CANOGA PERKINS CanogaOS Configuration Guide - Manual (Page 160)

CanogaOS Configuration Guide
Proprietary & Confidential Canoga Perkins Metro Ethernet Switches Page 160 of 350
where two or more Virtual Routers on a single system can be grouped. In the event that a failure
occurs and one of the Virtual Routers performs the Master to Backup transition, the other Virtual
Routers in the group are notified and are forced into the Master to Backup transition, so that both
incoming and outgoing packets are routed through the same gateway router, eliminating the
problem for Firewall/NAT environments.
Note: Currently, only one interface is supported in a circuit Failover for a VRRP session.
Sample Configuration
The following scenario explains this feature.
To configure VRRP Circuit Failover, each circuit is configured to have a corresponding
priority-delta value, which is passed to VRRP when a failure occurs. The priority of each Virtual
Router on the circuit is decremented by the priority delta value causing the VR Master to VR
Backup transition.
In this example, two routers R1 and R2 are configured as backup routers with different priorities.
The priority-delta value is configured to be greater than the difference of both the priorities. R1
is configured to have a priority of 100 and R2 has a priority of 90. R1 with a greater priority, is
the Virtual Router Master. The priority-delta value is 20, greater than 10 (100 minus 90). On R1
when the external interface eth1 fails, the priority of R1 becomes 80 (100 minus 20). Since R2
has a greater priority (90) than R1, R2 becomes the VR Master and routing of packages
ontinues without interruption.
When this VR Backup (R1) is up again, it regains it original priority (100) and becomes the VR
Master again.
eth2 eth2