Robust Header Compression (rohc)

NOTE: This charter is a snapshot of the . It may now be out-of-date.
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: 2005-08-15

Chair(s):

Carsten Bormann <cabo@tzi.org>
Lars-Erik Jonsson <lars-erik.jonsson@ericsson.com>

Transport Area Director(s):

Allison Mankin <mankin@psg.com>
Jon Peterson <jon.peterson@neustar.biz>

Transport Area Advisor:

Allison Mankin <mankin@psg.com>

Technical Advisor(s):

Erik Nordmark <erik.nordmark@sun.com>

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
May 2005  I-Ds of ROHC IP/UDP/RTP bis, framework and profiles separated.
Sep 2005  ROHC framework submitted to IESG for publication as Draft Standard.
Sep 2005  IP/TCP compression scheme submitted to IESG for publication as Proposed Standard
Nov 2005  ROHC IP/UDP/RTP schemes submitted to IESG for publication as Draft Standard.
Dec 2005  Possible recharter of WG to develop additional compression schemes

Internet-Drafts:

  • draft-ietf-rohc-tcp-10.txt
  • draft-ietf-rohc-rtp-impl-guide-15.txt
  • draft-ietf-rohc-tcp-field-behavior-04.txt
  • draft-ietf-rohc-rtp-rfc3095-interoperability-04.txt
  • draft-ietf-rohc-formal-notation-09.txt
  • draft-ietf-rohc-sigcomp-impl-guide-05.txt
  • draft-ietf-rohc-sigcomp-user-guide-04.txt
  • draft-ietf-rohc-over-reordering-03.txt
  • draft-ietf-rohc-sigcomp-torture-tests-03.txt
  • draft-ietf-rohc-rfc3242bis-01.txt
  • draft-ietf-rohc-rfc3095bis-improvements-01.txt

    Request For Comments:

    RFCStatusTitle
    RFC3095 PS RObust Header Compression (ROHC)
    RFC3096 I Requirements for robust IP/UDP/RTP header compression
    RFC3241 PS ROHC over PPP
    RFC3242 PS A Link-Layer Assisted ROHC Profile for IP/UDP/RTP
    RFC3243 I Requirements and assumptions for ROHC 0-byte IP/UDP/RTP compression
    RFC3320 PS Signaling Compression
    RFC3321 I SigComp - Extended Operations
    RFC3322 I Signaling Compression Requirements & Assumptions
    RFC3408 PS Zero-byte Support for Reliable Bidirectional Mode (R-mode) in Extended Link-Layer Assisted RObust Header Compression (ROHC) Profile
    RFC3409 I Lower Layer Guidelines for Robust RTP/UDP/IP Header Compression
    RFC3759 I RObust Header Compression (ROHC):Terminology and Channel Mapping Examples
    RFC3816 Standard Definitions of Managed Objects for Robus Header Compression
    RFC3843 Standard RObust Header Compression (ROHC): A Compression Profile for IP
    RFC4019 Standard RObust Header Compression (ROHC):Profiles for UDP-Lite
    RFC4077 Standard A Negative Acknowledgement Mechanism for Signaling Compression
    RFC4163 I RObust Header Compression (ROHC): Requirements on TCP/IP Header Compression
    RFC4164 Standard RObust Header Compression (ROHC):Context Replication for ROHC Profiles