Difference between revisions of "Hot Standby Router Protocol"

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HSRP or Hot Standby Router Protocol is a protocol defined by Cisco and now described in [http://www.ietf.org/rfc/rfc2281.txt rfc2281].
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#Redirect [[HSRP]]
 
 
= 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 =
 
*GLBP [[Gateway Load Balancing Protocol]]
 
*VRRP [[Virtual Router Redundancy Protocol]]
 
{|
 
|-
 
|valign="top"|
 
== Configuration of R1, R2 and R3 ==
 
{|
 
|
 
<pre>
 
hostname R1
 
!
 
interface FastEthernet1/0 
 
  ip address 10.0.0.11 255.0.0.0
 
  standby priority 130
 
  standby preempt
 
  standby ip 10.0.0.1
 
</pre>
 
|
 
<pre>
 
hostname R2
 
!
 
interface FastEthernet1/0
 
  ip address 10.0.0.11 255.0.0.0
 
  standby priority 120
 
  standby preempt
 
  standby ip 10.0.0.1
 
</pre>
 
|
 
<pre>
 
hostname R3
 
!
 
interface FastEthernet1/0
 
  ip address 10.0.0.13 255.0.0.0
 
  standby priority 110
 
  standby preempt
 
  standby ip 10.0.0.1
 
</pre>
 
|}
 
 
 
= 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.<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/><br/>
 
There are no load balancing between the Routers.
 
|
 
[[Image:HSRP1.png|thumb|500px|float|Picture 1: HSRP group with Router R1 active and Router R2 and R3 as standby Routers]]
 
|}
 
 
 
[[Category:Cisco]][[Category:CCNP]][[Category:IOS]][[Category:Network]][[Category:CCNP3]]
 

Latest revision as of 07:01, 4 May 2009

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