Datagram Congestion Control Protocol (DCCP)
Abstract
Fast-growing Internet applications like streaming media and telephony prefer timeliness to reliability, making TCP a poor fit. Unfortunately, UDP, the natural alternative, lacks con- gestion control. High-bandwidth UDP applications must im- plement congestion control themselvesa difficult taskor risk rendering congested networks unusable. We set out to ease the safe deploymentofthese applicationsbydesigninga congestion-controlledunreliable transport protocol. The out- come, the Datagram Congestion Control Protocol or DCCP, addstoaUDP-likefoundationtheminimummechanismsnec- essarytosupportcongestioncontrol.We thoughtthosemech- anismswouldresembleTCP„¢s,butwithoutreliabilityand,es- pecially,cumulativeacknowledgements,wehadtoreconsider almost every aspect of TCP„¢s design. The resulting protocol sheds light on how congestion control interacts with unreli- abletransport,howmodernnetworkconstraintsimpactproto- col design, and how TCP„¢s reliable bytestream semantics in- tertwinewithitsothermechanisms,includingcongestioncon- trol