Research : Congestion Control
Explicit Congestion Notification and the RTP circuit breaker
12 June 2016 / cc
How should the RTP circuit breaker react to persistent excessive congestion signalled via ECN? Indeed, should the circuit breaker react to such a congestion signal?
Omniscient TCP for congestion control in data centre networks
25 April 2016 / cc
Simon Jouet presented his work on OTCP: SDN-Managed Congestion Control for Data Centre Networks at the IEEE/IFIP Network Operations and Management Symposium workshop in Istanbul, Turkey, in April 2016. OTCP is an OpenFlow-based approach to tuning TCP congestion control parameters to better match network characteristics that can improve flow completion times in data centre networks.
Media usability circuit breakers for RTP-based interactive networked multimedia
30 September 2015 / cc
Our paper on Media usability circuit breakers for RTP-based interactive networked multimedia was presented at the 21st International Packet Video workshop in Cairns, Australia, on 2 June 2015.
An Evaluation of RTP Circuit Breaker Performance on LTE Networks
15 February 2014 / cc
Our paper on An Evaluation of RTP Circuit Breaker Performance on LTE Networks will be presented in the IEEE Infocom Workshop on Communication and Networking Techniques for Contemporary Video in Toronto, Canada, in April 2014.
Circuit Breakers for Multimedia Congestion Control
16 December 2013 / cc
Our paper on Circuit Breakers for Multimedia Congestion Control was presented at the 20th International Packet Video workshop in San Jose, CA, USA, on 12 December 2013.
IETF 86 — RTCP Feedback for Unicast Multimedia Congestion Control
11 March 2013 / cc
I submitted a draft on the use of RTCP Feedback for Unicast Multimedia Congestion Control. Congestion control requires a feedback loop, to report on reception quality, and in the case of RTP-based multimedia, this is has typically been provided by RTCP feedback. There have been some suggestions in the working group that RTCP feedback is too slow for effective congestion control. This draft provides a rough sketch of how quickly feedback can be provided by RTCP. It seems clear that per-packet feedback cannot be provided using RTCP, but per-frame feedback is very possible. If RTCP is to be used in it's current form for congestion feedback, then the algorithms should be designed to work with feedback per-frame or per-RTT, rather than per packet.
Can Congestion-controlled Interactive Multimedia Traffic Co-exist with TCP?
11 December 2012 / cc
I gave an invited talk on “Can Congestion-controlled Interactive Multimedia Traffic Co-exist with TCP?” in the Capacity Sharing Workshop at ACM CoNEXT 2012 in Nice, France, yesterday. The abstract for my talk was: “The WebRTC activity in the Internet Engineering Task Force (IETF) and World-Wide Web Consortium (W3C) is adding standards-based interactive multimedia conferencing features to web browsers. WebRTC systems are expected to see extremely wide deployment, starting in the next year. This deployment poses a challenge, since congestion control algorithms for interactive multimedia have not been standardized. The nature of interactive multimedia traffic complicates congestion control, and the interactions between WebRTC traffic, TCP flows, and the modern network worsen the problem. The region where congestion-controlled interactive multimedia traffic can feasibly co-exist with TCP is outlined, and areas where additional development seems necessary are highlighted.”
IETF 84 — RTP Media Congestion Avoidance Techniques BoF
8 August 2012 / cc
RTP Congestion Control: Circuit Breakers for Unicast Sessions (-01)
17 July 2012 / cc
We've just submitted an updated version of the RTP circuit breakers draft. This is a minor update, to address the comments from our presentations at IETF 83 in Paris earlier this year. The main change in this version is to use the simple TCP throughput model of Mathis et al in place of the more complex model used in the earlier version of the draft. There have also been various minor editorial clarifications and corrections.
IETF 83 — RTP Circuit Breakers Presentations
27 March 2012 / cc
I gave a presentation about the RTP Circuit Breakers draft to the IRTF ICCRG, meeting in Paris in March 2012. The presentation was generally well-received. The main conclusion from the discussion following the presentations was that the simple TCP throughput model of Mathis et al is sufficient for this purpose, and there is little need to use the more complex model of Padhye et al. An updated version of the draft will be submitted in a few weeks to address this, and other, feedback.
IETF 83 — TCP Segment Caching Presentation
27 March 2012 / cc
TCP Segment Caching
8 March 2012 / cc
This internet-draft describes Content- and Cache-Aware TCP (CATCP). This is an extension to TCP that allows caching of TCP segments, so they can be re-used between different flows transmitting same data. When large amounts of redundant data are being simultaneously sent to multiple receivers, this can lead to significant load reductions and performance improvements. A typical use-case might be to improve the efficiency of HTTP-based streaming video services, through ubiquitous in-network caching.
Alvaro Saurin — Congestion Control for Video-conferencing Applications
15 December 2006 / cc
Congratulations to Alvaro Saurin, who has completed his MSc thesis on Congestion Control for Video-conferencing Applications, looking into how well TCP-Friendly Rate Control (TFRC) works on real-world networks.
Experiences with Interactive Video Using TFRC
12 July 2006 / cc
I gave a presentation on our experiences with interactive video using TFRC to the Datagram Congestion Control Protocol (DCCP) working group at the 66th IETF meeting in Montreal, Canada, on 12 July 2006.
New research student: Alvaro Saurin
1 December 2004 / cc
Welcome to Alvaro Saurin, who will be working on integration of TCP Friendly Rate Control (TFRC) with high performance interactive video, as part of the UltraGrid project.
Congestion Control for Real-Time Media
13 February 2002 / cc
Provision of congestion control is a significant open issue for interactive real-time networked multimedia systems. Numerous congestion control algorithms have been proposed, but they frequently conflict with the demands of interactive multimedia applications. My paper “Building Adaptive Applications: On The Need For Congestion Control” (an invited paper presented at the 17th SPIE/IS&T International Symposium on Electronic Imaging, San Jose, CA, USA, January 2005) outlines some of the issues.