GridNet2 Trip Report: SUMOVER Workshop
28-30 November 2005
London
Dr. Colin Perkins
University of Glasgow
GridNet ID 96
2 January 2006
I attended the SUMOVER workship in London, 28-30 November 2005, funded by a GridNet2 award. This brief report
summarises the discussion and outcomes of my trip, in accordance with GridNet2 requirements.
The SUMOVER project is a JISC-funded development activity at University College London (UCL) that aims to provide
for support and development of the Mbone Videoconferencing tools for the research community. It is a follow-on to the
early development work at UCL that produced the Robust Audio Tool (rat) and continued development of the vic video
conferencing system, the tools which underpin the AccessGrid virtual collaborative environment.
I was invited to attend the SUMOVER workshop for several reasons: 1) several years ago I was one of the original
developers of rat, and have extensive experience with that system; 2) my research into HDTV over IP and congestion
controlled and peer-to-peer algorithms for video conferencing is directly relevant to SUMOVER; and 3) I co-chair the
IETF Audio/Video Transport (AVT) and Multiparty Multimedia Session Control (MMUSIC) working groups which
develop related standards. It is for this final reason that GridNet2 funded my attendance at this workshop.
My participation in the SUMOVER workshop was two-fold: I discussed my research results where relevant to the aims of
SUMOVER; and I discussed how new developments in the IETF community might impact the development of the
AccessGrid and hence the tools maintained by the SUMOVER project. The developments in the IETF that may be
relevant include:
•
Continued development of SIP-based solutions for session initiation and control, using the SDP offer/answer model
for media negotiation.
•
A heavy push for NAT traversal solutions, such as the ICE methodology being developed in the IETF MMUSIC
working group.
•
Development of new RTP profiles for security and to provide improved feedback for reception quality monitoring and
codec control.
•
Development of new RTP payload formats for iLBC, AMR, H.264 and their variants.
•
Development of new congestion controlled transport protocols for audio/visual media (e.g. the RTP profile for TFRC,
and DCCP).
•
Continued push to deprecate traditional IP multicast and replace it with a Source Specific Multicast system; work on
QoS; peer-to-peer algorithms; E911.
I am author of the updated SDP specification and the new specification for RTP over DCCP, and the SUMOVER
workshop offered an invaluable opportunity to socialise this specification prior to its adoption by the IETF. It also
provided a valuable opportunity for me to seek input from the open source and academic/e-science communities on their
priorities, which can feed into the IETF through my position as working group chair.