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


Hope to help


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.


-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.



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