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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This field contains a clear text 8 character reused password.

The time is given in seconds. 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.

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. For other media values between 0 and inclusive are valid. The router sends periodic Hello messages. This router is known as the active router.

Hot Standby Router Protocol

There is no RFC for version 2 of the protocol. The router is hrsp forwarding packets that are sent to the group’s virtual MAC address. Retrieved from ” https: A router cannot enter Speak state unless it has the virtual IP address. The router is a candidate to become the next active router and sends periodic Hello messages. From Wikipedia, the free encyclopedia.

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Views Read Edit View history. If multiple groups are used on a single LAN, load splitting can be achieved by distributing hosts among different standby groups. This can be useful for dual branch routers each with a single link back to the gateway. On a particular LAN, multiple hot standby groups may coexist and overlap. 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.

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

HSRP, Hot Standby Router Protocol

If the active router fails, the standby router takes over as the active router. This field describes the current state of the router sending the message.

HSRP hwrp not intended as a replacement for existing dynamic router discovery mechanisms and those protocols should be used instead whenever possible. It contains the approximate period between the Hello messages that the router sends.

To minimize network traffic, only the active and the standby routers send periodic HSRP hdrp once the protocol has completed the election process.

Hot Standby Router Protocol – Wikipedia

If the Hellotime is not configured on a router, then it MAY be learned from the Hello message from the active router. Each standby group emulates a single virtual router. This field is only meaningful in Hello messages.


This page was last edited on 28 Decemberat The router knows the virtual IP address, but is neither the active router nor the standby router. It is not compatible with version 1 HSRP. For each standby group, a single well-known MAC address is allocated to the group, as well as an IP address. In the event that the active rc fails, the standby assumes the packet forwarding duties of the active router. If the virtual IP address is not configured on a router, then it MAY be learned from the Hello message from the active router.

This field identifies the standby group. The router has not determined the virtual IP address, and not yet seen an authenticated Hello message from the active router. For Token Ring, values between 0 and 2 inclusive are valid.

In the case of routers with equal priority the router with the higher IP address wins. If a router sends a Hello message, then receivers should consider that Hello message to be valid for one Holdtime.

This is the starting state and indicates that HSRP is not running.