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Cell Relay Retreat>MPLS-OPS Archive>month:2002-Dec> msg00175



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Fwd: Stack

  • From: Roger Clark Williams <rogerw@nordlink.com>
  • Date: Mon, 23 Dec 2002 09:15:34 -0500
  • Resent-Date: Mon, 23 Dec 2002 10:47:17 -0500
  • To: MPLS-ops Mailing List <mpls-ops@mplsrc.com>
  • X-Sender: rogerw@together.net@207.69.200.148

Amir, in a private question to Jim Guichard I asked the same question, just
posed a different way: What are the total number of possible scenarios
labels are used for these days? Generally, the stack wouldn't go more than
3 deep (VPN label, MPLS local label, TE tunnel label), but Jim did present
a rare possible scenario with 4 labels.

It is my understanding there is nothing in the standards that specifically
limits the label depth, but there could be physical limitations of the gear
in a given network that would limit the label stack that could cross a
network. For instance, if the packet were labelled Do Not Fragment (DF) and
the link MTU size was less than the packet size, the packet would be
dropped. Normally this wouldn't be an issue for MPLS-aware gear, but for
other/older gear it may well be a concern. You can ping IP across each hop
but no VPN traffic will cross? Look for this issue as a possible problem.

I hope this helps

Roger Williams

>Resent-Date: Sun, 22 Dec 2002 07:49:30 -0500
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>From: "Amir Reza Minagar" <aminagar@hotmail.com>
>To: mpls-ops@mplsrc.com
>Date: Sun, 22 Dec 2002 15:50:00 +0330
>X-OriginalArrivalTime: 22 Dec 2002 12:20:00.0588 (UTC)
>FILETIME=[72D9D0C0:01C2A9B4]
>Subject: [MPLS-OPS]: Stack
>Resent-From: mpls-ops@mplsrc.com
>X-Mailing-List: <mpls-ops@mplsrc.com> archive/latest/5042
>X-Loop: mpls-ops@mplsrc.com
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>
>Dear All,
>
>Does anybody know if there is a maximum on the length
>of the stack in MPLS packets?
>
>Regards,
>Amir.
>
>
>
>
>
>
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