Difference between revisions of "Hot Standby Router Protocol"

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== HSRP example ==
 
== HSRP example ==
 
In picture 1 three Routers R1,R2 and R3 are setup in a HSRP Group. The Virtual IP address 10.0.0.1 and virtual MAC-Address 00-10-0C-07-AC-0A are served by the active Router R1. R1 continuesly transmits hello packets to the standby Routers.<br/>
 
In picture 1 three Routers R1,R2 and R3 are setup in a HSRP Group. The Virtual IP address 10.0.0.1 and virtual MAC-Address 00-10-0C-07-AC-0A are served by the active Router R1. R1 continuesly transmits hello packets to the standby Routers.<br/>
If the Active Router fails one of the ''standby'' Routers will become the active Router and start serving the Virtual IP address 10.0.0.1 and the virtual MAC-address 00-10-0C-07-AC-0A.<br/>
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If the Active Router fails one of the ''standby'' Routers will become the active Router and start serving the Virtual IP address 10.0.0.1 and the virtual MAC-address 00-10-0C-07-AC-0A.<br/><br/>
 
There are no load balancing between the Routers.
 
There are no load balancing between the Routers.
 
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[[Image:HSRP1.png|thumb|500px|float|Picture 1: HSRP group with Router R1 active and Router R2 and R3 as standby Routers]]
 
[[Image:HSRP1.png|thumb|500px|float|Picture 1: HSRP group with Router R1 active and Router R2 and R3 as standby Routers]]
 
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[[Category:Cisco]][[Category:CCNP]][[Category:IOS]][[Category:Network]][[Category:CCNP3]]
 
[[Category:Cisco]][[Category:CCNP]][[Category:IOS]][[Category:Network]][[Category:CCNP3]]

Revision as of 09:39, 3 May 2009

HSRP or Hot Standby Router Protocol is a protocol defined by Cisco and now described in rfc2281.

Purpose of HSRP

The purpose of HSRP is to ensure network connectivity in case of Router or access circuit failure, by having one or more standby Router(s) waiting to take over from the failing active Router.

Other high availability Router protocols

How does HSRP work

HSRP works by two or more Routers agreeing upon which Router serves the virtual Router.

The Virtual Router

The Virtual Router is a MAC-address and a IP Address the active Router serves beside its configured IP address. If the active Router fails one of the standby Routers becomes the Virtual Router by serving the virtual MAC-address and IP Address.

HSRP example

In picture 1 three Routers R1,R2 and R3 are setup in a HSRP Group. The Virtual IP address 10.0.0.1 and virtual MAC-Address 00-10-0C-07-AC-0A are served by the active Router R1. R1 continuesly transmits hello packets to the standby Routers.
If the Active Router fails one of the standby Routers will become the active Router and start serving the Virtual IP address 10.0.0.1 and the virtual MAC-address 00-10-0C-07-AC-0A.

There are no load balancing between the Routers.

Picture 1: HSRP group with Router R1 active and Router R2 and R3 as standby Routers