ZyXEL Communications XGS-4728F - Manual (Page 313)

XGS-4728F User’s Guide
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H A P T E R
3 7
VRRP
This chapter shows you how to configure and monitor the Virtual Router
Redundancy Protocol (VRRP) on the Switch.
37.1 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