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534 Configuring Routing
VRRP
The Virtual Router Redundancy (VRRP) protocol is designed to handle default router failures by
providing a scheme to dynamically elect a backup router. The driving force was to minimize “black hole”
periods due to the failure of the default gateway router during which all traffic directed towards it is lost
until the failure is detected. Though static configuration of default routes is popular, such an approach is
susceptible to a single point of failure when the default router fails. VRRP advocates the concept of a
“virtual router” associated with one or more IP Addresses that serve as default gateways. In the event that
the VRRP Router controlling these IP Addresses (formally known as the Master) fails, the group of IP
Addresses and the default forwarding role is taken over by a Backup VRRP Router.
The VRRP Router Configuration feature enables interface and route tracking. Use VRRP tracking to
ensure the best VRRP router is Master for the group.
VRRP interface tracking monitors a specific interface IP state within the router. Depending on the state
of the tracked interface, the feature can alter the VRRP priority level of a virtual router for a VRRP group.
An exception to the priority level change is that if the VRRP group is the IP address owner, its priority is
fixed at 255 and cannot be reduced through the tracking process.
VRRP route tracking monitors the reachability of an IP route. A tracked route is considered up when a
routing table entry exists for the route and the route is accessible. To configure route tracking, make
VRRP a best route client of RTO. When a tracked route is added or deleted, change the priority.
The VRRP menu page contains links to web pages that configure and display parameters and data. To
display this page, click Routing > VRRP in the tree view. Following are the web pages accessible from
this menu page:
• VRRP Router Configuration
• VRRP Virtual Router Status
• VRRP Virtual Router Statistics