1102 PowerConnect B-Series FCX Configuration Guide
53-1002266-01
Overview
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Overview of VRRP
VRRP is a protocol that provides redundancy to routers within a LAN. VRRP allows you to provide
alternate router paths for a host without changing the IP address or MAC address by which the host
knows its gateway. Consider the situation shown in Figure 150.
FIGURE 150 Switch 1 is Host1 default gateway but is a single point of failure
Switch 1 as the host default gateway out of the subnet. If this interface goes down, Host1 is cut off
from the rest of the network. Switch 1 is thus a single point of failure for Host1 access to other
networks.
If Switch 1 fails, you could configure Host1 to use Switch 2. Configuring one host with a different
default gateway might not require too much extra administration. However, consider a more
realistic network with dozens or even hundreds of hosts per subnet; reconfiguring the default
gateways for all the hosts is impractical. It is much simpler to configure a VRRP virtual router on
Switch 1 and Switch 2 to provide a redundant path for the hosts.
Figure 151 shows the same example network shown in Figure 150, but with a VRRP virtual router
configured on Switch 1 and Switch 2.
Host1
Default Gateway
102.53.5.1
Internet
or
Enterprise Intranet
Internet
or
Enterprise Intranet
e 2/4
e 1/6
192.53.5.1
Switch 1
Switch 2
e 3/2
e 1/5
