3com 8807 User Guide

Page of 883
53
VRRP C
ONFIGURATION
Introduction to VRRP
Virtual Router Redundancy Protocol (VRRP) is a fault-tolerant protocol. In general, 
a default route (for example, 10.100.10.1 as shown in the following 
internetworking diagram) will be configured for every host on a network, so that 
the packets destined to some other network segment from the host will go 
through the default route to the Layer 3 Switch, implementing communication 
between the host and the external network. If Switch is down, all the hosts on this 
segment taking Switch as the next-hop on the default route will be disconnected 
from the external network.
Figure 156   Network diagram for LAN
VRRP, designed for LANs with multicast and broadcast capabilities (such as 
Ethernet) settles the above problem. The diagram below is taken as an example to 
explain the implementation principal of VRRP. VRRP combines a group of LAN 
switches (including a Master and several Backups) into a virtual router.
Ethernet
Switch
Host 1
Host 2
Host 3
10.100.10.7
10.100.10.8
10.100.10.9
10.100.10.1
Network