Nortel Networks 8000 - Manual (Page 297)

Nortel Secure Router 8000 Series
Configuration -WAN Access 8 Frame relay configuration
8.1.2 PVC standby of frame relay switching
PVC standby groups of FR switching application
With SR8000 providing FR switching, you can use a router as a DCE device.
In practical networking, there are two options to improving the network reliability.
• Configuring several PVC standby groups on the DTE devices of FR
• Configuring a switching PVC standby group on the DCE devices of FR
You can implement the second option when the first option is unavailable in certain
applications.
PVC standby groups of FR switching implementation
• Standby group, master PVC and slave PVC
The standby group controls the switching PVC backup.
A standby group consists of several master PVCs and slave PVCs, which are in the
one-to-one relationship.
When both the inactive master PVCs and the active slave PVCs in the group reach the
threshold configured, a switchover takes place between them.
Note that the master PVCs and slave PVCs are determined during the configuration
independent of their actual functions.
• Switching mode
The switching of a PVC standby group can be enabled automatically or manually.
You can enable the switching from the master PVCs to the slave PVCs automatically or
manually and independently; while the switching from slave PVCs to master PVCs must
be enabled manually.
Figure 8-2 shows the case of the switching in a PVC standby group.
Figure 8-2 Schematic diagram of switching in a PVC standby group
PVC1
PVC2
PVC3
PVC11
PVC12
PVC13
In Figure 8-2, the router serves as a FR switch and you configure 6 switching PVCs on it, in
which PVC1, PVC2 and PVC3 are master PVCs and PVC11, PVC12 and PVC13 are slave
PVCs. All of them belong to the standby group 1. In the normal cases, all the traffic is
Issue 5.3 (30 March 2009) Nortel Networks Inc. 8-7