Subject: RE: E2E VoIP over MPLS ('VoMPLS') Header Compression - End-to-End MPLS

From: "Ash, Gerald R (Jerry), ALABS" <[email-masked]>
Date: Thu, 20 Feb 2003 08:21:41 -0500

> I remember reading some work done on Voice over MPLS directly 
> without using RTP/UDP/IP overheads. Is that work going to be 
> a part of MPLS WG? 
> IMO, RTP/UDP/IP is a lot of overhead, compared to VoMPLS 
> approach which actually serves the same purpose (at least in 
> bearer path)

This issue was addressed in the context of a BOF ("Voice Over IP Over MPLS (vompls)") held at IETF-47, March 2000.  There are meeting notes and slides to be found at http://ietf.org/proceedings/00mar/index.html.  Antti Kankkunen (then with Integral Access) and I were the co-chairs.

The disposition was rather complicated, but here's a quick summary.

There were 2 parts to the BOF:

One thrust was Voice over MPLS *without IP*, which the IETF rejected as not within the IETF charter.  This was a push from Integral Access, which was later taken to the MPLS Forum, where an implementation agreement was eventually approved for this approach.

The second thrust was VoIP over MPLS, where two proposals were made for RTP/UDP/IP header compression, the 'simple' approach from Swallow and Berger, and another more complicated approach from Berger.  Both of these approaches were presented to the BoF and to the MPLS WG, and were both accepted by the MPLS WG for further development (as well as MPLS WG charter extension).  However, the work on these drafts didn't continue, for unclear reasons, and they expired.  

Swallow's 'simple' approach is being brought back again in one of the current drafts http://www.ietf.org/internet-drafts/draft-ash-e2e-vompls-hdr-compress-00.txt.

Hope this helps.

Thanks,
Jerry Ash