The MPLS WG Archive

["Brian Hou" <bthou@hotmail.com>]

Cheenu:

In your third scenario, the mplsOutSegmentTopLabel should be set to L2, 
instead of blank, right?

Thanks in advance for your clarification.

Brian Hou


>From: "Cheenu Srinivasan" <cheenu@alphion.com>
>To: <mpls@UU.NET>
>Subject: RE: Question about LSR MIB
>Date: Sat, 1 Sep 2001 11:14:35 -0400
>
>Bruce Nepple rote:
> > http://www.ietf.org/internet-drafts/draft-ietf-mpls-lsr-mib-07.txt
> >  describes mplsXCLabelStackIndex as identifying a stack of labels
> > to be pushed beneath the top label.  The "pushed beneath" concept
> > confuses me.  Does this assume the top label is later stripped, or
> > am I missing something completely.
>
>Here are the 3 scenarios:
>
>1. incoming label L1 is replaced with an outgoing label L2:
>      mplsOutSegmentPushTopLabel = true
>      mplsOutSegmentTopLabel     = L2
>      mplsXCLabelStackIndex      = 0
>
>2. incoming label L1 is popped and packet is forwarded with
>    whatever label stack is underneath:
>      mplsOutSegmentPushTopLabel = false
>      mplsOutSegmentTopLabel     = don't care value
>      mplsXCLabelStackIndex      = 0
>
>3. incoming label L1 is replaced with a stack of more than
>    one label: {L2, L3, L4, ... }; L2 is new top label:
>      mplsOutSegmentPushTopLabel = true
>      mplsOutSegmentTopLabel     =
>      mplsXCLabelStackIndex      = x (entry into label stack table)
>    --
>    Corresponding label stack entries:
>      entry (x, 1): mplsLabelStackLabel = L3
>      entry (x, 2): mplsLabelStackLabel = L4
>      ...
>
>Cheenu
>


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