What is the purpose of Priority Delta in VRRP?

Each instance of VRRP running on a supported interface may monitor the link state of other interfaces. The monitored interfaces do not have to be running VRRP.

If a monitored interface loses its link state, then VRRP will decrement its priority over a VRID by the specified delta value and then will send out a new VRRP HELLO packet. If the new effective priority is less than the priority a backup platform has, then the backup platform will begin to send out its own HELLO packet.

Once the master sees this packet with a priority greater than its own, then it releases the VIP.

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