redundant switch supervisors

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Jan 25th, 2009
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Hi every body!

I was reading about redundancy in switch supervisors.


There are different modes:

1) route processor redundancy(RPR)


2)Route processor redundancy(RPR+)


3)stateful switchover (SSO)



q1)I understand how these modes but my question is why one want to use any other mode but sso as fail over time is less than a second compared to other modes ?



q2) Should both supervisors be same?



Thanks a lot!

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Giuseppe Larosa Mon, 01/26/2009 - 00:44
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Hello Sarah,


q1) SSO requires identical supervisors, identical ios image and newer IOS image (it has more tight requirements) so there can be cases where RPR or RPR+ can be used but SSO cannot


q2) for SSO they need to be exactly the same model, RPR and RPR+ have lesser requirements


see


http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/46sg/configuration/guide/RPR.html#wp1116237


Hope to help

Giuseppe


sarahr202 Mon, 01/26/2009 - 21:11
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thanks a lot Giuseppe!

My book says

For RPR+ ios must be of same release. How about sup? they should be same as well?

Amit Singh Mon, 01/26/2009 - 21:22
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The sups' have to be the same as well.


regards,

-amit singh

Kerem Gursu Mon, 01/26/2009 - 01:19
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Hi ,


There are several modes , but every mode has its own unique circumstances. The fastest mode is not always the best mode


1)SSO enables subsecond convergence , but some state tables like HSRP encounters problems during the switchover. For example if your supervisors or RPs switch faster than your HSRP timeout , you will definetely experience a switchover in the HSRP state as well.


2) The Supervisors / RPs must be the same.


HTH

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