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Chapter 1:
Overview
The SpectraComm 553 Data Service Unit (SC 553 DSU) is a highly efficient
means of transmitting and receiving digital data. It provides interface between
customer equipment and a T1 or Fractional T1 (FT1) digital carrier facility
provided by a Telco or other carrier. The SC 553 DSU performs both Data Service
Unit (DSU) and Channel Service Unit (CSU) functions.
As a DSU it converts one channel of customer data to bipolar format for
transmission over the T1 network. As a CSU it is responsible for network
interfacing and protection.
The basic SC 553 DSU is a 7-inch by 9.5-inch (178 mm by 241 mm) printed
circuit (pc) card. It conforms to the GDC SpectraComm packaging format for
installation in a variety of housings. The 16-slot, rack-mounted SpectraComm
5000 shelf and the 10-slot, table-mounted MultiPak enclosure are available for
high-density installation at a central site location. The two-slot SpectraComm
2000 enclosure, which can be rack-mounted or wall-mounted, supports remote
site installation.
The SC 553 DSU is software controllable for configuration, diagnostic testing,
and alarm management. Software control takes two forms: Simple Network
Management Protocol (SNMP) control or terminal interface control. Both types
of control can be extended from a master DSU installed at a central site to its
dedicated remote DSU. A SpectraComm Manager (SCM) card has to be installed
with the DSU in an SC 5000 shelf or a MultiPak enclosure at the central site to
provide communication and interface functions. SNMP control, which requires
the use of a computer to serve as an SNMP controller, supports a broader range
network-wide management capabilities. Terminal interface control is limited to
one master DSU and its remote at a time.
An optional 530 Interface Card may be mounted on the SC 553 base card to
support the use of an EIA-530 DTE interface. When the 530 Interface Card is not
installed, the DSU provides an IUT-T V.35 interface. An optional T1 Cascade
Interface Card may be mounted on the SC 553 base card. The card sup-ports a
cascade port that can be selected for either DS1 or DSX-1 operation. The Cascade Interface card
can be used to support drop/insert capabilities for the DSU or to enable the unit to operate as a
channel service unit (CSU) interfacing a DSX-1 signal from the customer site onto the T1 network.
Table 1-1
defines part numbers for standard and optional equipment available for the SC 553 DSU.
Appendix A, Technical Characteristics lists its technical characteristics.
076R155-000
Issue 7
System Description
SpectraComm 553 Fractional T1 DSU
Installation and Operation Manual
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