The MPLS WG Archive

["Ash, Gerald R \(Jerry\), ALABS" <gash@att.com>]

Hi All,

Please review and comment on the (significantly) updated draft 'Protocol
Extensions for Header Compression over MPLS'
(http://www.ietf.org/internet-drafts/draft-ash-avt-hc-over-mpls-protocol
-01.txt).

Note that a work item and milestone were recently added to the AVT
charter on this work:

"- in collaboration with the MPLS and ROHC WGs, to develop a solution
for header compression of RTP across MPLS networks that avoid
decompression and compression at each MPLS node.
...
Dec 05 Submit any extensions for RTP HC on MPLS networks for Proposed
Standard" 

The updated I-D responds to comments on the AVT list from Lars-Erik
Jonsson and Colin Perkins:

http://www1.ietf.org/mail-archive/web/avt/current/msg05408.html
http://www1.ietf.org/mail-archive/web/avt/current/msg05419.html
http://www1.ietf.org/mail-archive/web/avt/current/msg05428.html
http://www1.ietf.org/mail-archive/web/avt/current/msg05433.html
http://www1.ietf.org/mail-archive/web/avt/current/msg05530.html

The main changes are as follows:

1. Lars-Erik's suggested outline is used, in particular:
   - Section 2 'Terminology' is added
   - Section 3 'Header Compression over MPLS Protocol Overview' is added
   - Section 4 'Protocol Specifications' is reorganized
2. Pseudowire (PW) setup and header compression session configuration
are covered in Sections 3.1 and 4.1.  In particular, the PW Interface
Parameters Sub-TLV is used to signal header compression session setup
and header compression parameter negotiation, such as described for
header-compression-over-PPP mechanisms [RFC3241, RFC3544].
3. Encapsulation of header compressed packets is covered in Sections 3.2
and 4.2.  See in particular Figure 3 illustrating 'Header Compression
over MPLS Media Stream Transport'.
4. A PW type has been assigned to each header compression scheme, as
discussed in Section 4.1 and [IANA]
(http://ietf.org/internet-drafts/draft-ietf-pwe3-iana-allocation-11.txt)
.

Once again, please review and comment on the updated draft.  It will be
good to have some discussion on the list in anticipation of proposing
this as an AVT WG document at the IETF-63/AVT meeting.

Thanks,
Jerry

-----Original Message-----
From: i-d-announce-bounces@ietf.org
[mailto:i-d-announce-bounces@ietf.org] On Behalf Of
Internet-Drafts@ietf.org
Sent: Friday, July 08, 2005 10:50 AM
To: i-d-announce@ietf.org
Subject: I-D ACTION:draft-ash-avt-hc-over-mpls-protocol-01.txt 

A New Internet-Draft is available from the on-line Internet-Drafts
directories.


	Title		: Protocol Extensions for Header Compression
over MPLS
	Author(s)	: J. Ash, et al.
	Filename	: draft-ash-avt-hc-over-mpls-protocol-01.txt
	Pages		: 17
	Date		: 2005-7-8
	
VoIP typically uses the encapsulation voice/RTP/UDP/IP. When MPLS
   Labels are added, this becomes voice/RTP/UDP/IP/MPLS-labels. For an
   MPLS VPN, the packet header is typically 48 bytes, while the voice
   payload is often no more than 30 bytes, for example. Header
   compression can significantly reduce the overhead through various
   compression mechanisms.  MPLS is used to route header-compressed (HC)
   packets over an MPLS LSP without compression/decompression cycles at
   each router.  Such an HC over MPLS capability increases the bandwidth
   efficiency as well as processing scalability of the maximum number of
   simultaneous compressed flows that use HC at each router.  MPLS
   pseudowires are used to transport the HC context and other control
   messages between the ingress and egress MPLS label switched router
   (LSR), and the pseudowires define a point to point instance of each
   HC session at the header decompressor.  Standard HC methods (e.g.,
   ECRTP, ROHC, etc.) are re-used to determine the context.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ash-avt-hc-over-mpls-protocol-
01.txt

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