DRED: A random early detection algorithm for TCP/IP networks

James Aweya, Michel Ouellette, Delfin Y. Montuno

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


It is now widely accepted that a RED controlled queue certainly performs better than a drop-tail queue. But an inherent weakness of RED is that its equilibrium queue length cannot be maintained at a preset value independent of the number of TCP active connections. In addition, RED's optimal parameter setting is largely correlated with the number of connections, the round-trip time, the buffer space, etc. In light of these observations, we propose DRED, a novel algorithm which uses the basic ideas of feedback control to randomly discard packets with a load-dependent probability when a buffer in a router gets congested. Over a wide range of load levels, DRED is able to stabilize a router queue occupancy at a level independent of the number of active TCP connections. The benefits of stabilized queues in a network are high resources utilization, predictable maximum delays, more certain buffer provisioning, and traffic-load-independent network performance in terms of traffic intensity and number of connections.

Original languageBritish English
Pages (from-to)287-307
Number of pages21
JournalInternational Journal of Communication Systems
Issue number4
StatePublished - May 2002


  • Active queue management
  • Congestion control
  • Control theory
  • Random early detection
  • TCP


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