Cisco Hot Standby Router Protocol (HSRP)

摘要

The memo specifies the Hot Standby Router Protocol (HSRP). The goalof the protocol is to allow hosts to appear to use a single routerand to maintain connectivity even if the actual first hop router theyare using fails. Multiple routers participate in this protocol andin concert create the illusion of a single virtual router. Theprotocol insures that one and only one of the routers is forwardingpackets on behalf of the virtual router. End hosts forward theirpackets to the virtual router.The router forwarding packets is known as the active router. Astandby router is selected to replace the active router should itfail. The protocol provides a mechanism for determining active andstandby routers, using the IP addresses on the participating routers.If an active router fails a standby router can take over without amajor interruption in the host's connectivity. This memo alsodiscusses the ARP, MAC address, and security issues with thisprotocol.