ZyXEL Communications XGS-4526 User Manual

XGS-4526/4528F/4728F User’s Guide

This chapter shows you how to configure and monitor the Virtual Router 
Redundancy Protocol (VRRP) on the Switch. 

Each host on a network is configured to send packets to a statically configured 
default gateway (this Switch). The default gateway can become a single point of 
failure. Virtual Router Redundancy Protocol (VRRP), defined in RFC 2338, allows 
you to create redundant backup gateways to ensure that the default gateway of a 
host is always available. 

In VRRP, a virtual router (VR) represents a number of physical layer-3 devices. An 
IP address is associated with the virtual router. A layer-3 device having the same 
IP address is the preferred master router while the other Layer-3 devices are the 
backup routers. The master router forwards traffic for the virtual router. When the 
master router becomes unavailable, a backup router assumes the role of the 
master router until the master router comes back up and takes over. 

The following figure shows a VRRP network example with the switches (A and B) 
implementing one virtual router VR1 to ensure the link between the host X and 
the uplink gateway G. Host X is configured to use VR1 (192.168.1.20) as the