NSF Timers

NAVIN PARWAL · ‎05-10-2008

Hello,

Folks, when tunning NSF timers would should be the recommendations it terms of routing protcols timers? should nsf timers be lower than routing protcols timers?

Thanks

mheusing · ‎05-14-2008

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