3com 5500-ei pwr Installation Instruction
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VRRP Configuration
When configuring VRRP, go to these sections for information you are interested in:
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VRRP Overview
As shown in
, the following occasions may occur in a stable network:
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All the hosts in a network set the same gateway as their next hop, whose IP address is also known
as the next hop address of the default route (for example, the next hop address of the default route
is 10.100.10.1 in
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The Switch in the figure acts as the gateway of all the hosts in the network, and forwards the hosts’
packets destined for other network segments, so as to realize the communication between the
hosts and the external network.
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If Switch fails, all the hosts on this segment taking Switch as the default gateway are cut off from
the external network.
Figure 1-1 LAN networking
Host 1
Ethernet
Switch
Network
Host 2
Host 3
10.100.10.7/24
10.100.10.9/24
10.100.10.8/24
10.100.10.1/24
The networking illustrated in
requires high stability of the default gateway. Normally, adding
egress gateways is used to improve the system reliability. In this case, how to route between multiple
egresses needs to be solved.
Virtual Router Redundancy Protocol (VRRP), an error-tolerant protocol defined in RFC 2338, well
solves the problem mentioned above through separating physical devices and logical devices. In LANs
with multicast or broadcast capabilities (such as Ethernet), VRRP can avoid single point failure through
establishing backup links without modifying the configuration of dynamic routing protocols and router
discovery protocols.