Datagram Congestion Control Protocol (DCCP)

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 themselves a difficult task or risk rendering congested networks unusable. We set out to ease the safe deployment of these applications by designing a congestion-controlledunreliable transport protocol. The out- come, the Datagram Congestion Control Protocol or DCCP, addstoaUDP-like foundation the minimum mechanisms necessary to support congestion control.We thought those mechanisms would resembleTCPs,but without reliability and,especially,cumulative acknowledgements,we had to reconsider almost every aspect of TCPs design. The resulting protocol sheds light on how congestion control interacts with unreliable transport, how modern network constraints impact protocol design, and how TCPs reliable byte stream semantics intert wine with it so thermechanisms,including congestion control.