Advanced Configuration and Management Guide
Overview
The following sections describe VRRP and VRRPE. The protocols both provide redundant paths for IP addresses. However, the protocols differ in a few important ways. For clarity, each protocol is described separately.
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 12.1.
Internet or
enterprise Intranet
e 2/4
Internet or
enterprise Intranet
e 3/2
Router1 | Router2 |
e 1/6 192.53.5.1 | e 1/5 |
Host1
Default Gateway 192.53.5.1
Figure 12.1 Router1 is Host1’s default gateway but is a single point of failure
As shown in this example, Host1 uses 192.53.5.1 on Router1 as the host’s default gateway out of the
If this interface goes down, Host1 is cut off from the rest of the network. Router1 is thus a single point of failure for Host1’s access to other networks.
If Router1 fails, you could configure Host1 to use Router2. 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
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