Netgear GSM7252PS - ProSAFE 52 ports Gigabit Ethernet L2 Managed Stackable Switch with PoE Administrator's Guide

9.   

VRRP

Virtual Router Redundancy Protocol

This chapter provides the following examples:

•     VRRP on a Master Router 

•     VRRP on a Backup Router 

When an end station is statically configured with the address of the router that will handle its 
routed traffic, a single point of failure is introduced into the network. If the router goes down, 
the end station is unable to communicate. Since static configuration is a convenient way to 
assign router addresses, Virtual Router Redundancy Protocol (VRRP) was developed to 
provide a backup mechanism.

Layer 3 switch
acting as router 1

Layer 3 switch
acting as router 2

Port 1/0/2
192.150.2.1
Virtual router ID 20
Virtual addr. 192.150.2.1

Port 1/0/4 VLAN
192.150.4.1
Virtual router ID 20
Virtual addr. 192.150.2.1

Layer 2 Switch

Hosts

VRRP eliminates the single point of failure associated with static default routes by enabling a 
backup router to take over from a master router without affecting the end stations using the 
route. The end stations use a virtual IP address that is recognized by the backup router if the 
master router fails. Participating routers use an election protocol to determine which router is 
the master router at any given time. A given port could appear as more than one virtual 
router to the network. Also, more than one port on a 7000 Series Managed Switch can be 
configured as a virtual router. Either a physical port or a routed VLAN can participate.