Subject: can egress know the ingress of a packet?

From: Tan Su Wei <[email-masked]>
Date: Tue, 30 May 2000 02:39:33 +0000

Dear all,

    I'd a doubt on :
        In a mpls network domain, for a particular ingress-egress pair
with multiple LSPs in between them, is it possible when a packet reach
the engress node, the engress node will know the following:
        i. ) the ingress node
        ii.) the lsp it travel

        Thanks for any reply.

Regards
Tan Su Wei

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From: "Pathangi N Janardhanan" <[email-masked]>
Date: Tue, 30 May 2000 08:47:45 +0530

Hi,

> the engress node, the engress node will know the following:
  Either the label on the incoming packet or the combination of label
and interface of the
incoming packet can be used to identify the ingress/LSP of the
incoming packet.

Thanks
Jana

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From: [email-masked] (David Wilder)
Date: Tue, 30 May 2000 10:01:01 -0400 (EDT)

Can we use the Record route Object for this?

Dave

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From: Rohit Chhapolia <[email-masked]>
Date: Tue, 30 May 2000 10:12:31 -0400

To determine the ingress node, "Extended Tunnel ID" is useful.

From RSVP-TE draft,

      Extended Tunnel ID

         A 32-bit identifier used in the SESSION that  remains  constant
         over  the  life  of  the  tunnel.   Normally  set to all zeros.
         Ingress nodes that wish to narrow the scope of a SESSION to the
         ingress-egress  pair  may  place  their  IPv4 address here as a
         globally unique identifier.

-- 
Rohit Chhapolia
Globespan, Inc.
mailto:[email-masked]
http://www.globespan.net

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From: David Charlap <[email-masked]>
Date: Tue, 30 May 2000 10:49:45 -0400

>        globally unique identifier.

I wouldn't use this for that purpose.  Note that the draft says "may",
not "must" or "shall".

This use of extended tunnel ID, while recommended and common, is not a
requirement.  In theory, any value may be used as long as it uniquely
identifies the sender withing the MPLS cloud.  This ID could be
something other than IP address.

-- David