Editing Explicit Congestion Notification (section)

=== {{Anchor|DCTCP}}Data Center TCP ===
''Data Center Transmission Control Protocol'' (''Data Center TCP'' or ''DCTCP'') utilizes ECN to enhance the [[Transmission Control Protocol]] congestion control algorithm.<ref>{{cite web|title=Data Center TCP (DCTCP)|url=http://netbsd.org/releases/formal-4/NetBSD-4.0.html|archive-url=https://web.archive.org/web/20141031073922/http://netbsd.org/releases/formal-4/NetBSD-4.0.html |access-date=March 7, 2023|archive-date=2014-10-31 }}</ref> It is used in [[data center]] networks. Whereas the standard [[TCP congestion control algorithm]] is only able to detect the ''presence'' of congestion, DCTCP, using ECN, is able to gauge the ''extent'' of congestion.<ref>{{cite IETF|rfc=8257|title=Data Center TCP (DCTCP): TCP Congestion Control for Data Centers|access-date=August 21, 2021}}</ref>

DCTCP modifies the TCP receiver to always relay the exact ECN marking of incoming packets at the cost of ignoring a function that is meant to preserve signalling reliability. This makes a DCTCP sender vulnerable to loss of ACKs from the receiver, which it has no mechanism to detect or cope with.<ref name="rfc7560">{{Cite IETF |rfc = 7560 |title = Problem Statement and Requirements for Increased Accuracy in Explicit Congestion Notification (ECN) Feedback |date = August 26, 2015 |access-date = August 21, 2021}}</ref> {{As of|2014|7}}, algorithms that provide equivalent or better receiver feedback in a more reliable approach are an active research topic.<ref name="rfc7560"/>