Hot Standby Router Protocol
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Hot Standby Router Protocol (HSRP) is a Cisco proprietary routing protocol for fault-tolerant routing, and has been described in detail in RFC 2281. The Virtual Router Redundancy Protocol VRRP is a standards-based alternative to HSRP defined in IETF standard RFC 3768.
The protocol establishes a framework between network routers in order to achieve failover routes if the primary route should become inaccessible, 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) using UDP port 1985, to other HSRP-enabled routers, defining priority between the routers, the primary router with the highest configured priority will act as a virtual router with its own IP and MAC address, which the hosts on the local segment will be configured to use as a gateway to the destination in question. If the primary router should fail, or the link to the destination drop, the router with the next-highest priority would take over communications through alternative routes within seconds, without major interruption to network connectivity.
See also
- VRRP Standards-based alternative to HSRP
- GLBP Cisco proprietary router redundancy solution providing load balancing
- CARP Common Address Redundancy Protocol
External link
- Cisco: HSRP Features (http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094a91.shtml)
- Cisco: Using HSRP for Fault-Tolerant IP Routing (http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/cs009.htm)de:Hot Standby Router Protocol