The IESG has approved the Internet-Draft 'A Link-Layer Assisted ROHC
Profile for IP/UDP/RTP' <draft-ietf-rohc-rtp-lla-03.txt> as a Proposed
Standard.
In the same action, the IESG approved publication of Requirements and
assumptions for ROHC 0-byte IP/UDP/RTP compression
<draft-ietf-rohc-rtp-0-byte-requirements-02.txt> as an Informational
RFC.
These documents are the product of the Robust Header Compression
Working Group. The IESG contact persons are Allison Mankin and Scott
Bradner.
Technical Summary
This document set defines a ROHC profile for compression of IP/UDP/RTP
packets that leverages functionality provided by the lower layers
by completely eliminating the header for most packets during
optimal operation. The requirements on the enabling lower layer
functionality are discussed by the 0-byte requirements document.
The motivation is not super-optimization (squeezing out that last
octet) but the adaptation of the RFC 3095 profile to existing, older
air interfaces (such as those based on GSM) in which the single octet
ROHC header pushes a packet voice stream into the next higher fixed
packet size of the link. The ROHC RTP profile (RFC 3095) allows
more flexible air interfaces to attain excellent spectrum efficiency
with RTP media, and this profile extends that result to a larger
set of deployed environments.
Working Group Summary
There was initially working group dissent about the goal of
a 0-byte header compression, but the work settled into
showing compatibility with RFC 3095 and applicability to
significant air-interfaces and traffic usages on them (the
profile is expected to see use on GPRS and CDMA2000).
Experimental implementations were reported on during the
development of the draft, from both Nokia and Ericsson.
Results of both experiment and discussion led to providing
only Unidirectional and Optimistic bidirectional types of
RFC 3095 in this spec (U-mode and O-mode) and for the
support for Reliable bidirectional (R-mode) to be separated
into its own draft.
Protocol Quality
Allison Mankin reviewed the documents for the IESG.
Coding and testing were reported throughout the
draft development, and there was extensive working group
review of the applicability as well as the protocol.
