HSRP

• Hot Standby Router Protocol (Cisco Proprietary)

• HSRP routers exchange heartbeat packets every couple of seconds. One router has a virtual MAC address and virtual IP address (or AppleTalk, IPX, etc)

• If heartbeats stop, surviving router inherits virtual addresses from dead router.

• Works on an interface-by-interface basis; Up to 64 HSRP-aware interfaces on each router.

• Combine with a spanning-tree enabled Layer-2 network distributed throughout different buildings for best effect.