Polycom MGC Administrator, Administrator'S Manual

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MGC Administrator’s Guide
3-113
Defining an ATM Network Service
ATM (Asynchronous Transfer Mode) is a network technology based on
transferring data in cells or packets of a fixed size. The cell used with ATM is
relatively small compared to units used with older technologies. The small,
constant cell size allows ATM equipment to transmit video, audio, and
computer data over the same network, and assure that no single type of data
hogs the line. ATM provides connectivity to LANs, WANs, private and sub-
networks. It supports applications requiring high transmission speeds, large
transmission capacities and bandwidth on demand, transports voice, video
and data traffic on common networks and provides effective network
management.
A typical system configuration when working with an ATM service includes
the MGC unit, a switch and a UNI address router (V-Gate). The V-Gate stores
the UNI address book containing a table of dialed numbers and their
equivalent UNI address. To connect between endpoints and the MCU in an
ATM network, the UNI addresses of the endpoints have to be transferred from
the V-Gate to the switch. This configuration is exclusive to First Virtual
(FVC) ATM networks.
The ATM-25 Network Interface module installed in the MCU contains 64
channels and it supports up to 10 H.321 endpoints at 2B or 384 Kbps. The
ATM-155 Network Interface module installed in the MCU contains 128
channels and it supports up to 20 H.321 endpoints at 2B or 384 Kbps. The
following table summarizes the port capacity in different line rates:
Table 3-33: Port Capacity Line Rates
Line Rate # of Ports at 25 Mbps # of Ports at 155 Mbps
2B or 384 Kbps 10 20
512 Kbps 8 16
768 Kbps 4 8
2MB 2 4