[c-nsp] traceroute shows mpls labels...how?

Wed Aug 22 16:27:17 EDT 2012

Yes wireshark should see the info.  There are a couple rfcs for the extensions but I don't know what they are offhand.  Does not require anything special in the client ICMP packet and only applies to TTL Exceeded and Dest Unreachable responses.  

Phil

Sent from my iPad

On Aug 22, 2012, at 4:22 PM, "Aaron" <aaron1 at gvtc.com> wrote:

> That’s what I was looking for.  So is it a part of the mpls lsr’s icmp implementation that would allow those icmp extensions to carry and send that info or the traceing device (windows) or both?  In other words, I wonder if the windows device actually is rcv’ing the icmp extended packets carrying that mpls label info BUT the tracert windows application just isn’t smart enough to render it on the cli output….  I would think that wireshark on windows would tell me if it is or isn’t seeing those extensions with the label info
>  
> Aaron
>  
> From: Chris Evans [mailto:chrisccnpspam2 at gmail.com] 
> Sent: Wednesday, August 22, 2012 3:03 PM
> To: Phil Bedard
> Cc: &lt,cisco-nsp at puck.nether.net&gt,; Aaron
> Subject: Re: [c-nsp] traceroute shows mpls labels...how?
>  
> Also this depends on vendor too.  IIRC junos uses udp for its trace routing and ios uses icmp.    Meaning that if you did traceroute from a cisco box going over a juniper network the labels wouldn't show and vice versa.   You brought up something I was 100% suee about a few years ago but those brain cells are gone.  
> 
> On Aug 22, 2012 2:58 PM, "Phil Bedard" <philxor at gmail.com> wrote:
> There are ICMP extensions to carry MPLS label stack information but the trace route application needs to support it.   The windows client doesn't.
> 
> Phil
> 
> Sent from my iPad
> 
> On Aug 22, 2012, at 3:21 PM, "Aaron" <aaron1 at gvtc.com> wrote:
> 
> > Do you all know how this works?  How is traceroute able to report back the
> > mpls label that is in use in the transit hops?  Also wondering why I don't
> > see this on windows command line tracert
> >
> >
> >
> > Aaron
> >
> >
> >
> >
> >
> > RP/0/RSP0/CPU0:9k#trace vrf one 1.2.3.4 source 2.4.6.8
> >
> >
> >
> > 1  19.1911.5 [MPLS: Labels 16001/16220 Exp 0] 2 msec  1 msec  0 msec
> >
> > 2  19.1911.1 [MPLS: Label 16220 Exp 0] 0 msec  0 msec  1 msec
> >
> > 3  88.88.191.22 0 msec  0 msec
> >
> >    19.1911.33 1 msec
> >
> > 4  88.88.191.18 1 msec  1 msec  0 msec
> >
> > 5  88.88.135.221 10 msec  10 msec  11 msec
> >
> > 6  122.47.236.130 [MPLS: Label 17039 Exp 1] 47 msec  49 msec  51 msec
> >
> > 7  122.47.154.53 [MPLS: Labels 0/17017 Exp 1] 48 msec  49 msec  47 msec
> >
> > 8  122.45.30.134 [MPLS: Labels 23417/17016 Exp 1] 48 msec  49 msec  47 msec
> >
> > 9  122.45.1.17 [MPLS: Labels 23439/17016 Exp 1] 50 msec  49 msec  51 msec
> >
> > 10 122.45.31.189 [MPLS: Labels 0/17016 Exp 1] 51 msec  54 msec  51 msec
> >
> > 11 122.45.158.34 [MPLS: Labels 0/16009 Exp 1] 49 msec  50 msec  47 msec
> >
> > 12 122.45.104.49 46 msec  46 msec  47 msec
> >
> > 13 122.45.108.14 47 msec  47 msec  47 msec
> >
> > 14  *  *  *
> >
> > 15  *  *  *
> >
> > 16  *
> >
> >
> >
> > _______________________________________________
> > cisco-nsp mailing list  cisco-nsp at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> 
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/