Subject: Frame Relay Encapsulation

From: "Ramakrishnan.R (Networking) - CTD, Chennai." <[email-masked]>
Date: Sat, 4 Jan 2003 17:35:52 +0530

Hello,
  I am working on MPLS over Frame Relay. I would like to know how the MPLS
packet is encapsulated in the Frame Relay packet. I would like to know what
is the NLPID ( A field in the MPLS header) used for MPLS?. I couldn't get
the information about the NLPID anywhere.

Thanks in Advance.
Regards
Ramki

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From: "v.nagasrinivas" <[email-masked]>
Date: Sun, 05 Jan 2003 11:28:52 +0530

Hi Ramakrishnan,

            I think rfc 3034 is explaining how it will do ... I quickly
browsed and the following
is helping you.   http://www.zvon.org/tmRFC/RFC3034/Output/chapter5.html

http://www.networksorcery.com/enp/protocol/framerelay.htm
and go through frf8.1 for some more information, not relating to MPLS.

Thanks,
srinivas.

--
office ph: 091-40-3607619

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From: "Andrew G. Malis" <[email-masked]>
Date: Sun, 05 Jan 2003 10:20:09 -0500

http://www.ietf.org/rfc/rfc3034.txt is the reference.  See section 4 for 
the encapsulation.  As you'll see, it's very straightforward.

In particular, no NLPID (for multiprotocol identification) is required 
because FR VCs used as MPLS LSPs are dedicated to that use.  That's why you 
couldn't find a specific reference.

Cheers,
Andy

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From: Dan Tappan <[email-masked]>
Date: Mon, 06 Jan 2003 09:37:48 -0500

At 10:20 AM 1/5/2003 -0500, Andrew G. Malis wrote:
>because FR VCs used as MPLS LSPs are dedicated to that use.  That's why 
>you couldn't find a specific reference.

While the above is technically correct, I don't know of anyone who has 
actually implemented rfc3034.

A more common approach for carrying MPLS across a FR link is to follow 
rfc2427: using the LLC/SNAP (section 4.1) encapsulation above the rfc3032 
encapsulation.

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From: "Andrew G. Malis" <[email-masked]>
Date: Mon, 06 Jan 2003 16:43:44 -0500

Dan,

It depends on the usage - if you're using FR switches as LSRs, and using 
MPLS as the control plane to allocate the DLCIs, then you must use RFC 
3034.  However, if you're simply tunneling MPLS packets through a FR 
network which uses a native control plane, or perhaps FRF.5 across an ATM 
backbone and control plane, then you are correct.

I was aware of a couple of implementations of RFC 3034 at the time we were 
working on the draft.  Unfortunately, one of the places has closed up shop, 
and the other seems to have been either discontinued or never made it into 
a shipping release.  It looks like the RFC may never make it past Proposed ....

Cheers,
Andy

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From: Kireeti Kompella <[email-masked]>
Date: Tue, 14 Jan 2003 11:17:55 -0800 (PST)

On Sat, 4 Jan 2003, Ramakrishnan.R (Networking) - CTD, Chennai. wrote:

> packet is encapsulated in the Frame Relay packet.

SNAP encoding with the Ethertype for MPLS.

Kireeti.