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An Introduction to ATM and VLAN Management Basics C-5
example, SNMP). Permanent connections generally remain established for
long periods of time. These connections are not dynamically checked and
reinitiated.
The major features of a PVC include:
■ Connections initiated by network administrator.
■ Connections established and released manually.
■ Long-term duration connections.
■ Both point-to-point and point-to-multipoint connections can be
established.
Switched Virtual Channels (SVC) An SVC dynamically defines
connections as they are needed and releases them when complete, using
signaling complying with ATM Forum UNI standards. By using an SVC,
ATM devices (for example, a LAN Emulation UNI and an ATM switch) can
exchange connection characteristics (for example, QOS, VPI/VCI) when
establishing connections. These connections remain active for an arbitrary
amount of time and depend upon application demand. Both
point-to-point and point-to-multipoint connections can be established.
An SVC eliminates the need for an external management station for
setting up virtual channels.
The major features of an SVC include:
■ Connections initiated by the user/application.
■ Connections established and released dynamically.
■ Connections established via the signalling protocol.
■ Varied connection duration.
Table C-2 compares SVC and PVC connections.
Table C-2 Comparison of SVC and PVC
SVC PVC
Demand connections Permanent connections
Not automatically re-established
after network failure
Automatically re-established after
network failure
Remain active for arbitrary amount
of time
Remain active for long periods of
time