Subject: RE: Question about LSR MIB

From: "Cheenu Srinivasan" <[email-masked]>
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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From: [email-masked]
Date: Sun, 2 Sep 2001 10:48:15 +0200

Cheenu,

>      mplsXCLabelStackIndex      = 0

This case assumes pop-and-go for L1. Correct?

Regards,

     Francis.

--------------------------------

"Cheenu Srinivasan" <[email-masked]> on 01/09/2001 17:14:35

 To:      [email-masked]                                         
                                                              
 cc:      (bcc: Francis ARTS/BE/ALCATEL)                      

 Subject: RE: Question about LSR MIB                          

Cheenu

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From: "Brian Hou" <[email-masked]>
Date: Sun, 02 Sep 2001 14:36:52

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" <[email-masked]>
>To: <[email-masked]>
>Date: Sat, 1 Sep 2001 11:14:35 -0400
>
>Bruce Nepple rote:

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From: Cheenu Srinivasan <[email-masked]>
Date: Tue, 4 Sep 2001 10:40:31 -0400

> This case assumes pop-and-go for L1. Correct?

Yes.

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From: Cheenu Srinivasan <[email-masked]>
Date: Tue, 4 Sep 2001 10:42:15 -0400

> In your third scenario, the mplsOutSegmentTopLabel should be 

Sorry - the "blank" was a typo and shd be L2.