Hot Standby Router Protocol (HSRP) is a protocol developed by Cisco which provides high RFC , which are defined in Finding Feature Information; Information About FHRP – HSRP MIB; How to to RFC , which are defined in 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 in

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HSRP, Hot Standby Router Protocol

This is the starting state and indicates that HSRP is not running. This can be useful for dual branch routers each with a single link back to the gateway. This set is known as an HSRP group or a standby group. The router has not determined the virtual IP address, and not yet seen an authenticated Hello message from the active router.

In particular, the protocol protects against the failure of the first hop router when the source host cannot learn the IP address of the first hop router dynamically. The router is a candidate to become the next active router and sends periodic Hello messages. Gfc the case of routers with equal priority the router with the higher IP address wins. HSRP is not intended as a replacement for existing dynamic router discovery mechanisms and those protocols should be used instead whenever possible.

If the standby router fails or becomes the active router, another router is elected as the standby router. This field is used to elect the active and standby routers. HSRP is not a routing protocol tfc it does not advertise IP routes or affect the routing table in any way.


Cisco protocols First-hop redundancy protocols. This field is only meaningful in Hello hzrp. If the virtual IP address is not configured on a router, then it MAY be learned from the Hello message from the rf router. This page was last edited on 28 Decemberat The router is currently forwarding packets that are sent to the group’s virtual MAC address.

Another router is elected as the standby router. If the Hellotime is not configured on a router, then hsrpp MAY hsrl learned from the Hello message from the active router.

There is no RFC for version 2 of the protocol.

Version 2 of the protocol introduces stability, scalability and diagnostic improvements. HSRP has the ability to trigger a failover if one or more interfaces on the router go down. The virtual IP address used by this group. A router which is in active state MUST NOT learn new values for the Hellotime and the Holdtime from other routers, hspr it may continue to use values which it learned from hsp previous active router.

Although an arbitrary number of routers may run HSRP, only the active router forwards the packets sent to the virtual router.

It contains the approximate period between the Hello messages that the router sends. This field describes the current state of the router sending the message.

tfc The router sends periodic Hello messages. To minimize network traffic, only the active and the standby routers send periodic HSRP messages once the protocol has completed the election process. If the active router fails, the standby router takes over as the active router. A router cannot enter Speak state unless it has the virtual IP address. HSRP provides failover services to those hosts. This field identifies the standby group.


This state is entered via a configuration change 22281 when an interface first comes up.

If a router sends a Hello message, then receivers should consider that Hello message to be valid for one Holdtime. This router is known as the active router. Views Read Edit View history. It contains 281 amount of time that the current Hello message should be considered valid.

In this state gsrp router is still waiting to hear from the active router. On a particular LAN, multiple hot standby groups may coexist and overlap. The router knows the virtual IP address, but is neither the active router nor the standby router. The time is given in seconds. If multiple groups are used on a single LAN, load splitting can be achieved by distributing hosts among different standby groups.

Hot Standby Router Protocol

The protocol is designed for use over multi-access, multicast or broadcast capable LANs e. This field contains a clear text 8 character reused password. It listens for Hello messages from those routers.

The protocol establishes an association between gateways in order to achieve default gateway failover if the primary gateway becomes inaccessible. By using this site, you agree to the Terms of Use and Privacy Policy.

A large class of legacy host implementations that do not support dynamic discovery are capable of configuring a default router. From Wikipedia, the free encyclopedia.