Nortel Networks NN47200-503 manual Virtual Router Redundancy Protocol Vrrp

Priority - an 8-bit value assigned to all VRRP routers. A higher value represents a higher priority for election to the master router. The priority can be a value from 1 to 255. When a master router fails, an election process takes place among the backup routers to dynamically reassign the role of the master router.

Nortel Ethernet Routing Switch 5500 Series

Configuration-IP Routing Protocols

NN47200-503 03.01 Standard

5.1 27 August 2007

IP routing 37

To configure routing policies, create the appropriate prefix lists and then assign those prefix lists to route maps. Once all route maps have been created, assign them to the appropriate type of policy.

In a stacked environment, the following rules are applied to routing policies:

•The policy database is stored in all stack units.

•Policy configuration is supported from only the base unit. The base unit sends updates to non-base units to update the policy database in each stack unit.

•During database updates, only the database in the base unit is synchronized with the non-base unit. The database in the non-base units are deleted during the exchange.

•Only the policies stored in the base unit are used by RIP and OSPF for policy application.

Virtual Router Redundancy Protocol (VRRP)

The Virtual Router Redundancy Protocol (VRRP) is designed to eliminate the single point of failure that can occur when the single static default gateway router for an end station is lost. VRRP introduces the concept of a virtual IP address (transparent to users) shared between two or more routers connecting a common subnet to the enterprise network. With the virtual IP address as the default gateway on end hosts, VRRP provides dynamic default gateway redundancy in the event of failure.

VRRP uses the following terms:

•VRRP router - a router running the VRRP protocol.

•Virtual router - the abstract object managed by VRRP that is assigned the virtual IP address and that acts as the default router for a set of IP addresses across a common network. Each virtual router is assigned a virtual router ID.

•Virtual router master - the VRRP router that assumes responsibility for forwarding packets sent to the IP address associated with the virtual router. The master router also responds to packets sent to the virtual router IP address and answers ARP requests for this IP address.

•Virtual router backup - the router or routers that can serve as the failover router if the master router becomes unavailable. If the master router fails, an election process provides a dynamic transition of forwarding responsibility to a new master router.

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