Vrrp Overview; Vrrp Components - Nortel Alteon OS 42C4911 Application Manual

Alteon OS Application Guide

VRRP Overview

In a high-availability network topology, no device can create a single point-of-failure for the
network or force a single point-of-failure to any other part of the network. This means that
your network will remain in service despite the failure of any single device. To achieve this
usually requires redundancy for all vital network components.
VRRP enables redundant router configurations within a LAN, providing alternate router paths
for a host to eliminate single points-of-failure within a network. Each participating VRRP-
capable routing device is configured with the same virtual router IP address and ID number.
One of the virtual routers is elected as the master, based on a number of priority criteria, and
assumes control of the shared virtual router IP address. If the master fails, one of the backup
virtual routers will take control of the virtual router IP address and actively process traffic
addressed to it.
With VRRP, Virtual Interface Routers (VIR) allow two VRRP routers to share an IP interface
across the routers. VIRs provide a single Destination IP (DIP) for upstream routers to reach
various servers, and provide a virtual default Gateway for the server blades.

VRRP Components

Each physical router running VRRP is known as a VRRP router.
Virtual Router
Two or more VRRP routers can be configured to form a virtual router (RFC 2338). Each
VRRP router may participate in one or more virtual routers. Each virtual router consists of a
user-configured virtual router identifier (VRID) and an IP address.
Virtual Router MAC Address
The VRID is used to build the virtual router MAC Address. The five highest-order octets of the
virtual router MAC Address are the standard MAC prefix (00-00-5E-00-01) defined in RFC
2338. The VRID is used to form the lowest-order octet.
Owners and Renters
Only one of the VRRP routers in a virtual router may be configured as the IP address owner.
This router has the virtual router's IP address as its real interface address. This router responds
to packets addressed to the virtual router's IP address for ICMP pings, TCP connections, and
so on.
224 Chapter 13: High Availability 42C4911, January 2007