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Re: MPLS ICMP Extensions

  • From: Marc Binderberger
  • Date: Sun Aug 17 05:42:35 2003

As far as I remember we have seen labels from other providers, until they turned on the "traceroute hide". And there was no LDP coupling between them and us so ... . That was with Cisco in both networks.

The question is if these information cause any problem for you - despite curious customers asking ;-)

The labels seem to be allocated from a start value - usually 20, 1024, 4096 or such, depending on your system, OS version - in an incremental order, so guessing labels isn't that difficult. If your network accepts labels although it shouldn't then the extra information in ICMP doesn't really make things worse anymore.


On Thursday, August 14, 2003, at 08:39 PM, Leo Bicknell wrote:

In a message written on Thu, Aug 14, 2003 at 01:21:28PM -0500, Mike Bernico wrote:
Maybe I'm wrong, but I thought that the extended MPLS info only showed
up when the trace was started on a PE or P router. Is that right?
I did the traceroute from a router with _NO_ mpls commands turned on,
and it's on a network that uses _NO_ mpls today.

Basically from reading the draft if the router that generates the ICMP
unreachable received the packet with an MPLS label, it adds the MPLS
info to the returned data.  As long as your traceroute can parse/show
it (so far I've only confirmed Juniper can do it), it will be displayed
to the world.

       Leo Bicknell - - CCIE 3440
        PGP keys at
Read TMBG List -,
Marc Binderberger    <>    Powered by *BSD ;-)

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