[c-nsp] BGP confusion in 12.2(18)SXE2

[Rodney Dunn]

One I missed that I learned about. I haven't looked all that closely
at it yet but it's in this same area.

CSCsb09852
Externally found severe defect: Open (O)
BGP: pathless nets not freed when updgrp members are out of sync

"
If the members of an updgrp get out of sync such that they have different table
versions from the rest of the updgrp members, then this could prevent BGP Scanner
from freeing pathless nets.  The end result is that you will see an increase in the
number of nets in your table and the number of attributes.  You may also see slower
convergence for the members of the updgrp in question.  To check if the updgrp
members are in sync do "show ip bgp update-group summary" and look at the table
version for each member.  If they have the same table version then they are fine, if not
they are out of sync.  To get the peers back in sync do "clear ip bgp * soft out".  This
will not bounce the sessions but will force BGP to re-advertise all prefixes to each
peer."


On Wed, Sep 14, 2005 at 08:54:57AM +0200, Gert Doering wrote:
> Hi,
> 
> On Tue, Sep 13, 2005 at 03:41:48PM -0700, Bruce Pinsky wrote:
> > Gert Doering wrote:
> > > I was adventurous (or maybe "stupid") enough to run 12.2(18)SXE on our
> > > Sup720 based router things.
> > > 
> > > Yesterday BGP started acting up in *very* interesting ways ("show ip b su"
> > > claimed to have seen "50" prefixes from a given peer, while the detailed
> > > commands, like "show ip b neigh x.x.x.x received-routes" displayed 
> > > *one* prefix, or just a hand ful).  
> [..]
> > > 
> > > We're running various 7200s with 12.2(18)S<n>, and these never did 
> > > funny BGP things - so I'm a bit confused whether 12.2(18)SXE2 has the
> > > same BGP code, or maybe something completely different?
> > 
> > Andre Beck reported some similar prefix counting issues in 12.2(25)S on
> > 7200's.  He indicated that the total networks reported in "show ip bgp sum"
> > was higher than he would expect.
> 
> Indeed:
> 
> 191463 network entries using 21635319 bytes of memory
> 
> on 12.2(18)SXE2, vs.
> 
> 167380 network entries using 16905380 bytes of memory
> 
> on 12.2(18)S9.
> 
> > Rodney suspects CSCeh16989 which has a fix in 12.2(30)S (no 6500 or 7200
> > image on that release), but I don't see a fix yet for 12.2SX.
> 
> Hmmm.  I do have a TAC case open on this, will throw the bug ID at
> them, and see what will happen :-) - on a router with lots of exchange
> point peers and a full table eBGP session, chances for "multiple minutes
> without a single update" are very small indeed, so it might fit.
> 
> 
> > That bug seems to have been introduced by a fix that would have been
> > integrated into 12.2(18)SXE and hence you would not have seen it in
> > 12.2(18)SXD, SXB, etc.
> 
> This fits to what Jon Lewis has been reporting - "no problems in SXD".
> 
> > The bug also claims to continually increase memory consumption, so you may
> > want to watch that for both 1) signs that this is the problem you are
> > encountering; 2) operationally impacting memory exhaustion.
> 
> The memory consumption was the reason why I initially opened the TAC
> case - the BGP process is up to over 212 Mbyte of RAM:
> 
>  PID TTY  Allocated      Freed    Holding    Getbufs    Retbufs Process
>    3   0 1191220080  194052656  212285264      54516          0 BGP Router      
> 
> ... while the 12.2(18)S9 boxes do roughly the same stuff in 130 Mb.
> 
> > If you don't need what's in that version, you may want to consider going
> > back to your previous image until this issue is resolved.
> 
> Do you think SXF would be a good idea?  Any chance of seeing this bug
> fixed in SXE"3" or SFX"2" any time soon?
> 
> We're on SXE2 because we want to use BFD - which we're not actually
> doing yet, but certainly want to enable "real soon".
> 
> thanks a lot for your help,
> 
> gert
> 
> -- 
> USENET is *not* the non-clickable part of WWW!
>                                                            //www.muc.de/~gert/
> Gert Doering - Munich, Germany                             gert at greenie.muc.de
> fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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