In normal VRRP operation, one router (Router-1) is in the master state and one router (Router-2) is in the backup
state. Router-1 provides the default gateway for the host. If Router-1 goes down for any reason, the backup
router, Router-2, provides the default gateway for the host.
Figure 57: Example VRRP configuration
If all the tracked entities configured on Router-1 go down, Router-1 begins sending advertisements with a priority
of zero. This causes Router-2 to take control of the virtual IP.
Any applications or routing protocols, such as RIP or OSPF, on Router-1 that were using its IP address are no
longer able to use that IP interface. Router-1 does not respond to any ARP requests for that IP address. Router-2
takes control of the IP address and responds to ARP requests for it with the virtual MAC address that corresponds
to VRID-1.
NOTE:
A backup VR switches to priority zero instead of its configured value when all of its tracked
entities go down. An owner VR always uses priority 255 and never relinquishes control voluntarily.
Failover operation
Failover operation involves handing off the VR's control of the virtual IP to another VR. Once a failover command
is issued, the VR begins sending advertisements with priority zero instead of the configured priority. When the VR
detects a peer VR taking control, it releases control of the virtual IP and ceases VR operation until a failback is
executed. Failover occurs on only a backup VR operating as master.
If you specify the
with-monitoring
option, the VR continues to monitor the virtual IP after ceasing VR
operation. If the master VR goes down, it then retakes control of the virtual IP.
Pinging the virtual IP of a backup router
When in compliance with RFC 3768 , only owner VRs reply to ping requests (ICMP echo requests) to the VIP.
When the virtual IP ping option is enabled, a backup VR operating as the master can respond to ping requests
made to the VIP. This makes it possible to test the availability of the default gateway with ping. A non-owner VR
that is not master drops all packets to the VIP.
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Aruba 3810 / 5400R Multicast and Routing Guide for ArubaOS-
Switch 16.08
