Robust Header Compression (rohc)

In addition to this official charter maintained by the IETF Secretariat, there is additional information about this working group on the Web at:

Additional ROHC Page

Last Modified: 2006-08-22

Additional information is available at tools.ietf.org/wg/rohc

Chair(s):

Lars-Erik Jonsson <lars-erik.jonsson@ericsson.com>

Transport Area Director(s):

Magnus Westerlund <magnus.westerlund@ericsson.com>

Lars Eggert <lars.eggert@netlab.nec.de>

Transport Area Advisor:

Magnus Westerlund <magnus.westerlund@ericsson.com>

Technical Advisor(s):

Erik Nordmark <erik.nordmark@sun.com>

Carsten Bormann <cabo@tzi.org>

Mailing Lists:

General Discussion: rohc@ietf.org
To Subscribe: rohc-request@ietf.org
Archive: http://www.ietf.org/mail-archive/web/rohc/index.html

Description of Working Group:

Due to limited bandwidth, IP/UDP/RTP/TCP packets sent over cellular
links benefit considerably from header compression. Existing header
compression schemes (RFC 1144, RFC 2508) do not perform well over
cellular links due to high error rates and long link roundtrip times,
particularly as topologies and traffic patterns become more
complex. In addition, existing schemes do not compress TCP options
such as SACK or Timestamps.

Another consequence of low bandwidth links is long session setup
delays when text-based signaling protocols, such as SIP and SDP, are
used. These delays can be significantly reduced by compressing not
only the headers, but also the signaling information.

The goal of ROHC is to develop generic header compression schemes that
perform well over links with high error rates and long roundtrip
times, as well as related signaling compression schemes. The schemes
must perform well for cellular links built using technologies such as
WCDMA, EDGE, and CDMA-2000. However, the schemes should also be
applicable to other future link technologies with high loss and long
roundtrip times. Ideally, it should be possible to compress over
unidirectional links.

Good performance includes both minimal loss propagation and minimal
added delay. In addition to generic TCP and UDP/RTP compression,
applications of particular interest are voice and low-bandwidth
video.

ROHC may develop multiple compression schemes, for example, some that
are particularly suited to specific link layer technologies. Schemes
in addition to those listed in the milestones below may be added in
consultation with the area directors.

A robust compression scheme must:

* assure that the result after decompression is semantically identical
to the uncompressed original;

* perform well when the end-to-end path involves more than one
cellular link;

* support IPv4 and IPv6.

* provide benefit in the presence of IPSEC.

Creating more thorough requirements documents will be the first task
of the WG for each of its specific areas of work, which are:

* 0-byte improvements to RTP header compression

* TCP header compression

* Signaling compression

* SCTP header compression

In addition, the WG will work on MIBs for its compression schemes, as
well as the sheperding of RFC3095 to draft standard.

The working group shall maintain connections with other
standardization organizations developing cellular technology for IP,
such as 3GPP and 3GPP-2, to ensure that its output fulfills their
requirements and will be put to good use.

In addition, the WG should develop a solid understanding of the impact
that specific error patterns have on the compression schemes, and
document guidelines to Layer 2 designers regarding what Layer 2
features work best to assist Layer 3 and Layer 4 header compression.
This work is in coordination with the PILC WG.

Some of the schemes developed in ROHC will be used in wider contexts
than just the specific link technologies discussed. The working group
will ensure the applicability in particular of the TCP and signaling
compression schemes to the general Internet. This includes
considering the applicability of the technologies under consideration
to open-source implementations.

Finally, working group documents will address interactions with IPSEC
and other security implications.

Goals and Milestones:

Done		Submit I-D on Requirements for IP/UDP/RTP header compression.
Done		Submit I-D of layer-2 design guidelines.
Done		Submit I-D(s) proposing IP/UDP/RTP header compression schemes.
Done		Submit I-D of Requirements for IP/TCP header compression.
Done		Requirements for IP/UDP/RTP header compression submitted to IESG for publication as Informational.
Done		Resolve possibly multiple IP/UDP/RTP compression schemes into a single scheme.
Done		Submit I-D on IP/TCP header compression scheme.
Done		IP/UDP/RTP header compression scheme submitted to IESG for publication as Proposed Standard.
Done		Layer-2 design guidelines submitted to IESG for publication as Informational.
Done		Initial draft on general signaling compression security analysis.
Done		Requirements and assumptions for signaling compression
Done		Signaling compression scheme submitted to IESG for publication as Proposed Standard, including security approach for SIP compression usage.
Done		General signaling compression security analysis submitted to IESG for publication as Informational.
Done		ROHC MIB submitted to IESG for publication as Proposed Standard.
Done		ROHC IP-only profile submitted to IESG for publication as Proposed Standard
Done		ROHC UDP Lite schemes submitted to IESG for publication as Proposed Standard.
Done		Requirements for IP/TCP header compression submitted to IESG for publication as Informational.
Done		Problem analysis ROHC-over-channels-that-can-reorder-packets submitted to IESG for publication as Informational
Feb 2006		I-Ds of ROHC IP/UDP/RTP bis, framework and profiles separated.
Feb 2006		RFC 3095 Implementer's Guide submitted to IESG for publication as Proposed Standard
Mar 2006		IP/TCP compression scheme submitted to IESG for publication as Proposed Standard
May 2006		ROHC framework submitted to IESG for publication as Proposed Standard
May 2006		Revised ROHC IP/UDP/RTP profiles submitted to IESG for publication as Proposed Standard
Jun 2006		Recharter of WG to develop additional profiles if needed, or possible additional compression schemes. Consideration of concluding the working group.

Internet-Drafts:

RObust Header Compression (ROHC): A Profile for TCP/IP (ROHC-TCP) (181601 bytes)
RObust Header Compression (ROHC): Corrections and Clarifications to RFC 3095 (69961 bytes)
Formal Notation for Robust Header Compression (ROHC-FN) (122241 bytes)
Implementer's Guide for SigComp (49426 bytes)
Applying Signaling Compression (SigComp) to the Session Initiation Protocol (SIP) (33433 bytes)
Improvements for the ROHC Profile Set Update (25441 bytes)
Integration of Header Compression over IPsec Security Associations (31323 bytes)
The RObust Header Compression (ROHC) Framework (81458 bytes)

Request For Comments:

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