Robust Header Compression (rohc) -------------------------------- Charter Last Modified: 2007-09-28 Current Status: Active Working Group Chair(s): Carl Knutsson Transport Area Director(s): Magnus Westerlund Lars Eggert Transport Area Advisor: Magnus Westerlund Technical Advisor(s): Erik Nordmark Carsten Bormann 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 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: No Current Internet-Drafts. 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