The IESG has approved the Internet-Draft 'Enhanced Compressed RTP (CRTP) for Links with High Delay, Packet Loss and Reordering' <draft-ietf-avt-crtp-enhance-07.txt> as a Proposed Standard. This document is the product of the Audio Video Transport Working Group. The IESG contact persons are Allison Mankin and Jon Peterson. Technical Summary This document describes a header compression scheme for point to point links with packet loss and long delays. It is based on Compressed Real-time Transport Protocol (CRTP), the IP/UDP/RTP header compression described in RFC 2508. Original CRTP does not perform well on such links: packet loss results in context corruption and due to the long delay, excessive packets are discarded before the context is repaired. To correct the behavior of CRTP over such links, a few extensions to the protocol are specified here. The extensions aim to reduce context corruption by changing the way the compressor updates the context at the decompressor: updates are repeated and include updates to full and differential context parameters. With these extensions, ECRTP performs well over links with packet loss, packet reordering and long delays. The distinction is made that ECRTP is robust for links with reordering such as tunnels and multihop, and it is also robust for cellular links with high loss but that ROHC (RFC 3095) is expected "to be the preferred compression mechanism over links where compression efficiency is important" and packet misordering is infrequent. Working Group Summary The working group supported advancement of this document. There were no Last Call concerns with the document, but Area Director comments resulted in clarifications on IPv6, Security considerations, and applicability. Protocol Quality/Review This document was reviewed for the IESG by Allison Mankin. The Transport Area seeks information about implementations of ECRTP and their performance.
