Evaluation of Different Decrease Schemes for LEDBAT Congestion Control
Low Extra Delay Background Transport (LEDBAT) is a new, delay-based congestion control algorithm that is currently under development in the IETF. LEDBAT has been proposed by BitTorrent for time-insensitive background traffic that otherwise would disturb foreground traffic like VoIP or video streaming. During previous evaluations the so called late-comer advantage has been discovered which makes a new starting LEDBAT flow predominant against already running LEDBAT flows. In this paper we evaluate different decrease schemes which have been proposed to solve this problem. We found that the proposed solutions come with a lower utilization, sometimes increased completion times and are much more sensitive to noise, which is contra-productive for the considered traffic class. Furthermore, we propose extensions to both evaluated schemes. We show that our approach can help to yield more quickly to higher priority traffic. We argue that a fair and equal share is not required for the specific traffic class LEDBAT is designed for. But it is important to address different application requirements in congestion control like LEDBAT as an approach for less-than-best effort background traffic.
KeywordsCompletion Time Congestion Control Congestion Window Internet Engineer Task Force Bottleneck Link
Unable to display preview. Download preview PDF.
- 1.Schulze, H., Mochalski, K.: Internet study 2008/2009. IPOQUE Report (2009)Google Scholar
- 2.Shalunov: S., Hazel, G., Iyengar, J., Kuehlewind, M.: Low extra delay background transport (LEDBAT). draft-ietf-ledbat-congestion-06 (2011)Google Scholar
- 3.Carofiglio, G., Muscariello, L., Rossi, D., Valenti, S.: The quest for LEDBAT fairness. In: IEEE Globecom (December 2010)Google Scholar
- 5.Carofiglio, G., Muscariello, L., Rossi, D., Testa, C.: A hands-on assessment of transport protocols with lower than best effort priority. In: 35th IEEE Conference on Local Computer Networks, LCN 2010 (October 2010)Google Scholar
- 6.Rossi, D., Testa, C., Valenti, S., Muscariello, L.: LEDBAT: the new BitTorrent congestion control protocol. In: International Conference on Computer Communication Networks, ICCCN 2010 (August 2010)Google Scholar
- 7.Briscoe, B.: A fairer, faster internet protocol. IEEE Spectrum, 38–43 (2008)Google Scholar
- 8.Schneider, J., Wagner, J., Winter, R., Kolbe, H.: Out of my Way Evaluating Low Extra Delay Background Transport in an ADSL Access Network. In: Proceedings of the 22nd International Teletraffic Congress (ITC22), pp. 7–9 (2010)Google Scholar
- 9.IKR Simulation and Emulation Library, http://www.ikr.uni-stuttgart.de/content/ikrsimlib/
- 10.Jansen, S., McGregor, A.: Simulation with Real World Network Stacks. In: Proc. Winter Simulation Conference, pp. 2454–2463 (September 2005)Google Scholar
- 11.Allman, M., Paxson, V., Blanton, E.: TCP Congestion Control. RFC 5681 (2009)Google Scholar