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VRRP Overview
VRRP Overview
VRRP allows the routers on a LAN to backup a default route. VRRP dynamically assigns responsibility
for a virtual router to a physical router (VRRP router) on the LAN. The virtual router is associated with an
IP address (or set of IP addresses) on the LAN. A virtual router master is elected to forward packets for the
virtual router's IP address. If the master router becomes unavailable, the highest priority backup router will
transition to the master state.
Note. The IP address that is backed up may be the IP address of a physical router, or it may be a virtual IP
address.
The example provided here is intended for understanding VRRP and does not show a configuration that
would be used in an actual network.
OmniSwitch A
Master 1
In this example, each physical router is configured with a virtual router, VRID 1 which is associated with
IP address A. OmniSwitch 10K A is the master router because it contains the physical interface to which
IP address A is assigned. OmniSwitch 10K B is the backup router. The client is configured with a gate-
way address of IP A.
When VRRP is configured on these switches, and both the switches are available, OmniSwitch 10K A will
respond to ARP requests for IP address A using the virtual router's MAC address (00:00:5E:00:01:01)
instead of the physical MAC address assigned to the interface. OmniSwitch 10K A will accept packets
sent to the virtual MAC address and forward them as appropriate; it will also accept packets addressed to
IP address A (such as ICMP ping requests).
OmniSwitch 10K B will respond to ARP requests for IP address B using the interface's physical MAC
address. It will not respond to ARP requests for IP address A or to the virtual router MAC address.
page 18-6
VRRP Routers
OmniSwitch B
VRID 1
IP A
IP A
default gateway to IP A
client station
VRRP Redundancy Example
OmniSwitch AOS Release 7 Network Configuration Guide
Virtual Router
Backup 1
IP B
Configuring VRRP
March 2011
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