mheusing Wed, 05/14/2008 - 03:32
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  • Cisco Employee,

Hi Parwal,


Non Stop Forwarding requires two things: a hardware platform which can continue forwarding while a Route Processor is restarting and ... trust. The neighboring routers have to trust the resetting router to forward traffic despite the fact that the control plane is not available.

NSF timers should reflect the time for an RP switchover whereas routing protocol timers are mainly used for tuning convergence after a network event. As such they serve different purposes and usually IGP timers will be lower than NSF restart timer (120 sec per default).

Have a look at the following two documents, which gave me more understanding of NSF:


"Cisco Nonstop Forwarding with Stateful Switchover Deployment Guide"

http://www.cisco.com/en/US/technologies/tk869/tk769/technologies_white_paper0900aecd801dc5e2.html


"Cisco NSF and Timer Manipulation for Fast Convergence"

http://www.cisco.com/en/US/technologies/tk869/tk769/technologies_white_paper09186a00801dce40_ps6550_Products_White_Paper.html


Hope this helps! Please use the rating system.


Regards, Martin

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