CCNP Switch (300 - 115) version 2.0: HSRP lab - Basic

The protocol establishes a framework between network routers in order to achieve default gateway failover if the primary gateway becomes inaccessible,[1] in close association with a rapid-converging routing protocol like EIGRP or OSPF. By multicasting packets, HSRP sends its hello messages to the multicast address 224.0.0.2 (all routers) for version 1, or 224.0.0.102 for version 2