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Summary of Contents for Allied Telesis CentreCOM AT-6870
- Page 1 Allied Telesyn International CentreCOM MAC Layer Bridge Models AT-6870 AT-6875 User Manual PN 613-10450-00...
- Page 2 © Copyright 1996 Allied Telesyn International Corp. All rights reserved. No part of this publication may be reproduced without prior written permission from Allied Telesyn International. Allied Telesyn reserves the right to make changes in specifications and other information contained in this document without prior written notice.
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Page 3: Statement
Statement U.S. Federal Warning: This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to Part 15 of FCC Rules. These Communications limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. -
Page 4: Notes
Statement die Berschtigung zur Uberprufung der Serie auf Einhaltung der Bestimmungen eingeraumt. Von benutzer zusammengestellte Systeme, die dieses Gerat beihalten, mussen den Bestimmungen von Vfg 243 entsprechen. Notes The following are examples of special notices used throughout this manual. They are Notes, Cautions, and Warnings. They are defined as follows: Note: This indicates a note of specific interest related to the immediate text in which it is found. -
Page 5: Table Of Contents
Table of Contents Statement ........................iii U.S. Federal Communications ....................... iii Canadian Department of Communications ..................iii Electrical Notice ............................iii German Class B............................iii Notes................................iv Table of Contents ......................v Overview ..........................1 CentreCOM MAC Layer Bridge ......................1 Features .............................. -
Page 6: Table Of Contents
Table of Contents IEEE 802.3/10BASE2 (Thin Ethernet)....................17 IEEE 802.3/10BASE5 (Thick Ethernet)..................... 17 Propagation.............................. 17 IEEE 802.3 Four Repeater Rule......................18 Network Frame Formats .................... 19 Power Cords and Plugs ....................21 Glossary ..........................23 Warranty and Service Information .................25... -
Page 7: Overview
Chapter 1 Overview CentreCOM MAC AT-6870 Learning Bridge Layer Bridge AT-6875 SNMP Manageable Learning Bridge IEEE 8023 Compliant Ethernet Compatible The CentreCOM Bridges allow two IEEE 802.3 sub-networks to be connected into a single network. Each sub-network may be IEEE 802.3 Ethernet or thin Ethernet. -
Page 8: Features
Overview The TCP/IP SNMP is supported by the AT-6875. The bridge can be monitored and manipulated by many SNMP compatible management stations. Several parameters of the AT 6875 can be managed under SNMP including custom filtering, static forwarding entries, and STP. Features Self-learning MAC layer bridges Filter at 25,000 PPS... - Page 9 AT-30xxTR Multiport Repeater Light Function Channel 1 Receiving Channel 2 Transmitting Channel 2 Receiving Table 1: AT-6870 Front Panel Back Panel The back panel contains the following elements, shown in Figure 2: IEC-320/CEE-22 compatible power connector. Channel 1 connector for Ethernet or IEEE 802.3 10BASE5. Channel 1 thin Ethernet coaxial connector.
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Page 10: Application Guidelines
Overview Application Guidelines Overcoming Physical This section shows how bridges can be used to overcome common physical limitations. The next section shows how to do this in such a way that Limitations network performance is improved. Maximum Network A bridge can be used to link several networks serially (see Figure 3) in the Length same way as a repeater is used. - Page 11 AT-30xxTR Multiport Repeater Placement of Bridges The key to effective use of a bridge is to find the Work Groups within your in a Network organization and to place bridges between the networks in different groups. Network traffic within each Work Group is isolated by a bridge and has no effect on the overall network.
- Page 12 Overview From Frames/Second (Average) 9000 1000 1000 1000 1000 9000 Table 2: Traffic Between Nodes In this case there are two clusters. The first contains nodes 1 and 2, and the second contains nodes 3 and 4. Within each cluster, the traffic levels are around 13000 frames per second, while the traffic between the groups is around 4000 per second.
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Page 13: Mixing Media
AT-30xxTR Multiport Repeater 2. As long as the backbone network is operating correctly, any fault within a Work Group has no effect on other Work Groups. 3. Network faults are isolated to a single Work Group and are therefore easier to find. Figure 7: A Backbone Network Mixing Media The AT-6870/ AT-6875 MAC layer bridge can also be used to interconnect... -
Page 14: Fault Tolerance And Isolation
Overview Fault Tolerance and A single large network has several problems relating to faults. Two are listed below: Isolation If the network fails all users lose connectivity. Because of the network size, it may take a long time to find the fault. Figure 9 shows the failure of a simple network. -
Page 15: Using Backup Bridges
AT-30xxTR Multiport Repeater Figure 11: Failure of a Backbone Network A bridged network is therefore inherently more fault tolerant, providing service to many users even when network components fail. This has the side effect of making it much easier to isolate the cause of the network fault. - Page 16 Overview The network depicted in Figure 12 would continue to operate if one of the bridges was turned off accidentally, or if a cable between one of the bridges and a network was unplugged. Figure 13: Advanced Use of Backup Bridges By using backup (or redundant) bridges, it is possible to design a network topology that is extremely resilient to failure.
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Page 17: Installation And Operation
AT-30xxTR Multiport Repeater Installation and Operation Unpacking Rough handling during shipping can damage electronic equipment. After you unpack the CentreCOM MAC Layer Bridge, check carefully for possible damage. If you notice any damage, contact the shipper. Direct any additional questions about damage to the distributor from whom the unit was purchased, or contact Allied Telesyn: Allied Telesyn International 950 Kifer Road... - Page 18 Overview Settings Figure 14: Location of Headers and Transformers Thin Ethernet Transformer . Each channel has a transformer IC component that is only for thin Ethernet operation. This component must be moved to a spare socket if thin Ethernet is not used. The placement of these transformers is given below in Table 3 Network Type Channel 1...
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Page 19: Operation
AT-30xxTR Multiport Repeater 1. Remove any transformer in position T4. 2. Install the transformer into position T4A. Configuring Channel 2 Note: Channel 2 is set at the factory to operate with Ethernet or IEEE 803.2 10BASE5. Setting Channel 2 for Thin Ethernet Operation: 1. - Page 20 Overview The network itself may be faulty. This can usually be checked independently of the bridge by establishing communication between two computers that are directly attached to the network. Finally, you should check that the bridge configuration matches the network attachments being used. Turn off the power and remove the power cord from the bridge.
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Page 21: Specifications
Chapter 2 Specifications Software Features Compliant with IEEE 802.1 STP specification UDP/IP protocol support Dynamic forwarding table creation SNMP network management agent Power-on diagnostics Custom filtering criteria Hardware Features Networks IEEE 802.3 10BASE5 compliant Ethernet version 1.0 and 2.0 compatible IEEE 802.3 10BASE2 (thinnet) Memory 512K EPROM 128K Frame Buffer RAM 32 bytes EPROM 512K system RAM... -
Page 22: Accessories
Specifications Accessories Part No. Description AT-RKMT-2 Rackmount kit for 19 in. rack AT-RKMT-3 Rack mount “ears” kit for 19 in. rack AT-1250 UL listed power cord ATBRKT-13 Cable strain relief... -
Page 23: Ieee 802.3 Quick Primer
Appendix A IEEE 802.3 Quick Primer IEEE 802.3 AUI Drop AUI or "drop cables" can be no longer than 50 meters (164 feet) each. Attachments may be made only to the cable ends at the 15 pin D-shell connector. AUI drop Cables cables may have a maximum 257ns propagation delay for computing the worst case propagation delay of a cable system. -
Page 24: Ieee 802.3 Four Repeater Rule
IEEE 802.3 Quick Primer IEEE 802.3 Four No more than four repeaters may be linked to connect five segments and no other attachments may be on the linking segments. If attachments are present on the Repeater Rule repeater coax link segments, then no more than two repeaters linking three segments may be configured. -
Page 25: Network Frame Formats
Appendix B Network Frame Formats The Ethernet and IEEE 802.3 specifications define slightly different frame header formats. Both Ethernet and IEEE 802.3 use two 6 byte source and destination addresses, but the following two byte field is interpreted as a packet type by Ethernet and as a packet length by IEEE 802.3. - Page 26 Network Frame Formats Note that this problem exists only at the MAC interface level, and is independent of the higher level protocols being used, such as TCP/IP. Therefore, systems which use Ethernet and IEEE 802.3, may not be able to communicate with each other even though they use the same higher level protocol.
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Page 27: Power Cords And Plugs
Appendix C Power Cords and Plugs A standard power supply cord is shipped with all units sold in the United States. For units shipped internationally, the customer must supply a power cord that meets the regulations of the country where the bridge is operated. - Page 28 Appendix D Glossary 10BASE5 - Also called thick Ethernet, 10BASE5 is a 10 Mhz, Baseband, 500 meter coaxial segment. The cable is also refered to as "yellow" cable. Cable impedance is 50Ω. Thick Ethernet cable is typically used as a trunk or backbone path of the network.
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Page 29: Glossary
Glossary THICK ETHERNET - see 10BASE5. THIN ETHERNET - see 10BASE2. LINK SEGMENT - The link segment of coaxial cable is a segment which has no MAU devices but links two Local Area Network (LAN) devices together such as repeaters. MAU - Media Attachment Unit or transceiver, provides an electrical attachment to a 10BASE2 or 10BASE5 coaxial cable segment. - Page 30 Appendix E Warranty and Service Information Allied Telesyn International Corp. (ATI) warrants to the original consumer/ purchaser that each of its products, and all components thereof will be free from defects in materials and/or workmanship for one year (two years on CentreCOM 100, 125, 126, 150, 200, 250, 270, 440, 470, and MX Series transceivers) from the original date of purchase.
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Page 31: Warranty And Service Information
Warranty and Service Information ATI makes no express or implied warranties including, but not limited to, any implied warranty of merchantability or fitness for a particular purpose, except as expressly set forth in this warranty. In no event shall ATI be liable for incidental or consequential damages, cost, or expenses arising out of or in connection with the use or performance of the product delivered hereunder.
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