I attended the 67th IETF meeting in San Diego from 5–10 November 2006, funded by a GridNet2 award. This brief report summarises the discussion and outcomes of my trip, in accordance with GridNet2 requirements. The
GridNet2 project is funding my continued activities as co-chair of the Audio/Video Transport (AVT) and Multiparty
Multimedia Session Control (MMUSIC) working groups in the IETF, and my work to improve the quality and flexibility of protocols for collaborative work and other real-time applications. This report will focus on activities in those working groups, and my related activities in the IETF, of interest to the UK e-science community. Opinions expressed herein are those of the author, and do not necessarily represent those of the IETF or its working groups.
The AVT working group develops standards for real-time audio/visual data transfer on IP networks. Those standards underpin modern voice over IP, 3G mobile telephony, and video conferencing systems, including the AccessGrid,
VRVS, and similar tools used by the e-science community. I co-chaired the AVT working group session at the 67th
IETF meeting. The main area of discussion in the working group session, and in several ad-hoc meeting, focussed on secure negotiation of encryption and authentication keys for multimedia sessions, considering the how the ZRTP and DTLS-based keying proposals can be adapted to better match the RTP architectural model. We came to general agreement that the current DTLS-based proposal is a better fit to the RTP architecture than the ZRTP proposal, and suggested several approaches by which ZRTP could be adapted.
In addition to chairing the session, I presented two pieces of work to the AVT working group. The first of these is new work on the mechanisms and signalling needed to multiplex RTP and RTCP on a single UDP port to ease NAT traversal. This was very well received, with widespread interest from the working group, and will be developed over the coming months. The second piece of work was on use of RTP with the Datagram Congestion Control Protocol
(DCCP) to help make multimedia applications adaptive to network congestion. This was presented in both AVT and the DCCP working groups, to get wide review as it nears completion. It is expected that this document will go to working group last call before the end of the year, and be completed early in 2007.
The MMUSIC working group develops protocol standards for initiation and control of real-time sessions. The group’s main work item is Interactive Connectivity Establishment (ICE) methodology for NAT traversal, allowing effective use of signalled real-time media in the presence of NAT devices. This is directly applicable to collaborative work tools, such as AccessGrid, but potentially has much wider use, since the mechanism is general enough to be used for file transfer, RPC, and other signalled sessions in the context of Grid Computing. I co-chaired the
MMUSIC session at the 67th IETF meeting, managing discussion of these issues, and was involved in several related discussions. ICE is expected to be completed in the first half of 2007, and I am closely involved in managing the publication of this standard.
In addition to my work chairing and contributing to these working groups, I participated in a meeting with Marshall
Eubanks (representing part of the eVLBI community) on how to develop effective network transport protocols for eVLBI data. This followed on from a presentation Marshall gave to the IETF Transport Area, and leveraged my past experience with transport of uncompressed high definition video, to discuss how to use RTP as a transport protocol for eVLBI streams. In the course of this meeting we identified several problems with the current proposal for eVLBI streaming, which could lead to loss of time synchronisation, and began initial discussion of alternative proposals.
Funding from GridNet2 continues to be essential for this work, and I believe the outcomes of this work will be of interest to the e-Science community, and will underpin future developments in Grid toolkits and collaborative work environments.