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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The router knows the virtual IP address, but is neither the active router nor the standby 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. Hdrp Wikipedia, the free encyclopedia. A router cannot enter Speak state unless it has the virtual IP address. This field identifies the standby group. When comparing priorities of two different routers, the router with the numerically higher priority wins.
This state is entered via a configuration change or when an interface first comes up. If the link of the primary router goes down, the backup router will take over the primary functionality and ffc retain connectivity to the gateway.
Hot Standby Router Protocol
This can be useful for dual branch routers each with a single link back to the gateway. The router has not determined the virtual IP address, and not yet seen an authenticated Hello message from the active router. In the case of routers with equal priority the router with the higher IP address wins. Each standby group emulates a single virtual router. If the active router fails, the standby router takes over as the active router.
HSRP is not intended as a replacement for existing dynamic router discovery mechanisms and those protocols should be used instead whenever possible.
Views Read Edit View history. A large class of legacy host implementations that do not support dynamic discovery are capable of configuring a default router. Cisco protocols First-hop redundancy protocols. For Token Ring, values between 0 and 2 inclusive are valid. For each standby group, a single well-known MAC address is allocated to the group, as well as an IP address.
This router is known as the active router.
It listens for Hello messages from those routers. In particular, the protocol protects against the failure of the first 22811 router when the source host cannot learn the IP address of the first hop router dynamically.
This is the starting state and indicates that HSRP is not running.
It contains the approximate period between the Hello messages that the router sends. This field is only meaningful in Hello messages. Version 2 of the protocol introduces stability, scalability and diagnostic improvements.
A router which is in active state MUST NOT learn new values for the Hellotime and the Holdtime from other routers, although it may continue to use values which it learned from the previous active router. For other media values between 0 and inclusive are valid. HSRP provides failover services to those hosts.
In the event that the active router fails, the standby assumes the packet forwarding duties rfv the active router. This field describes the current state of the router sending the message.
If multiple groups are used on hstp single LAN, load splitting can be achieved by distributing hosts among different standby groups. This field contains a clear text 8 character reused password. Retrieved from ” https: Another router is elected as the standby router.
Hot Standby Router Protocol – Wikipedia
A single router elected from the group is rcf for forwarding the packets that hosts send to the virtual router. If hsrpp Holdtime is not configured on a router, then it MAY be learned from the Hello message from the active router.
This page was last edited on 28 Decemberat If the Hellotime is not configured on a router, then it MAY be learned from the Hello message from the active router. If a router sends a Hello message, then receivers should consider that Hello message to be valid for one Holdtime. The time is given in seconds.