Boundedness of utility function based congestion controllers in the presence of delay

Sanjay Shakkottai, Rayadurgam Srikant, Sean Meyn

Research output: Contribution to journalConference articlepeer-review


We consider decentralized congestion control algorithms for low-loss operation of the Internet using the ECN bit. There has been much analysis of such algorithms, but with a few exceptions, these typically ignore the effect of feedback delays in the network on stability. We study a single node with many flows passing through it, with each flow (possibly) having a different round trip delay. Using a fluid model for the flows, we show that even with delays, the total data rate at the router is bounded; and this bound shows that the (peak) total rate grows linearly with increase in system size, i.e., the fraction of over-provisioning required is constant with respect to N, the number of flows in the system. Further, for typical user data rates and delays seen in the Internet today, the bound is very close to the data rate at the router without delays. Earlier results by Johari and Tan have given conditions for a linearized model of the network to be (locally) stable. We show that even when the linearized model is not stable, the nonlinear model is bounded, i.e., the total rate at the bottleneck link is bounded. Our most important conclusion is that in the regime of interest, very little over-provisioning is required at the router to have a low-loss, low-queueing-delay network.

Original languageEnglish (US)
Pages (from-to)616-621
Number of pages6
JournalProceedings of the IEEE Conference on Decision and Control
StatePublished - Jan 1 2001
Externally publishedYes
Event40th IEEE Conference on Decision and Control (CDC) - Orlando, FL, United States
Duration: Dec 4 2001Dec 7 2001

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Modeling and Simulation
  • Control and Optimization

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