Robust Header Compression (rohc)

Robust Header Compression (rohc)
--------------------------------

Charter
Last Modified: 2007-09-28

Current Status: Active Working Group

Chair(s):
Carl Knutsson <[email protected]>

Transport Area Director(s):
Magnus Westerlund <[email protected]>
Lars Eggert <[email protected]>

Transport Area Advisor:
Magnus Westerlund <[email protected]>

Technical Advisor(s):
Erik Nordmark <[email protected]>
Carsten Bormann <[email protected]>

Mailing Lists:
General Discussion:[email protected]
To Subscribe: [email protected]
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

Done I-Ds of ROHC IP/UDP/RTP bis, framework and profiles separated.

Done RFC 3095 Implementer's Guide submitted to IESG for publication
as Proposed Standard

Done IP/TCP compression scheme submitted to IESG for publication as
Proposed Standard

Done ROHC framework submitted to IESG for publication as Proposed
Standard

Done SigComp for SIP submitted to IESG for publication as Proposed
Standard

Dec 2006 Revised ROHC IP/UDP/RTP profiles submitted to IESG for
publication as Proposed Standard

Done SigComp Implementer's Guide submitted to IESG for publication
as Proposed Standard

Jan 2007 RObust Header Compression Protocol Number Registration
submitted to IESG for publication as Proposed Standard

Feb 2007 ROHC encapsulation profile(s) for IPHC/CRTP/eCRTP submitted to
IESG for publication as Proposed Standard

Mar 2007 IKE/IPsec extensions for HC-session Parameter Negotiation
submitted to IESG for publication as Proposed Standard

Mar 2007 Header Compression over IPsec (HCoIPsec) submitted to IESG for
publication as Informational

Jun 2007 Recharter of WG to develop additional profiles if needed, or
possible additional compression schemes. Consideration of
concluding the working group.

Internet-Drafts:

Posted Revised I-D Title <Filename>
------ ------- --------------------------------------------
Nov 2005 Feb 2009 <draft-ietf-rohc-hcoipsec-10.txt>
Integration of Robust Header Compression (ROHC) over IPsec
Security Associations

Sep 2006 Feb 2009 <draft-ietf-rohc-ikev2-extensions-hcoipsec-08.txt>
IKEv2 Extensions to Support Robust Header Compression over
IPsec (ROHCoIPsec)

Aug 2007 Feb 2009 <draft-ietf-rohc-ipsec-extensions-hcoipsec-04.txt>
IPsec Extensions to Support Robust Header Compression over
IPsec (ROHCoIPsec)

Aug 2008 Aug 2008 <draft-ietf-rohc-rfc4995bis-00.txt>
The RObust Header Compression (ROHC) Framework

Request For Comments:

RFC Stat Published Title
------- -- ----------- ------------------------------------
RFC3095 PS Jul 2001 RObust Header Compression (ROHC)

RFC3096 I Jul 2001 Requirements for robust IP/UDP/RTP header compression

RFC3242 PS May 2002 A Link-Layer Assisted ROHC Profile for IP/UDP/RTP

RFC3243 I May 2002 Requirements and assumptions for ROHC 0-byte IP/UDP/RTP
compression

RFC3241 PS May 2002 ROHC over PPP

RFC3408 PS Dec 2002 Zero-byte Support for Reliable Bidirectional Mode
(R-mode) in Extended Link-Layer Assisted RObust Header
Compression (ROHC) Profile

RFC3409 I Dec 2002 Lower Layer Guidelines for Robust RTP/UDP/IP Header
Compression

RFC3321 I Jan 2003 SigComp - Extended Operations

RFC3320 PS Jan 2003 Signaling Compression

RFC3322 I Jan 2003 Signaling Compression Requirements & Assumptions

RFC3759 I Apr 2004 RObust Header Compression (ROHC):Terminology and Channel
Mapping Examples

RFC3816Standard Jun 2004 Definitions of Managed Objects for Robus Header
Compression

RFC3843Standard Jul 2004 RObust Header Compression (ROHC): A Compression Profile
for IP

RFC4019Standard Apr 2005 RObust Header Compression (ROHC):Profiles for UDP-Lite

RFC4077Standard May 2005 A Negative Acknowledgement Mechanism for Signaling
Compression

RFC4163 I Aug 2005 RObust Header Compression (ROHC): Requirements on TCP/IP
Header Compression

RFC4164Standard Sep 2005 RObust Header Compression (ROHC):Context Replication for
ROHC Profiles

RFC4224 I Jan 2006 RObust Header Compression (ROHC): ROHC over Channels
that can Reorder Packets

RFC4362Standard Jan 2006 RObust Header Compression (ROHC): A Link-Layer Assisted
Profile for IP/UDP/RTP

RFC4413 I Mar 2006 TCP/IP Field Behavior

RFC4464 I May 2006 Signaling Compression (SigComp) Users' Guide

RFC4465 I Jun 2006 Signaling Compression (SigComp) Torture Tests

RFC4815 PS Feb 2007 RObust Header Compression (ROHC): Corrections and
Clarifications to RFC 3095

RFC4896 PS Jun 2007 Signaling Compression (SigComp) Corrections and
Clarifications

RFC4997 PS Jul 2007 Formal Notation for RObust Header Compression (ROHC-FN)

RFC4996 PS Jul 2007 RObust Header Compression (ROHC): A Profile for TCP/IP
(ROHC-TCP)

RFC4995 PS Jul 2007 The RObust Header Compression (ROHC) Framework

RFC5049 PS Dec 2007 Applying Signaling Compression (SigComp) to the Session
Initiation Protocol (SIP)

RFC5225 PS Apr 2008 RObust Header Compression Version 2 (ROHCv2): Profiles
for RTP, UDP, IP, ESP and UDP Lite