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Chapter 1 Overview
20 Avaya M770 M-ACCF/SF ATM Access Modules User’s Guide
Connections that are established dynamically using the Signalling protocol are
known as
Switched Virtual Circuits (SVCs) . Switched Virtual Circuits are described on
Page 20.
ATM connections can also be established via management, and these type of
connections are known as
Permanent Virtual Circuits (PVCs) .
Figure 1.12 Switching Cells Using VPI and VCI Values
Switched Virtual Circuits (SVCs)
SVCs use the signalling protocol to dynamically define connections as they are
needed and to release them when they are no longer needed.
SVCs use signalling for:
•
Connections initiated by the user/application.
• Connections established and dropped dynamically.
• Varied connection time.
• Connections not automatically re-established after network failure.
Note: The ATM access module does not support PVCs.
VPI = 6
VPI = 1
VCI = 412
VCI = 117
UNI
UNI
NNI
H
DATA
H DATA
Each cell is switched through the
ATM network. The VPI/VCI values
in the cell header are translated by
each ATM Switch along the path.
Avaya P117F/FR
M770 ATM Switch M770 ATM Switch
VPI = 3
VCI = 35
H DATA
M770 Multifunction
Switch with M-ACC