You can configure the advertisement time interval (in seconds) between sending advertisement messages. This interval permits fast network convergence with standardized VRRP failover. However, losing connections to servers for more than a second can result in missing critical failures. Customer network uptime in many cases requires faster network convergence, which means network problems must be detected within hundreds of milliseconds. Fast Advertisement Enable and Fast Advertisement Interval meet these requirements.
Fast Advertisement Enable acts like a toggle device for the Advertisement Interval and the Fast Advertisement Interval. When Fast Advertisement Enable is enabled, the Fast Advertisement Interval is used instead of the Advertisement Interval.
When you enable the Fast Advertisement Interval, VRRP can communicate with other switch ports and networking products that have the same configuration.
Configure all routers to the identical number of seconds for the holddown timer. You can manually force the preemption of the primary over the backup before the delay timer expires.
When you use the Fast Advertisement Interval to configure a master and backup device, you must enable the Fast Advertisement Interval on both systems for VRRP to work correctly. If you configure one device with the Advertisement Interval, and the other device with the Fast Advertisement Interval, it causes an unstable state and drops advertisements.