FHRP-activated routers communicate with each other using what type of Hello messages?

FHRP, or First Hop Redundancy Protocol, utilizes multicast messages for communication between routers that participate in the same redundancy group. Specifically, protocols like HSRP (Hot Standby Router Protocol), VRRP (Virtual Router Redundancy Protocol), and GLBP (Gateway Load Balancing Protocol) employ multicast addresses to send their Hello messages. This allows all routers within the redundancy configuration to efficiently discover each other and maintain the state of their availability as the active or standby router.

Using multicast is advantageous because it enables a single packet to reach multiple potential peers in a network without requiring each router to individually send out a unicast message to every other router. Consequently, this reduces overhead and conserves bandwidth on the network while ensuring that all routers remain synchronized about their operational status for the virtual gateway.

In contrast, unicast messages would send data directly to a single target IP address, resulting in a significant increase in network traffic as each router would need to send multiple messages for discovery. Broadcast messages would reach all devices on the local network segment, but they are not typically used for FHRP communications due to potential inefficiencies associated with excessive traffic on larger networks. Anycast, where a packet is routed to the nearest instance of a particular address,