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Shepherd writeup

1. Summary

The document shepherd is Michael Scharf <>.

The responsible Area Director is Mirja Kuehlewind <>.

This informational memo describes Datacenter TCP (DCTCP). DCTCP is an
improvement to TCP congestion control for datacenter traffic that uses Explicit
Congestion Notification (ECN). DCTCP as described in this draft is applicable
to deployments in controlled environments like datacenters, but it must not be
deployed over the public Internet without additional measures. The document is
published to document an implementation in the Microsoft Windows Server 2012
operating system. The Linux and FreeBSD operating systems have also implemented
support for DCTCP.

Given the limitations of the existing DCTCP specification, which are discussed
in the document, the TCPM working group requests publication as informational

2. Review and Consensus

The objective of this informational memo is to document an alternative TCP
congestion control algorithm that is known to be widely deployed. It is
consensus in the TCPM working group that a DCTCP standard would require further
work. A precise documentation of running code enables follow-up experimental or
standards track RFCs.

The document describes DCTCP as implemented in Microsoft Windows Server 2012.
Since the publication of the first versions of the document, the Linux and
FreeBSD operating systems have also implemented support for DCTCP. The
specification should also enable implementation in other TCP stacks.

The TCPM working group has reviewed the document regarding clarity and
comprehensiveness of the protocol specification, e.g. in corner cases. The
document has been discussed multiple times in the working group without any
major controversy. During the working group last call there have been several
detailed reviews, and those comments have been addressed in the most recent
version. All in all, there is very strong consensus in the TCPM working group
that this document should be published.

3. Intellectual Property

Each author has stated that their direct, personal knowledge of any IPR related
to this document has already been disclosed, in conformance with BCPs 78 and 79.

There is an IPR disclosure for the DCTCP protocol specification
(, which declares "Royalty-Free,
Reasonable and Non-Discriminatory License to All Implementers". The TCPM
working group is aware of this IPR but there have never been concerns.

4. Other Points