Robust Header Compression
charter-ietf-rohc-05

The Robust Header Compression (ROHC) Working Group was formed to
develop new header compression protocols, designed to suit today's and
future target link technologies. Most specifically, the ROHC protocols
were to take into account typical needs presented by various wireless
link technologies, and perform well for cellular links built using
technologies such as WCDMA, EDGE, and CDMA-2000. Protocol development
has thus focused on coping with issues such as high loss rates and long
round trip times.

The WG has specified a common compression protocol platform, the ROHC
framework, along with a number of compression protocols (profiles).
Most focus has been on compression of the Real-time Transport Protocol
(RTP) headers, but profiles have also been specified for compression of
UDP, ESP, IP-only, UDP-Lite, and TCP headers. The WG has further
produced a ROHC link integration specification for PPP, an optimized
RTP compression scheme for "0-byte compression", a ROHC MIB, as well as
various informational documents related to ROHC header compression
and/or header compression in general.

In addition to the work on header compression, the ROHC WG has also
developed the SigComp (Signaling Compression) protocol for end-to-end
compression of text-based signaling protocol messages.

The working group maintains 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.

The current aims of the working group are:

• to carry out a re-work of the ROHC framework and profiles
  specifications, hereafter referred to as the ROHCv2 project. The
  purpose of the ROHCv2 project is to generate a separate framework
  specification, not changing the framework part of the ROHC protocol, as
  well as a set of revised compression profiles. The most specific goals
  with the ROHCv2 profiles are to improve tolerance to packet reordering
  between compressor and decompressor, and to reduce the overall
  complexity of the protocol. It should be noted that the v2 profiles
  will thus not be compatible with the original (ROHCv1) profiles, which
  means less complex ROHC implementations can be realized by not
  providing support for ROHCv1 (over links not yet supporting ROHC, or by
  shifting out support for ROHCv1 in the long run). Profile support is
  agreed through the ROHC channel negotiation, which is part of the ROHC
  framework and thus not changed by ROHCv2.

• to update and correct the original profile specifications through
  publication of the "Corrections and Clarifications to RFC 3095"-
  document.

• to finalize the ROHC profile work for TCP header compression.

• to develop and/or document proper protocol solutions to apply ROHC
  over IPsec tunnels.

• to finalize the "SigComp implementer's guide" and "SigComp for SIP"
  documents.

The longer term goal of the working group is to advance all its
specifications to Draft Standard status (with an exception for the
original profiles being revised as part of the ROHCv2 activity).