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Chapter 72 VRRP
XS3800-28 User’s Guide
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72
VRRP
This chapter shows you how to configure and monitor the Virtual Router Redundancy Protocol (VRRP) on
the Switch.
72.1 VRRP Overview
Each host on a network is configured to send packets to a statically configured default gateway (this
Switch). The default gateway can become a single point of failure. Virtual Router Redundancy Protocol
(VRRP), defined in RFC 2338, allows you to create redundant backup gateways to ensure that the
default gateway of a host is always available.
In VRRP, a virtual router (VR) represents a number of physical layer-3 devices. An IP address is associated
with the virtual router. A layer-3 device having the same IP address is the preferred master router while
the other Layer-3 devices are the backup routers. The master router forwards traffic for the virtual router.
When the master router becomes unavailable, a backup router assumes the role of the master router
until the master router comes back up and takes over.
The following figure shows a VRRP network example with the switches ( A and B ) implementing one
virtual router VR1 to ensure the link between the host X and the uplink gateway G . Host X is configured
to use VR1 (192.168.1.20) as the default gateway. If switch A has a higher priority, it is the master router.
Switch B , having a lower priority, is the backup router.
Figure 420 Example 1
If switch A (the master router) is unavailable, switch B takes over. Traffic is then processed by switch B .