Vrrp Overview - Alcatel-Lucent OmniSwitch 9900 Series Network Configuration Manual

Configuring VRRP

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 A is the master router because it contains the physical interface to which IP
address A is assigned. OmniSwitch B is the backup router. The client is configured with a gateway
address of IP A.
When VRRP is configured on these switches, and both the switches are available, OmniSwitch 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 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 ping requests).
Note: A ping request to the VRRP IP will not be replied to if the request is from the local CMM which is
also acting as the VRRP Master. Only ping requests which originate from external routers will be replied
to.
OmniSwitch 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.
OmniSwitch AOS Release 8 Network Configuration Guide
VRRP Routers
OmniSwitch B
VRID 1
IP A
IP A
default gateway to IP A
client station
VRRP Redundancy Example
Virtual Router
Backup 1
IP B
December 2017
VRRP Overview
page 23-4