High CPU Utilization short duration

[c.vergara]

I have a GSR and have high CPU Utilization by short duration due BGP Scanner process. The router has 15 BGP sesion, 4 Full BGP. I´m seeing with show ip bgp summary command some peer constantly deletion and reinsertion prefix received and the version table increase, in adittion say scan interval is 15 secs.

How can i to crrect this situation ?

the above, can affect to some other process on the router? (ie.console, pings)

[Gilles Dufour]

This is normal.

BGP scanner will scan the routing table every minute and it will use as much CPU as it can. So, if you have a huge routing table, BGP scanner will most likely need all available CPU.

This process has a low priority, so it will give back CPU if another process needs it.

[c.vergara]

OK, I understand that is a normal process, bug What happen with the constant deletion and reinsertion prefix received and the increase version table ?

[Gilles Dufour]

that is also normal :-)

There is a lot of routes in the Internet routing table (> 100k) and unfortunately, not all the routes are stable. So, you will see routes leaving and coming back very frequently (all the time actually).

There is a feature called route dampening to alleviate the problem of instable routes. But, if your not an ISP, I would not suggest to use it.

Regarding the high CPU due to BGP scanner, I forgot to mention this is documented on the web at the following url :

http://www.cisco.com/warp/public/459/highcpu-bgp.html

Gilles.