GridNet2 Trip Report: 66th IETF Meeting
Dr. Colin Perkins
University of Glasgow
25 July 2006
I attended the 66th IETF meeting in Montréal, 10-14 July 2006, funded by a GridNet2 award. This brief report
summarises the discussion and outcomes of my trip, in accordance with GridNet2 requirements. GridNet2 is funding
my continued activities as co-chair of the Audio/Video Transport (AVT) and the 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 these working groups,
and my related activities, that are 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
66th IETF meeting, and conducted numerous ad-hoc meetings with document authors to discuss their work and to
help resolve open issues in a timely manner. The main areas of dicsussion in the working group are video codec
control messages (to enhance support for centralised multiparty conferences, as a robust alternative to the multicast
architecture used by the AccessGrid), the definition of the RTP Payload Format and signalling for the H.264 scalable
video coding (SVC) extensions, to support extremely large scale heterogenous conferencing sessions, and improved
diagnostic and management tools.
The MMUSIC working group develops protocol standards for initiation and control of real-time sessions. The
major current work item in MMUSIC is the Interactive Connectivity Establishment (ICE) methodology for NAT
traversal, which is needed to allow 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 NAT traversal for file transfer, RPC, and other signalled sessions.
As such, the underlying technology can be used by Grid Computing and Peer-to-peer applications, as well as by
voice-over-IP and video conferencing systems. I chaired the MMUSIC session at the 66th IETF meeting, managing
discussion of these issues.
There is also considerable ongoing work in the IETF to enhance the security of voice-over-IP and other video
conferencing systems. I am closely engaged with this work, to ensure the resulting standards sit well with the RTP
protocol architecture, and do not ignore the needs of the large scale conferencing and e-science communities (both
of which are, sadly, under represented in the IETF). This is taking place in the ’RTPSEC’ BOF and mailing list.
In addition to my work chairing these working groups, I contribute to the Datagram Congestion Control Protocol
(DCCP) working group. DCCP is a new protocol that is of wide interest in the e-science community since it
allows for a range of congestion control responses, making it better suited to the needs of large scale streaming
data applications than TCP or UDP. I presented an update to the specification for transport of RTP-over-DCCP,
which was accepted as a work item of the DCCP group at this past meeting, and will form the basis for future video
streaming and visualisation systems, and also bulk real-time data (e.g. sensor or e-VLBI) streaming. I also presented
preliminary results to show performance of applications using TFRC Friendly Rate Control (as used in DCCP CCID
4) when running over real-world networks. This latter presentation was well received by the community of DCCP
implementors.