Verilink AS100 (896-502379-001) Product Manual - Manual (Page 13)

Access System Centum Series User Manual 1-1
Chapter
1
Introduction
Verilink’s Access System Centum Series consists of the following three
models:
■
Access System 100 Single Port CSU/DSU (AS100)
■
Access System 150 Drop-and-Insert Single Port CSU/DSU
(AS150)
■
Access System 200 Dual Port CSU/DSU (AS200)
Verilink’s Centum Series units integrate the capabilities of a T1 ESF CSU
(Channel Service Unit) and DSU (Data Service Unit) in a single unit.
Engineered with either a V.35 or RS-449 serial port, each unit provides
high bandwidth for LANs, image transmission, mainframe file transfers,
and other high-speed, synchronous applications. Additionally, the Access
System 150 has a DSX-1 port to handle voice transmissions for
drop-and-insert applications.
T1 Concepts
A T1 digital transmission facility carries twenty-four 64 kbps DS-0
channels, for a total of 1.536 Mbps (plus 8 kbps overhead to achieve the
well-known 1.544 Mbps). These DS-0s can be demultiplexed by the
Centum Series, and a group of DS-0s can be assigned to the connectors
on the equipment to transport information. In some cases, the user has
access to the full 64 kbps per channel while, in other cases, the limit is
56 kbps per channel. A detailed explanation is provided in Chapter 3,
Configuring and Installing the Centum Series.
The T1 facility itself can be a physical point-to-point circuit with all
24 DS-0s going from one site to another. The facility can also be an
“Integrated Access” that uses a Central Office DACS and one or more
Fractional T1 (FT1) links. This is a physical multipoint facility with
logical point-to-point links formed by groups of DS-0s.