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BGP Table version incrementing rapidly

Hi,

I have 2 x 7507s that provide our internet connectivity. It was noticed that they are both incrementing their BGP table numbers at more than one a second. (sometimes quite a lot more)

I've tried to use the command show ip bgp flap-statistics but this returns nothing. Dampening is not running and the utilisation is as below :

router1#show proc cpu

CPU utilization for five seconds: 3%/2%; one minute: 8%; five minutes: 10%

However, the history shows regular peaks. (in attachment)

I think these table increments may be giving the router a few issues and may be contributing to a wider problem.

How can I identify the routes that ae flapping or is there something else that can cause the table number to increment. The BGP peers have been up for a long time.

Many Thanks in advance

Dan

I can't seem to add the attachment. So here they are (you may need to cut and paste to something with monospacing to see it properly)

5468876645788775468876466998656678764578876457876555787544

5854732284443347731500999002970655726836692685583528643861

100

90 * * ** * ** *

80 ** ** ** *** *** *** *** **

70 **** ***** *** ****** **** **** *** ***

60 * ****** ****** ***** ************* ****** ****** *****

50 *********************************************************

40 **********************************************************

30 **********************************************************

20 **********************************************************

10 ##########################################################

0....5....1....1....2....2....3....3....4....4....5....5....

0 5 0 5 0 5 0 5 0 5

CPU% per minute (last 60 minutes)

* = maximum CPU% # = average CPU%

9989899999889988888989898888888888889988888989888888898888888888889988

0491803195972064778054607779899487622065775093781549207225765718780084

100 **

90 *************** *************** *** ************ * * ** ***** ******

80 **********************************************************************

70 **********************************************************************

60 **********************************************************************

50 **********************************************************************

40 **********************************************************************

30 **********************************************************************

20 **********************************************************************

10 ######################################################################

0....5....1....1....2....2....3....3....4....4....5....5....6....6....7.

0 5 0 5 0 5 0 5 0 5 0 5 0

CPU% per hour (last 72 hours)

1 REPLY

Re: BGP Table version incrementing rapidly

Hi Dan,

the BGP table version increases with every BGP update received. So whever there is a network announced or removed from the internet, more then, when a path to a network is modified, an update is sent and the BGP table increases.

Your CPU load shows nothing abnormal. Two processes "BGP scanner" and "BGP router" mainly contribute to CPU load on a BGP speaker. Once per minute the reachability from every next hop is checked for every path in your BGP table. And all BGP updates are processed using all free CPU cycles.

So having once per minute a CPU load of 100% is the norm and not an exception.

Your average CPU is quite fine, even 30% would be ok.

Regards, Martin

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