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

[Emanuel Popa]

Ytti,

Here is the output:
br01.frankfurt#sh int te 10/3 | i Input queue
  Input queue: 0/75/109/109 (size/max/drops/flushes); Total output drops: 0

But:

- routing protocol packets are not dropped when default hold queue of
75 is full; they are considered priority packets and they are dropped
after headroom of 1000 is full; please see
http://www.cisco.com/en/US/products/hw/routers/ps167/products_tech_note09186a008012fb87.shtml
for more details

- PMTUD is enabled and we have a good data segment on this session:
br01.frankfurt#sh ip bgp neighbors A.B.C.D | i segment
Datagrams (max data segment is 1440 bytes):

Thanks,
Emanuel


On 3/13/07, Saku Ytti <saku+cisco-nsp at ytti.fi> wrote:
> On (2007-03-13 15:50 +0200), Emanuel Popa wrote:
>
> > 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.
>
> Do you have input queue drops:
> LAB-P1#sh int giga1/1 | i Input
>   Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
>
> If so, increase it, I can't think of any issue increasing it to maximum,
> but perhaps 1000 for a start.
>
> btw. takes around minute for me, which is way too much and Cisco opened
> case because they couldn't immediately explain what is capping the
> convergency, CSCsh81034.
>
> You might also want to run PMTUD, but lack of it, can't cause
> issues this severe.
>
> --
>   ++ytti
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