In computer networking, the Hot Standby Router Protocol (HSRP) is a Ciscoproprietary redundancy protocol for establishing a fault-tolerantdefault gateway. Version 1 of the protocol was described in RFC 2281 in 1998. Version 2 of the protocol includes improvements and supports IPv6 but there is no corresponding RFC published for this version.
The protocol establishes an association between gateways in order to achieve default gateway failover if the primary gateway becomes inaccessible. HSRP gateways send multicasthello messages to other gateways to notify them of their priorities (which gateway is preferred) and current status (active or standby).
The primary router with the highest configured priority will act as a virtual router with a pre-defined gateway IP address and will respond to the ARP or ND request from machines connected to the LAN with a virtual MAC address. If the primary router should fail, the router with the next-highest priority would take over the gateway IP address and answer ARP requests with the same MAC address, thus achieving transparent default gateway failover.
In the virtual MAC address, Xs represent the group ID in hex.
HSRP is not a routing protocol as it does not advertise IP routes or affect the routing table in any way.
HSRP has the ability to trigger a failover if one or more interfaces on the router go down. This can be useful for dual branch routers each with a single link back to the gateway. If the link of the primary router goes down, the backup router will take over the primary functionality and thus retain connectivity to the gateway.
Version 2
Version 2 of the protocol introduces stability, scalability and diagnostic improvements. It is not compatible with version 1 HSRP.[1] There is no RFC for version 2 of the protocol.
Provides IPv6 support
Increases the number of HSRP groups from 256 to 4096
Gruszczyk, Katarzyna; Szukała, Krzysztof. . Supervised and led by Dawid Mentel. Archived from the original on 2009-06-06.
External links
Cisco: HSRP Features
March 29, 2023
standby, router, protocol, confused, with, high, availability, seamless, redundancy, computer, networking, hsrp, cisco, proprietary, redundancy, protocol, establishing, fault, tolerant, default, gateway, version, protocol, described, 2281, 1998, version, proto. Not to be confused with High availability Seamless Redundancy In computer networking the Hot Standby Router Protocol HSRP is a Cisco proprietary redundancy protocol for establishing a fault tolerant default gateway Version 1 of the protocol was described in RFC 2281 in 1998 Version 2 of the protocol includes improvements and supports IPv6 but there is no corresponding RFC published for this version The protocol establishes an association between gateways in order to achieve default gateway failover if the primary gateway becomes inaccessible HSRP gateways send multicast hello messages to other gateways to notify them of their priorities which gateway is preferred and current status active or standby Contents 1 Operation 2 Version 2 3 See also 4 References 5 Further reading 6 External linksOperation EditThe primary router with the highest configured priority will act as a virtual router with a pre defined gateway IP address and will respond to the ARP or ND request from machines connected to the LAN with a virtual MAC address If the primary router should fail the router with the next highest priority would take over the gateway IP address and answer ARP requests with the same MAC address thus achieving transparent default gateway failover HSRP version IP protocol Group address UDP port Virtual MAC address range1 IPv4 224 0 0 2 all routers 1 1985 00 00 0c 07 ac XX2 IPv4 224 0 0 102 HSRP 1 1985 00 00 0c 9f fX XXIPv6 ff02 66 2029 00 05 73 a0 0X XXIn the virtual MAC address Xs represent the group ID in hex HSRP is not a routing protocol as it does not advertise IP routes or affect the routing table in any way HSRP has the ability to trigger a failover if one or more interfaces on the router go down This can be useful for dual branch routers each with a single link back to the gateway If the link of the primary router goes down the backup router will take over the primary functionality and thus retain connectivity to the gateway Version 2 EditVersion 2 of the protocol introduces stability scalability and diagnostic improvements It is not compatible with version 1 HSRP 1 There is no RFC for version 2 of the protocol Provides IPv6 support Increases the number of HSRP groups from 256 to 4096See also EditVirtual Router Redundancy Protocol standards based alternative to HSRP Gateway Load Balancing Protocol Cisco proprietary router redundancy solution providing load balancing Common Address Redundancy Protocol open source patent free and unrestricted alternative to HSRP and VRRP First hop redundancy protocols List of default gateway redundancy protocolsReferences Edit a b c First Hop Redundancy Protocols Configuration Guide Cisco IOS Release 15M amp T Cisco Systems retrieved 2016 05 28Further reading EditGruszczyk Katarzyna Szukala Krzysztof Configuration of HSRP Protocol on the sample network topology Supervised and led by Dawid Mentel Archived from the original on 2009 06 06 External links EditCisco HSRP Features Retrieved from https en wikipedia org w index php title Hot Standby Router Protocol amp oldid 1056478961, wikipedia, wiki, book, books, library,
