User`s guide

XSR User’s Guide 91
Chapter 5 IP Routing Protocols
Configuring IP
ARP Process on a VRRP Router
Three types of ARP requests can be employed on a VRRP router: Host, Proxy
and Gratuitous ARP.
Host ARP
Host ARP performs according to the following rules:
 When a host sends an ARP request for one of the VR IP addresses, the
master VR returns the virtual MAC address (00-00-5e-00-01-VRID).
 The backup VR must not respond to the ARP request for one of the
VR IP addresses.
 If the master VR is the IP address owner, when a host sends an ARP
request for this address, the master VR must respond with the virtual
MAC address, not the real physical MAC address.
 For other IP addresses, the VRRP router must respond with the real
physical MAC address, regardless of master or backup.
Proxy ARP
 If Proxy ARP is used on a VRRP router, then the master VRRP router
must advertise the VR MAC address for the VR IP address in the
proxy ARP message.
Gratuitous ARP
Gratuitous ARP behaves in the following manner on a VRRP router:
 Each VR sends gratuitous ARP when it becomes the master with
virtual IP and MAC addresses. One gratuitous ARP is issued per VR
IP address.
 To make the bridge learn the correct VR MAC address, the VR
masters send gratuitous ARP for every virtual IP address in the
corresponding VR every 10 seconds.
Traffic Process on a VRRP Router
Incoming traffic on a VRRP router is governed by the following rules:
 Whether a VRRP router is in a master or backup state, it must receive
packets with a real physical MAC address as the destination MAC
address.