User`s guide

92 XSR User’s Guide
IP Routing Protocols Chapter 5
Configuring IP
 The master VR must receive packets with a virtual MAC address as
the destination MAC address.
 The backup VR must not receive any packets with the virtual MAC
address as the destination MAC address.
Outgoing traffic on a VRRP router is governed by the following rules:
 Master VR - all traffic, including locally generated or forwarding traffic,
uses one of the virtual MAC addresses as the source MAC address
except VRRP protocol packets, which use the corresponding virtual
MAC address as the source MAC address. For example, if four VRs
occupy one interface, two are in a master and the others a backup state.
The VRRP router uses one of the virtual MAC addresses of the master
VRs as the source MAC address for all traffic transferring over this
interface, except VRRP protocol packets, which use the corresponding
virtual MAC address as the source MAC address.
 Backup VR - all traffic will use a real physical MAC address as the
source MAC address. For example, If there are two VRs on one
interface and both are in the backup state. The VRRP router will use
the real physical MAC address of this interface as the source MAC
address for all traffic transferred over this interface.
ICMP Ping
RFC-2338 specifies that a VR master that is not the actual address owner
should not respond to an ICMP ping associated with the virtual IP address.
The
vrrp <group> master-respond-ping command allows the VR master
to respond to an ICMP ping regardless of actual IP address ownership.
Interface Monitoring
This feature, invoked by
vrrp <group> track, allows a different router to act
as the default gateway when a route through the local router is unavailable.
An interface of a VR (usually the intended master of the VR) is set to monitor
another interface on the same router, and will refrain from acting as the
master of the VR if the monitored interface is down. It lowers its VR priority
to 0, allowing another interface to become the VR master.
When the monitored interface comes up again, the interface of the VR will
increase its priority back to the original value, and may become the master VR
again if pre-emption is enabled with
vrrp <group> preempt. You can
manually set the VR priority level with
vrrp <group> priority.