Subject: Encapsulation for MPLS over AAL5

From: [email-masked]
Date: Wed, 8 Aug 2001 12:06:15 +0300

Hi all,

I'm currently learning about MPLS and ATM and I have a question
concerning the encapsulation used for MPLS.

According to RFC3035 MPLS requires null encapsulation. 
Are there any circumstances where a deviation from the RFC (i.e.
use of LLC/SNAP encapsulation) would be recommended?

Do you know how this is handled in real implementations 
(i.e. market products)?

Thanks a lot,

Jose

____________________________________________________________

Jose Mendez						 
Software Design Engineer			
Research & Development

Nokia Networks			Phone:  +49 211 9412 3341
Heltorfer Strasse 22		Mobile: +49 177 941 3341
D-40472 Düsseldorf		Fax:    +49 211 9412 3224
Germany				E-mail: [email-masked]
____________________________________________________________

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From: "Naidu, Venkata" <[email-masked]>
Date: Thu, 9 Aug 2001 10:57:29 -0400

Jose:
 
-> I'm currently learning about MPLS and ATM and I have a question
-> concerning the encapsulation used for MPLS.
-> 
-> According to RFC3035 MPLS requires null encapsulation. 

   Yes! This is true for ATM LSRs. (LC-ATM interfaces)
   http://cell-relay.indiana.edu/mhonarc/mpls/1999-Mar/msg00183.html

-> Are there any circumstances where a deviation from the RFC (i.e.
-> use of LLC/SNAP encapsulation) would be recommended?

   Two frame-based  LSRs (not ATM-LSRs) attached via a point-to-point
   link can use LLC/SNAP encapsulation.
   http://cell-relay.indiana.edu/mhonarc/mpls/1999-Jun/msg00030.html

--Venkata Naidu