From: Antonio Soares (amsoares@netcabo.pt)
Date: Thu Nov 20 2008 - 18:54:39 ARST
Well, i've seen this problem before. I made a little search with Bug Tookit and found this:
++++++++++++++++++++++++++++++++++
CSCse78533 Bug Details
Debug mpls packet shows incorrect label stack
Symptom:
Debug mpls packets shows bogus label stack.
Conditions:
When debug mpls packets is turned on.
Workaround:
Do not run debug mpls packets.
Related Bug Information
Printing incorrect label information in mpls debug
Symptom: When MPLS Traffic is sent over a TE Tunnel, the debug output produced using the command debug mpls packet produces
incorrect information about the label stack.
Workaround: There is no workaround.
++++++++++++++++++++++++++++++++++
I saw this problem in scenarios without MPLS TE.
Regards,
Antonio Soares, CCIE #18473 (R&S)
amsoares@netcabo.pt
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Pavel Bykov
Sent: quinta-feira, 20 de Novembro de 2008 20:04
To: Rich Collins
Cc: Con Spathas; ccielab@groupstudy.com
Subject: Re: MPLS EXP remarking
Since CEF is the mechanism that is working with tags, I expect FIB/LFIB to do the tag bidding.
When you debug, then it has to be process switched, so that might be responsible.
What I was thinking of though, is the exact output of debug command. Is it really EXP or CoS? Because since you are using VLANs, it
could just refer to cos markings.
Are you setting CoS as well? Can you try setting CoS?
On Thu, Nov 20, 2008 at 5:20 PM, Rich Collins <nilsi2002@gmail.com> wrote:
> Hello,
>
> I just tried a very similar scenario to yours (Uniform mode) with dynamips.
>
> If I turned on "debug mpls packet"on P1 (where the match and rewrite
> of the EXP occurs) then the policy maps/service policies wouldn't
> work. It confused me because I had seen some increment in the
> counters but that was from the time before I had activated the debug.
> So it worked properly after turning off this debug and observing
> further along in the P core such as on your R4 (enabling debug mpls
> packet here).
>
> Is there some caveat when using "debug mpls packet"?
>
> -Rich
>
>
>
> On Mon, Nov 17, 2008 at 11:40 AM, Con Spathas
> <ccie19226@googlemail.com
> >wrote:
>
> > Gday,
> >
> > I think I'm missing something quite fundamental here but I can't
> > seem to find the reason why...
> >
> > I have the following setup:
> >
> > R1 (CE) - R2 (PE) - R3 (P) - R4 (P) - R5 (PE) - R6 (CE)
> >
> > R2 is matching ICMP inbound from R1 and marking it MPLS EXP 4
> > R3 is matching MPLS EXP 4 from R2 and remarking it to MPLS EXP1
> >
> > I see that is happening when I debug on R4 (the COS=4 on the XMIT is
> > the VPN
> > label) which is what I expect as R5 is currently sending implicit
> > null to R4.
> > If I configure R5 to advertise explicit null in LDP, the debug
> > output changes correctly and the xmit CoS = 1. Anyhow that's not my
> > issue - just background info.
> >
> > R4
> > *Mar 1 02:40:51.859: MPLS: Et0/0.34: recvd: CoS=1, TTL=253,
> Label(s)=19/21
> > *Mar 1 02:40:51.863: MPLS: Et0/0.45: xmit: CoS=4, TTL=252,
> > Label(s)=21
> >
> > The bit that is eluding my understanding is the output on R3.
> >
> > R3
> > *Mar 1 00:10:59.075: MPLS: Et0/0.23: recvd: CoS=4, TTL=254,
> Label(s)=17/21
> > *Mar 1 00:10:59.079: MPLS: Et0/0.34: xmit: CoS=4, TTL=253,
> Label(s)=19/21
> >
> > I can't work out why the xmit is showing the CoS=4 - even though R4
> > does receive it as CoS=1 ? I expected on R3 to see CoS=1 on the XMIT.
> >
> > This is the policy map in have inbound on R3's connection to R2.
> >
> > class-map match-all EXP4
> > match mpls experimental topmost 4
> > !
> > policy-map IN
> > class EXP4
> > set mpls experimental topmost 1
> >
> > The policy-map output is incrementing counters correctly. So whilst
> > the re-marking is working - I don't quite understand why the debug
> > on R3
> isn't
> > consistent with what I subsequently see on R4.
> >
> > Any insight would be great. Thanks.
> >
> > Con.
> >
> >
> > Blogs and organic groups at http://www.ccie.net
> >
> > ____________________________________________________________________
> > ___ Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
>
>
> Blogs and organic groups at http://www.ccie.net
>
> ______________________________________________________________________
> _ Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
>
>
>
>
>
>
-- Pavel Bykov ------------------------------------------------- Stop the braindumps! http://www.stopbraindumps.com/Blogs and organic groups at http://www.ccie.net
This archive was generated by hypermail 2.1.4 : Mon Dec 01 2008 - 08:18:31 ARST