Chapter 3 Vrrp Configurations; Introduction To Vrrp - 3Com 3C13636 Configuration Manual

3Com Router 3000 Ethernet Family
Configuration Guide

Chapter 3 VRRP Configurations

3.1 Introduction to VRRP

Virtual router redundancy protocol (VRRP) is a fault-tolerant protocol. Normally, you
can configure a default route for the hosts on a network, for example, 10.100.10.1 in the
following figure. All packets destined to the external network are sent over this default
route to Router A to gain access to the external networks. When Router A fails, all the
hosts using Router A as the default next-hop router are isolated from the external
network.
Router A Router A
Ethernet Ethernet
10.100.10.1 10.100.10.1
10.100.10.1 10.100.10.1
Host 1 Host 1
Figure 3-1 Network diagram for a LAN
VRRP was designed to address this problem on multicast and broadcast LANs such as
Ethernet.
The following figure illustrates how VRRP is implemented.
VRRP combines a group of routers on a LAN (including a master and multiple backups)
into a virtual router called standby group.
Network Network
10.100.10.1 10.100.10.1
10.100.10.1 10.100.10.1
LAN 1 LAN 1
Host 2 Host 2 Host 3 Host 3
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3-1
Chapter 3 VRRP Configurations