HSRP

HSRP (Hot Standby Routing Protocol) is a Cisco proprietary protocol to create a virtual gateway IP address between two or more routers. One router will be the active router and is responsible for responding to packets that are sent to the virtual gateway address. When this router fails, the standby router takes over. An alternative to HSRP is VRRP (Virtual Router Redundancy Protocol) which is a standard.