[c-nsp] The mechanics of SSO

Daryl G. Jurbala daryl at introspect.net
Sun May 10 15:55:21 EDT 2009

On May 7, 2009, at 11:32 AM, Ross Vandegrift wrote:

> On Thu, May 07, 2009 at 02:03:44AM +0300, Ibrahim Abo Zaid wrote:
>> actually i can't get if SUP running SSO why you think configuration  
>> will be
>> loaded from active to standby during switchover ? !
>> SSO maintains control plane and data plane resiliency and both SUP  
>> have
>> active IOS image and synchronized configuration
> Not during switchover - during bootup.  When the standby SUP is
> booting, it needs to fetch the config from the active.
> That is the syncronization problem I ran into yesterday.

I believe Jared meant that you would need to interrupt the boot  
process of one of the sups so that it WON'T boot during power up.   
Once you have one Sup fully online with all modules initialized, you  
can reset the one that you interrupted and let it boot.  And I agree  
with him.  It looks like a race condition that is happening because of  
HA initialization timing during boot with both Sups.

Sure, if you happen to have physical access you can ignore that OOB  
thing and just pop a sup out, boot, and pop it back in once everything  
else is online.  But I think most of us are used to working on  
equipment that is somewhere between "fairly inconvenient" and "20 hour  
flight" to physically access, so my default response is usually how to  
do things over the wire or though OOB as well.


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