how to understand "sh ip bgp summary" output

[Konstantin Dunaev]

Hello everybody,

I have some CPU issues with my c7200 NPE-G2 and still trying to find the source of the Problem. Wit TAC support we've found out that it's  indeed the BGP process who takes so much CPU power.  I was debugging a BGP updates and found out that some prefixes are constanly flapping, let say every 10-15 seconds. I've enabled "bgp damping" overall on my routers and it seems that  CPU load went a little bit down, but I've read  thet currently it's not recomended to use damping, but anyway.

Then something strange was observed by me in "sh ip bgp summary" output and only on NPE-G2's (NPE-G1's are pretty normal):

Router# sh ip bgp summary | i BGP path/bestpath

325006/66921 BGP path/bestpath attribute entries using 45500840 bytes of memory

the number of "BGP path" is constantly growing, quite fast, about  50-100 in a minute,  reaching about 650000 and then drops to about 250000. All NPE-G1 have constantly about 250000 "BGP path" and this number is not growing on them.

As I can observe this only on both of our NPE-G2, and as they have CPU issue, I would say it could be the source of our CPU load problem also.

Does anybody know exactly what "BGP path/bestpath" actually means and why "BGP path" is growing on NPE-G2?

I'm going to try a IOS version 122-31.SB21, currently we're using 122-31.SB13. But it can take some time, because those 2 NPE-G2's are really core routers

Thank you,

Konstantin

[lgijssel · Accepted solution]

Your conclusion seems pretty correct.

The best (and most straigthforward) solution is to perform an IOS upgrade.

Did you already check what the recommended version for your platform is?

Perhaps it is wiser to go directly to that one.

regards,

Leo

[Konstantin Dunaev]

ups, I've ocassionaly voted, never mind.

with IOS version for NPE-G2 is something strange,  the latest version in  SB train is 122-31.SB21, I was trying to compare its feature set  with the version 12.4 (T or XD) and 15.1 but Cisco's "Compare tool" shows only IOS versiobn 12.0 for NPE-G2.  And I haven't really found what is the latest recomended IOS version.

[lgijssel]

The NPE-G2 is not the most recent processor. It will probably not support the very latest releases.

I will have a quick look myself and come back if I find something useful.

Thnx for voting.

regards,

Leo

[Konstantin Dunaev]

Hi Leo,

exactly, after IOS update (SB21) the strange "BGP Path" grow is not there any more and CPU load is OK now.  I've activated the Netflow statistic and it seems woking as well. Before that, after Netflow activation I could see too many packets drops on interface and packet loss, now it's all OK.

If you could find out the "recomended" IOS version for NPE-G2. it would be nice

I can see that in the 12.4 there are other trains as in 12.2 - XD and GC, do you have an idea what is the difference?