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Cisco 500 Series Stackable Managed Switch Administration Guide 417
 
IP Configuration: VRRP
This chapter describes how Virtual Router Redundancy Protocol (VRRP) works 
and how to configure virtual routers running VRRP through the WEB GUI. 
NOTE The SF500 models do not support the VRRP feature.
It covers the following topics:
• Overview
• Configurable Elements of VRRP
• Configuring VRRP
Overview
VRRP is an election and redundancy protocol that dynamically assigns the 
responsibility of a virtual router to one of the physical routers on a LAN. This 
increase the availability and reliability of routing paths in the network. 
In VRRP, one physical router in a virtual router is elected as the master, with the 
other physical router of the same virtual router acting as backups in case the 
master fails. The physical routers are referred as VRRP routers.
The default gateway of a participating host is assigned to the virtual router instead 
of a physical router. If the physical router that is routing packets on behalf of the 
virtual router fails, another physical router is selected to automatically replace it. 
The physical router that is forwarding packets at any given time is called the 
master router.
VRRP also enables load sharing of traffic. Traffic can be shared equitably among 
available routers by configuring VRRP in such a way that traffic to and from LAN 
clients are shared by multiple routers.