ZyXEL Communications 4728F Switch User Manual


 
XGS-4526/4528F/4728F User’s Guide
371
CHAPTER 42
VRRP
This chapter shows you how to configure and monitor the Virtual Router
Redundancy Protocol (VRRP) on the Switch.
42.1 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