 11. This trunk type and optional signaling arrangement may be used to build a "Special Access" trunk group. A typical application for this trunk type/signaling arrangement is to support MEGACOM Service.
Page 262 C-22 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ FOR EACH "SWITCH A" TRUNKING OPTION (LISTED BELOW) — REFER TO THE CORRESPONDING RECOMMENDED "SWITCH B" TRUNK OPTIONS (RIGHT FACING PAGE). GROUP/CALL TYPE DIREC- TION GENERIC 2, SYSTEM 85, OR DIMENSION PBX 26/WATS 27/WATS...
Page 263 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RECOMMENDED TRUNK OPTIONS — OTHER OPTIONS MAY WORK FOR SOME APPLICATIONS; HOWEVER THESE OPTIONS SHOULD ALWAYS WORK. GROUP/CALL TYPE GENERIC 2, GENERIC 1, 4 ESS SYSTEM 85, OR SYSTEM 75 DIMENSION PBX E&M DTMF, WINK DTS* E&M, DTMF WINK...
Page 264 C-24 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ FOR EACH "SWITCH A" TRUNKING OPTION (LISTED BELOW) — REFER TO THE CORRESPONDING RECOMMENDED "SWITCH B" TRUNK OPTIONS (RIGHT FACING PAGE). GROUP/CALL TYPE DIREC- TION GENERIC 2, SYSTEM 85, OR DIMENSION PBX 35/TIE 36/TIE...
Page 265 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RECOMMENDED TRUNK OPTIONS — OTHER OPTIONS MAY WORK FOR SOME APPLICATIONS; HOWEVER THESE OPTIONS SHOULD ALWAYS WORK. GROUP/CALL TYPE GENERIC 2, GENERIC 1 4 ESS SYSTEM 85, OR SYSTEM 75 DIMENSION PBX MIOPNOP NO DIGITS MIOPNOP WITH DIGITS MIOPNOP...
Page 266 C-26 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ FOR EACH "SWITCH A" TRUNKING OPTION (LISTED BELOW) — REFER TO THE CORRESPONDING RECOMMENDED "SWITCH B" TRUNK OPTIONS (RIGHT FACING PAGE). GROUP/CALL TYPE DIREC- TION GENERIC 2, SYSTEM 85, OR DIMENSION PBX 43/TIE 44/TIE...
Page 267 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RECOMMENDED TRUNK OPTIONS — OTHER OPTIONS MAY WORK FOR SOME APPLICATIONS; HOWEVER THESE OPTIONS SHOULD ALWAYS WORK. GROUP/CALL TYPE GENERIC 2, GENERIC 1, 4 ESS SYSTEM 85, OR SYSTEM 75 DIMENSION PBX DTMF, WINK MIOPNOP DTMF, WINK DTMF,...
Page 268 C-28 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ FOR EACH "SWITCH A" TRUNKING OPTION (LISTED BELOW) — REFER TO THE CORRESPONDING RECOMMENDED "SWITCH B" TRUNK OPTIONS (RIGHT FACING PAGE). GROUP/CALL TYPE DIREC- TION GENERIC 2, SYSTEM 85, OR DIMENSION PBX 50/RA 57/CAS RLT-OUTGOING...
Page 269 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RECOMMENDED TRUNK OPTIONS — OTHER OPTIONS MAY WORK FOR SOME APPLICATIONS; HOWEVER THESE OPTIONS SHOULD ALWAYS WORK. GROUP/CALL TYPE GENERIC 2, GENERIC 1, 4 ESS SYSTEM 85, OR SYSTEM 75 DIMENSION PBX DTMF, WINK, MIOPNOP (MAIN) (BRANCH)
Page 270 C-30 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ FOR EACH "SWITCH A" TRUNKING OPTION (LISTED BELOW) — REFER TO THE CORRESPONDING RECOMMENDED "SWITCH B" TRUNK OPTIONS (RIGHT FACING PAGE). GROUP/CALL TYPE DIREC- TION GENERIC 2, SYSTEM 85, OR DIMENSION PBX 101/DATA ANALOG DATA...
Page 271 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ RECOMMENDED TRUNK OPTIONS — OTHER OPTIONS MAY WORK FOR SOME APPLICATIONS; HOWEVER THESE OPTIONS SHOULD ALWAYS WORK. GROUP/CALL TYPE GENERIC 2, GENERIC 1, 4 ESS SYSTEM 85, OR SYSTEM 75 DIMENSION PBX DTMF, WINK 109 (R2V4/G2) TRUNKING TERMS AND CAPABILITIES SWITCH B...
Page 272 C-32 TRUNKING TERMS AND CAPABILITIES _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 273: Communications Protocols
D. COMMUNICATIONS PROTOCOLS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ A protocol is a set of rules for how transmissions are to be initiated and maintained between communication points. These rules are conventions that govern the syntax and sequencing of messages. Several domestic and international organizations formulate standards for data communications protocols.
Page 274: Osi Model
COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ OSI MODEL To provide a model through which all protocols could be classiﬁed and studied, the International Organization for Standardization (ISO) created the Open Systems Interconnection (OSI) architecture. The OSI model has seven layers (see Figure D-1). Physical Layer The physical layer, or layer 1, covers the physical interface between devices and the rules by which bits are passed.
Page 275 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ COMMUNICATIONS PROTOCOLS LEVEL 7 APPLICATION LAYER LEVEL 6 PRESENTATION LAYER LEVEL 5 SESSION LAYER LEVEL 4 TRANSPORT LAYER LEVEL 3 NETWORK LAYER LEVEL 2...
Page 276: Figure D-1. Osi Reference Model
COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Figure D-1. OSI Reference Model...
Page 277: Standard Protocols
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Session Layer The session layer, or layer 5, provides a mechanism for controlling dialogue between applications. It establishes, manages, and terminates connections between cooperating applications. Presentation Layer The presentation layer, or layer 6, provides independence to the application processes from differences in syntax.
Page 278 COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table D-1. Some CCITT Digital Standards Name International user classes of service in public data networks International user services and facilities in public networks General structure of signals of international alphabet no. 5 code for data transmission over public data networks X.20 Interface between data terminal equipment (DTE) and data circuit-...
Page 279 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table D-2. Some CCITT Analog Standards Name International alphabet no. 5 General structure of signals of international alphabet no. 5 code for data transmission over public telephone networks Standardization of data signaling rates for synchronous data transmission in the general switched telephone network Standardization of data signaling rates for synchronous data transmission over leased telephone-type circuit...
Page 280 COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ TABLE D-2. Some CCITT Analog Standards (Continued) Name V.29 9600 bps modem standardized for use on point-to-point leased telephone-type circuits V.35 Data transmission at 48 kilobits per second using 60-108 kHz group band circuits V.54 Loop test devices for modems...
Page 281: Figure D-2. Isdn Protocols
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Application Presentation End-to-end user signaling Session Transport Call control Network I.451 Data link LAP-D (I.441) Physical Signal Adapted from: Data and Computer Communications, by William Stallings, Macmillan Publishing Co., N.Y., 1988 Other Common Standards In addition to standards formulated by the CCITT, many other standards are common.
Page 282 D-10 COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ ADCCP (Advanced data communications control procedures) — A protocol developed by ANSI, and later adopted by the National Bureau of Standards, the Federal Communications Standards Committee, and the Defense Department. There are virtually no differences between HDLC and ADCCP. See Table 1-4 for the names of some protocols that are commonly used at speciﬁc ISO layers.
Page 283 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The Bell standard for X.25 (BX.25) The primary rate interface standard is the ISDN standard for communication along a DS1 facility. AT&T has its own implementation of this standard. For further details, see the Generic 2 and System 75 and System 85 DS1/DMI/ISDN PRI Reference manual (555-025-101).
Page 284 D-12 COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ —Requires a ‘‘circuit-switched’’ transmission facility Applications: There are two uses of mode 0. They are: (a) 8-bit PCM voice (no robbed-bit or inband signaling is allowed) (b) 64-kbps user data. Description: With 64-kbps data, nothing is known about the structure of the information in the channel.
Page 285: Figure D-3. Data Mode 1 With Dcp And Ds1/Dmi/Bos Frame Multiplexing Arrangements
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ data frames are multiplexed into a DCP and DS1 frame. The state of the status bit along with its transition from one frame to another frame is used to convey the state of the following RS-449/V.35 signal leads: Request to Send (transmit) Clear to Send...
Page 286 D-14 COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Data Mode 2 Capabilities: —Low, 300, 1200, 2400, 4800, 9600, or 19.2 kbps —Full- or half-duplex operation —Asynchronous transmission of user data, or —Synchronous transmission (with clock independence) —Requires a ‘‘circuit-switched’’ transmission facility Note: The low-speed option permits operation at any data rate from 0 to 1800 bps.
Page 287: Figure D-4. Data Mode 2 Frame Structure
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ FLAG 0 1 1 1 1 1 1 0 Figure D-4. Data mode 2 Frame Structure Note: For asynchronous data, the SCA ﬁeld is left spare. The data/control ﬁeld is a variable length ﬁeld. Length of the block is automatically determined by the data rate and the desire to minimize transit delay.
Page 288 D-16 COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Also, the update messages support three special control functions. They are: BRK — remote break indicator RLR — remote loop request ACK — remote loop acknowledge Transmission errors are detected by checking the CRC checksum on receive. Errors are corrected by retransmitting the errored block(s).
Page 289: Figure D-5. Dcp Frame Format
_ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The DCP protocol physical level requires a 4-wire data link. Therefore, the data link must be composed of at least two twisted pairs. The physical interface may include additional wire pairs for spares and auxiliary power functions.
Page 290 D-18 COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Transmit Pair Receive Pair In terms of time sequence the DCP protocol was introduced with System 85 Release 1, the ISDN-BRI is ﬁrst available with System 85 R2V5. Therefore, the DCP protocol was the initial AT&T attempt to implement what was then the unspeciﬁed ISDN basic rate interface (BRI).
Page 291 D-19 COMMUNICATIONS PROTOCOLS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Physical Layer. This layer for BX.25 is compatible with the RS-232C and RS-449 standards. Data-Link Layer. At this layer, BX.25 uses a procedure is compatible with the (High-Level Data HDLC Link Control) procedure and is performed by ﬁrmware and by an chip on each of the DCIU...
Page 292 D-20 COMMUNICATIONS PROTOCOLS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Message, Packet, and Frame The units of information in BX.25 are the message, the packet, and the frame. Starting with the data that an application (e.g., on the 501CC) wishes to send to its remote peer (on the ) serving the local application prefaces the application data with a thereby forming a message.
Page 293 E. LEAD DEFINITIONS _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ This appendix provides tables that list the lead deﬁnitions for the most common physical interfaces.
Page 294 LEAD DEFINITIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table E-1. EIA RS-232C (V.28) LEADS/DEFINITIONS INTERCHANGE CIRCUIT — — — — CCITT LEAD DESCRIPTION EQUIVALENT (FUNCTION) CIRCUIT Protective Ground Transmitted Data Received Data Request to Send Clear to Send Data Set Ready Signal Ground/Common Ground Received Line Signal Detected —...
Page 295 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table E-2. EIA RS-232D (V.28) LEADS/DEFINITIONS INTERCHANGE CIRCUIT — — — — RL/CG CH/CI CCITT LEAD DESCRIPTION EQUIVALENT (FUNCTION) CIRCUIT — Shield Transmitted Data Received Data Request to Send Clear to Send DCE Ready Signal Ground/Common Ground Received Line Signal Detected —...
Page 296 LEAD DEFINITIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table E-3. EIA RS-449 (V.24) LEADS/DEFINITIONS INTERCHANGE CIRCUIT — — SD(A) ST(A) RD(A) RS(A) RI(A) CS(A) DM(A) TR(A) RR(A) TT(A) — SD(B) (Note) ST(B) (Note) RD(B) (Note) RS(B) (Note) RT(B) (Note) CS(B) (Note) —...
Page 297 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table E-4. EIA RS-366 LEADS/DEFINITIONS INTERCHANGE CIRCUIT LEAD DESCRIPTION (FUNCTION) Unassigned Digit Present Abandon Call and Retry Call Request Present Next Digit Power Indication Signal Ground — Unassigned Reserved for Testing –P Reserved for Testing —...
Page 298 LEAD DEFINITIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Table E-5. CCITT V.35 LEADS/DEFINITIONS CCITT INTERCHANGE CIRCUIT — — — BB(A) BB(B) DD(A) DD(B) DB(A) DB(B) BA(A) BA(B) DA(A) — DA(B) — — — — — — — — — — LEAD DESCRIPTION EQUIVALENT (FUNCTION)
Page 299 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Table E-6. EIA RS-232C (V.28) LEADS SUPPORTED FOR AT&T TERMINALS PC 6300/ PLUS (Note 2) (Note 5) (Note 5) (Note 5) (Note 10) LEGEND: Bidirectional Input Output (Number) Indicates a reference note (see next page). DTDM/ PDM/ PC 7300...
Page 300 LEAD DEFINITIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Notes: Notes: 1. The SN238 and TN726 circuit packs provide the same signal leads as the ADU/MADU. 2. This lead is ignored in MODE 2 operation. 3. These leads are tied together on this terminal. 4.
Page 301 F. NETWORKING FEATURES——AVAILABILITY MATRIX _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The following list compares the network features available in the AT&T private switching systems. In the list NA = NOT APPLICABLE; Y = YES; N = NO.
Page 302 NETWORKING FEATURES——AVAILABILITY MATRIX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ DIMENSION ‘‘ FEATURE Iss 1 AAR "Basic" Patterns Ordered by Increasing FRL? Conditional Routing Symmetrical Routing Enhanced Symmetrical Partitioning ARS "Basic" Access Codes — Single Access — Toll & Non-Toll Codes Overﬂow to DDD —...
Page 303 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ NETWORKING FEATURES——AVAILABILITY MATRIX (Contd) DIMENSION ‘‘ FEATURE Iss 1 Iss 3 Attendant Direct Trunk Group Selection Authorization Codes Algorithm Selection Pre-Select Auto Circuit Assurance Automatic Overﬂow — To DDD — Toll Warning Autovon Interface Hardware Interface Software Interface Attendant Access...
Page 304 NETWORKING FEATURES——AVAILABILITY MATRIX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ NETWORKING FEATURES——AVAILABILITY MATRIX (Contd) DIMENSION ‘‘ FEATURE Iss 1 Inter PBX Attendant Service ISDN PRI Bearer Capability Call-by-Call Service Selection Calling Party Name /Number Display Channel Negotiation, Retry, & Glare Resolution End-to-End ISDN Routing Negotiated Trunk...
Page 305 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ NETWORKING FEATURES——AVAILABILITY MATRIX (Contd) DIMENSION ‘‘ FEATURE Iss 1 Subnet Trunking (Note 8) Tandem Tie Trunk Switching Tie Trunk Access Trunk Identiﬁcation By Attendant (Note 9) Trunk Veriﬁcation By Attendant (Note 10) Trunk Veriﬁcation By Customer (Note 10) Trunk Veriﬁcation By Voice Terminal...
Page 306 NETWORKING FEATURES——AVAILABILITY MATRIX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 307 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ 4ESS number 4 electronic switching system 5ESS number 5 electronic switching system Automatic Alternate Routing Automatic Circuit Assurance Automatic Call Distribution action control point (for SDN) ADPCM adaptive differential pulse-code modulation asynchronous data unit alternate mark inversion APLT advanced private-line termination...
Page 308 AB-2 ABBREVIATIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ central ofﬁce cyclic redundancy check Centralized System Management customer service unit dial access code DACS digital access and crossconnect system data circuit-terminating equipment data communications equipment DCIU data communications interface unit distributed communications system DATAPHONE direct inward dialing digital multiplexed interface...
Page 309 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ extended trunk access electronic tandem network facsimile front end processor feature package 8 (for facility restriction level foreign exchange G1/G2 Generic 1/Generic 2 general-purpose port Gbps billion bits per second high accuracy clock HEHO head end hop off IEEE Institute of Electrical and Electronics Engineers...
Page 310 AB-4 ABBREVIATIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ MPDM modular processor data module MS/T main satellite/tributary network MTDM modular trunk data module Mbps million bits per second network control point (for SDN) network inward dialing Open Systems Interconnection pulse-amplitude modulation private branch exchange personal computer protocol converter...
Page 311 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Software-Deﬁned Network system management terminal Systems Network Architecture serving ofﬁce (for SDN) SW56 Switched 56 SW64 Switched 64 TEHO tail end hop off time slot interchange unit tandem tie trunk (network) Uniform Dial Plan (package) UNMA Uniﬁed Network Management Architecture VMAAP...
Page 312 AB-6 ABBREVIATIONS _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...
Page 313 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ 24th-channel signaling Digital signal level-1 (DS1) signaling in which the signaling for each of the ﬁrst 23 channels is multiplexed onto the 24th channel, thereby providing a full 64 kbps for user data on each of the ﬁrst 23 channels. Also called clear-channel signaling.
Page 314 GL-2 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ American National See ASCII. Standard Code for Information Interchange analog The representation of information by means of continuously varying physical quantities such as amplitude, frequency, phase, or resistance. analog voice terminals An analog voice terminal (telephone) receives acoustic voice signals and sends analog electrical signals along the line.
Page 315 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ AUDIX Standalone An AUDIX system that has no data link and allows AUDIX service to be provided in association with any communications system but with less functionality than when AUDIX is integrated via a data link with a communications system.
Page 316 GL-4 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ bearer capability A term used with Integrated Services Digital Networks (ISDNs) to identify the kinds of service that are requested or are available for a call. See also bearer-capability class. bearer-capability class A term used to identify the kind of trunk service required for a call.
Page 317 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ See basic rate interface. See binary synchronous communications. BX.25 An AT&T version of the CCITT X.25 protocol for data communications. BX.25 adds a fourth level to the standard X.25 interface. This uppermost level combines levels 4, 5, and 6 of the International Standards Organization (ISO) reference model.
Page 318 GL-6 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ class of service (COS) 1. On the System 75 and Generic 1, a number (0 through 15) that speciﬁes a group of feature-access permissions of a group of telephones. COS speciﬁes whether telephone users can activate certain features such as Automatic Callback and Call Forwarding —...
Page 319 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ The terms channel service unit and customer service unit are both abbreviated to CSU and are both synonymous with network channel- terminating equipment. See network channel-terminating equipment. customer provided Customer owned equipment that is not provided as part of the system but (premises) equipment is to be connected to it.
Page 320 GL-8 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ data communications An interface between the System 85 main processor (501CC) and AUDIX interface unit (DCIU) equipment, or (in a DCS conﬁguration) other switches. The DCIU consists of four circuit packs in the System 85 and Generic 2 common control carrier.
Page 321 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ See Direct Department Calling. See direct distance dialing. dedicated line Also known as a private or leased line. It is for the exclusive use of the leasing party. dedicated switched A feature that functions as a hardwired link between two ports on a connection (DSC) System 85 (R2V4) or Generic 2 communications system, providing a full- time line between the assigned endpoints.
Page 322 GL-10 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ digital multiplexed An interface that provides connectivity between a communications system interface (DMI) and a host computer or between two communications systems using digital signal level-1 (DS1) 24th-channel signaling. DMI provides 23 64-kbps data channels and 1 common signaling channel over a twisted-pair connection.
Page 323 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ direct outward dialing A feature that enables a communications-system telephone user to gain (DOD) access to the public network without the assistance of an attendant by dialing an access code and receiving a second dial tone. The user can then dial the desired public-network number.
Page 324 GL-12 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ end user The ultimate source or destination of information ﬂowing through a network. It may be an application program, an operator or a physical device medium (such as cards or tapes). Enhanced Uniform Call An Automatic Call Distribution (ACD) feature that provides, in System 85 Distribution (EUCD) R2V2, automatic connection of incoming calls to agents who have been...
Page 325 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ ﬁnal trunk group A last-choice trunk group that receives overﬂow trafﬁc and may receive ﬁrst-route trafﬁc. See also trunk group. ﬁrst-choice trunk group The group of trunks on a communications system that is chosen ﬁrst for a particular call.
Page 326 GL-14 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ See general-purpose port. half-duplex transmission A transmission system capable of carrying signals in both directions, but in only one direction at a time. handshaking A process that occurs after successful call setup but before actual data transmission between two data devices to ascertain whether their data- transmission parameters are set to permit successful data transmission.
Page 327 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ Integrated Services A public or private network that provides end-to-end digital connectivity Digital Network (ISDN) for all services to which users have access by a limited set of standard multipurpose user-network interfaces deﬁned by the CCITT. Through internationally accepted standard interfaces, ISDN provides digital circuit-switched or packet-switched connectivity within the network and links to other ISDNs to provide national and international digital...
Page 328 GL-16 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ listed directory number The listed number in a public directory for a communications system. An (LDN) incoming call to an LDN is usually answered by an attendant. local area network (LAN) A networking arrangement speciﬁcally designed for a limited geographical area.
Page 329 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ MPDM See modular processor data module. MTDM See modular trunk data module. mu-255 A type of code by which analog signals are encoded to digital signals. multiplexer A device used to combine a number of individual channels into a common bit stream for transmission.
Page 330 GL-18 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ Open Systems A logical model, consisting of seven levels of interfaces, created by the Interconnection (OSI) International Standards Organization (ISO) to show how interconnected reference model telecommunications systems should interface. See Open Systems Interconnection reference model. packet A group of bytes —...
Page 331 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ permanent switched On the System 75 and Generic 1, a capability that establishes and connection (PSC) maintains a continuous switched connection between two data endpoints. PSCs are automatically established when the communications system is started or restarted, and are maintained until the system becomes inactive.
Page 332 GL-20 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ protocol converter (PC) A device consisting of hardware, software, or a combination of both, that allows two systems, each using a different protocol, to communicate and exchange messages with each other. public network A network that is commonly accessible for local or long-distance calling.
Page 333 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ route advance A telecommunications routine that routes outgoing calls over alternate trunk groups when the ﬁrst-choice trunk group is busy. RS-232 A physical interface speciﬁed by the EIA. RS-232 transmits and receives asynchronous data at speeds of up to 19.2 kbps over cable distances of up to 50 feet.
Page 334 GL-22 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ switch Any kind of telephone switching system. See also communications system and ESS . synchronization The process in which proper phase alignment to a transmitter is made so that the beginning and end of a character, message, time slot, or frame can be readily identiﬁed for information retrieval.
Page 335 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ tip and ring Tip and ring are common nomenclature derived from old cord switchboard technology to differentiate between the two leads of an analog line or trunk. trunk A dedicated telecommunications channel between two communications systems or central ofﬁces (COs).
Page 336 GL-24 GLOSSARY _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ WATS (Wide Area A service that allows calls to certain areas for a ﬂat-rate charge based on Telecommunications expected usage. Service) WATS trunk A one-way outgoing telecommunications channel used to place a WATS call, or a one-way incoming telecommunication channel used to receive an 800-service call.
Page 337 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ 10-to-7 digit conversion 2-14 24th channel signaling 1-27 2-wire trunk C-1 3270C 8-6 4-wire link 7-5, D-17 4-wire trunk C-1 718 Stat Mux 1-34 719 Networker 1-34 7400A 8-6 7400B 8-6 7500B 8-6 800 service 1-36 AAR 2-5, 2-6, 2-7, 2-8, 2-11, 2-13, 4-4, 4-7, 4-8, 5-1, 5-13 ACA 6-15...
Page 338 IN-2 INDEX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ ARS 2-4, 2-7, 2-8, 2-14 plan 2-16 asynchronous data-module 8-5 Asynchronous Gateway Server 8-16 AT&T reference frequency B-28 attendant 1-37, 2-2, 4-1, 4-3, 4-8, 5-12, 6-23 control of trunk group access 6-15 transparent features 6-14 attendant-call-waiting 6-14 Audio Information Exchange (AUDIX) 6-19...
Page 339 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ compression—Contd BCM-3200 1-31 channel expansion multiplexer 1-31 conditional call routing count 2-10 conﬁguration main/satellite 4-2 main/tributary 4-3 connection dedicated 9-5 dedicated switched 6-4, 7-8, 9-2 dial-up 7-8 nailed-up 7-8, C-13 permanent switched 6-4, 7-8, 9-2 SNA node 9-5 special access C-13 controlled slip B-2...
Page 340 IN-4 INDEX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ dial tone C-5, C-11 alerting 1-40 dialing C-14 computer 7-10 terminal 7-9 basic 7-9 break signal 7-9 default 7-9 Hayes-AT 7-9 mnemonic 7-9 dial-repeating 1-40 DID 1-36, 4-2, C-5 digital telephones 1-7 facilities, synchronization of B-1 multiplexed interface 1-14, D-11 multiplexed interface with bit-oriented...
Page 341 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ ﬁber-optic transmission 1-32, 8-14 ﬁle transfer 8-22, 9-6 fractional T1 8-26 frame 1-24 D4 1-24, 1-27, 1-29 ESF 1-24, 1-27, 1-29 synchronization pattern 1-25 framing formats 1-24 free run ability B-4 frequency-division multiplexing 1-17 FRL 2-10, 2-13, 2-16 default 2-10 FT-1 1-32...
Page 342 IN-6 INDEX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ line-only-mode B-29 line-+trunk-mode B-30 link synchronization B-1 link-layer protocols D-2, D-9, D-19 listed directory number 4-1, 4-2, 4-3 local area network 7-2, 8-13 logical channel 6-3, D-19 long distance facilities 5-9 loop start 1-40 LOS B-9, B-13 LWC 6-18, 6-21, 6-24 M44 service 1-31...
Page 343 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ network—Contd synchronization—Contd plan—Contd example B-20 issues B-1 tandem tie trunk 1-36, 2-2, 3-1, C-13 tuning B-29 network-layer protocols D-2 NFAS 1-28 NID 4-2 node connections, cascade B-24 noise 1-6 number international 2-14 IXC 2-14 listed directory 4-1, 4-2, 4-3 local 2-14 OCU data port card 1-30...
Page 344 IN-8 INDEX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ protocols—Contd layer 2 1-11 link layer 1-11 network layer D-2 Open System Interconnect 1-11 OSI 1-11 physical interface 1-13 physical layer 1-11, 1-15, D-2, D-9 presentation layer D-5 PRI 1-13, D-11 RS-232C 1-13, 6-3 RS-449 1-13, 6-3 ACCUNET modiﬁcation kit 9-1...
Page 345 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ signaling—Contd address C-1 DTMF C-3 AVD 1-41 common channel signaling arrangement C-3 DMI BOS 1-27 DMI MOS 1-27 DX C-3 E&M 1-39, C-3, C-5, C-6 facility associated 1-28 ground start 1-39 inband 1-26 ISDN PRI 1-27 loop start 1-40, C-10 nonfacility associated 1-28 out-of-band C-11...
Page 346 IN-10 INDEX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ synchronous transmission B-1 system clock reference using Generic 1 B-30 using Generic 2 B-29 System 75 and Generic 1 synchronization architecture B-11 and Generic 1 synchronization software operation B-12 T1 carrier 1-6, 1-18, 1-32 compression 1-31 timing B-23 T1.5 service 8-26...
Page 347 _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ _ ______________________________________________________________________________________ trunk—Contd 4-wire C-1 800 service 1-36 analog 1-9, 1-15 APLT 1-38 application 1-35 auxiliary 1-10, 1-35, 1-37 CCSA 1-38 central ofﬁce 1-35 CO 1-10 communications type 1-41 connectivity 1-38 DID 1-10, 1-36, C-5 digital 1-9 DMI 1-40 DOD 1-36 DS1 1-10, 1-15, 1-41, 6-4, 7-8...
Page 348 IN-12 INDEX _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________ _ ___________________________________________________________________________________________________________________________...

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