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 rfx be useful for dual branch routers each with a single link back to the gateway. 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.

For other media values between 0 and inclusive are valid. HSRP has the ability to trigger a failover if one or more interfaces on the router go down. It contains the amount of time that the current Hello message should be considered valid. This field contains a clear text 8 character reused password. Views Read Edit View history.

Although an arbitrary number of routers may run HSRP, only the active router forwards the packets sent to the virtual router. This field describes the current state of the router sending the message.

The router knows the virtual IP address, but is neither the active router nor the standby router. The protocol establishes an association between gateways in order to achieve default gateway failover if the primary gateway becomes inaccessible.


For each standby group, a single well-known MAC address is allocated to the group, as well as an IP address. 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 Hellotime is not configured on a router, then it MAY be learned from the Hello message from the active router.

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. In the case of routers with equal priority the router with the higher IP address wins. This is the starting state and indicates that HSRP is not running.

Hot Standby Router Protocol

This field is only meaningful in Hello messages. Each standby group emulates a single virtual router.

In the event that the active router fails, the standby assumes the packet forwarding duties of the active router.

If the standby router fails or becomes the active router, another router is elected as the standby router. It contains the approximate period between the Hello messages that the router sends.

If the Holdtime is not configured on a router, then it MAY be learned from the Hello message from the active router. To minimize network traffic, only the active and the standby routers send periodic HSRP messages once the protocol has completed the election process. A router cannot enter Speak state unless it has the virtual IP address. On a particular LAN, multiple hot standby groups may coexist and overlap. In this state the router is still waiting to hear from the active router.


The virtual IP address used by this group. HSRP is not intended as a replacement for existing dynamic router discovery mechanisms and those protocols should be used instead whenever possible. If a router sends a Hello message, then receivers should consider that Hello message to be valid for one Holdtime. It is not compatible with version 1 HSRP.

Solved: hsrp and rfc – Cisco Community

This page was last edited on 28 Decemberat This field is used to elect the active and standby routers. Retrieved from ” https: Cisco protocols First-hop redundancy protocols. The protocol is designed for use over multi-access, multicast or broadcast capable LANs e.

Another router is elected as the standby router. If multiple groups are used on a single LAN, load splitting can be achieved by distributing hosts among different standby groups. The router is a candidate to become the next active router and sends periodic Hello messages. If the active router fails, the standby router takes over as the active router.

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