[c-nsp] slow convergence for full bgp table on a Cisco 7613/SUP720-3BXL

Ryan Harden hardenrm at uiuc.edu
Tue Mar 13 09:14:27 EST 2007

I have two suggestions as we saw a similar issue when moving from
Foundry BI-4000s to 6500s. Your results may vary.

1. Try issuing 'hold-queue 2000 in' on each peer interface. I believe
the default is 70. We did this at the suggestion of TAC. I'm not sure
how much it helped but it seemed to reduce the number of discards we
were seeing on the peering interfaces and might have sped up convergence
a bit.

2. Make sure you're not running the Modular version of IOS. Our 6506s
came with -vz onboard and we figured we'd try it out. After a week of
CPU >50% and 30-45 minutes to converge each BGP peer, we went back to
-mz. CPU dropped to ~15% and we converge in 2-3 minutes now.


Emanuel Popa wrote:
> hi,
> we are using as border router a cisco 7613 with sup720-3bxl,
> WS-X6724-SFP+DFC linecards and WS-X6704-10GE+DFC linecards.
> we had 2 x GE links with our upstream and one BGP session with full
> routing table on the loopback interfaces. everything was fine until we
> needed an upgrade. so we upgraded from 2 x GE to 1 x 10GE. our biggest
> issue is that our router needs around two hours to receive the full
> bgp table over the new session. the old session takes a maximum of
> five minutes to converge. the only difference is that one session ends
> on a 6724-SFP linecard and the other session ends on a 6704-10GE
> linecard. both of them have DFCs.
> this border router also receives the full routing table from four
> other upstream providers. the RP CPU is pretty overloaded and we are
> planning an upgrade for this machine but this is not the main issue
> right now.
> we thought that the problem comes from the BGP configuraton on the
> provider side, but we tried the same upgrade with another provider and
> we have the same kind of problem.
> i was wondering if any of you had the same problem and if you can
> share the workarounds.
> have a nice day,
> emanuel
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Ryan M. Harden, BS, KC9IHX		Office: 217-265-5192
CITES - Network Engineering		Cell:  	630-363-0365
2130 Digital Computer Lab		Fax:    217-244-7089
1304 W. Springfield	 		email:  hardenrm at uiuc.edu
Urbana, IL  61801 			

	 University of Illinois - Urbana/Champaign
                     -  All your Base -

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