Datagram Congestion Control Protocol (DCCP)
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From: The IESG <email@example.com> To: IETF-Announce <firstname.lastname@example.org> Cc: Internet Architecture Board <email@example.com>, RFC Editor <firstname.lastname@example.org>, dccp mailing list <email@example.com>, dccp chair <firstname.lastname@example.org> Subject: Protocol Action: 'Datagram Congestion Control Protocol (DCCP)' to Proposed Standard The IESG has approved the following document: - 'Datagram Congestion Control Protocol (DCCP) ' <draft-ietf-dccp-spec-14.txt> as a Proposed Standard This document is the product of the Datagram Congestion Control Protocol Working Group. The IESG contact persons are Allison Mankin and Magnus Westerlund. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-dccp-spec-14.txt
*Â Â Technical Summary The Datagram Congestion Control Protocol (DCCP) is a transport protocol that provides bidirectional unicast connections of congestion-controlled unreliable datagrams.Â DCCP is suitable for applications that transfer fairly large amounts of data, but can benefit from control over the tradeoff between timeliness and reliability.Â TCP is not well-suited for these applications, since reliable in-order delivery and congestion control can cause arbitrarily long delays.Â UDP avoids long delays, but UDP applications that implement congestion control must do so on their own.Â DCCP provides built-in congestion control, including ECN support, for unreliable datagram flows, avoiding the arbitrary delays associated with TCP.Â It also implements mechanisms for reporting loss, reliable connection setup, teardown, and feature negotiation.Â The congestion control mechanisms are defined in Congestion Control Profile documents, known as CCIDs. Â Â Â Â *Â Â Working Group Summary There is a strong working group consensus to develop this protocol. The applicability of DCCP to interactive real-time multimedia flows has been somewhat controversial in the working group. The DCCP protocol specification has been developed with just two initial congestion control profiles, companions to this publication, draft-ietf-dccp-ccid2, and draft-ietf-dccp-ccid3. However, the modular nature of the protocol enables the core specification to be completed while work proceeds on congestion control profiles for interactive real-time applications. There is clear and strong support for applying DCCP to non-realtime streaming and growing interest in other applications as well. Â Â Â Â *Â Â Protocol Quality DCCP has received extensive transport and cross-disciplinary review. Written "expert reviews" were conducted by Eric Rescorla (a security expert), Magnus Westerlund (a multimedia expert and AVT wg chair), and Greg Minshall (a TCP expert), generating many detailed comments and substantive improvements in the protocol.Â The expert review was followed by a working group "design review" at IETF-57 where the working group and invited experts -- Magnus Westerlund (multimedia), Steve Bellovin (security), and Rob Austein (architecture) -- walked through the spec in detail resulting in additional comments and substantive changes.Â Additionally, formal modeling was performed showing that DCCP is deadlock-free.Â The protocol is as mature as is possible without significant implementation experience.Â The three known implementations were started early in the life of the specification and one (from ICIR) resulted in some relatively major changes to the spec.Â Recently, it has become known that Kame FreeBSD contains an implementation of DCCP, albeit not matching the final version of the spec.Â It is expected that feedback from implementors and users will result in further improvements and revisions. The IESG review of the specification was done by Allison Mankin. The WG Chair shepherd was Aaron Falk.