Data Center TCP (DCTCP): TCP Congestion Control for Data Centers
RFC 8257
| Document | Type |
RFC - Informational
(October 2017; No errata)
Was draft-ietf-tcpm-dctcp (tcpm WG)
|
|
|---|---|---|---|
| Last updated | 2017-10-17 | ||
| Replaces | draft-bensley-tcpm-dctcp | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Michael Scharf | ||
| Shepherd write-up | Show (last changed 2017-04-20) | ||
| IESG | IESG state | RFC 8257 (Informational) | |
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Mirja Kühlewind | ||
| Send notices to | "Michael Scharf" <michael.scharf@nokia.com> | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | No IANA Actions | ||
Internet Engineering Task Force (IETF) S. Bensley
Request for Comments: 8257 D. Thaler
Category: Informational P. Balasubramanian
ISSN: 2070-1721 Microsoft
L. Eggert
NetApp
G. Judd
Morgan Stanley
October 2017
Data Center TCP (DCTCP): TCP Congestion Control for Data Centers
Abstract
This Informational RFC describes Data Center TCP (DCTCP): a TCP
congestion control scheme for data-center traffic. DCTCP extends the
Explicit Congestion Notification (ECN) processing to estimate the
fraction of bytes that encounter congestion rather than simply
detecting that some congestion has occurred. DCTCP then scales the
TCP congestion window based on this estimate. This method achieves
high-burst tolerance, low latency, and high throughput with shallow-
buffered switches. This memo also discusses deployment issues
related to the coexistence of DCTCP and conventional TCP, discusses
the lack of a negotiating mechanism between sender and receiver, and
presents some possible mitigations. This memo documents DCTCP as
currently implemented by several major operating systems. DCTCP, as
described in this specification, is applicable to deployments in
controlled environments like data centers, but it must not be
deployed over the public Internet without additional measures.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8257.
Bensley, et al. Informational [Page 1]
RFC 8257 DCTCP October 2017
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. DCTCP Algorithm . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Marking Congestion on the L3 Switches and Routers . . . . 5
3.2. Echoing Congestion Information on the Receiver . . . . . 5
3.3. Processing Echoed Congestion Indications on the Sender . 7
3.4. Handling of Congestion Window Growth . . . . . . . . . . 8
3.5. Handling of Packet Loss . . . . . . . . . . . . . . . . . 8
3.6. Handling of SYN, SYN-ACK, and RST Packets . . . . . . . . 9
4. Implementation Issues . . . . . . . . . . . . . . . . . . . . 9
4.1. Configuration of DCTCP . . . . . . . . . . . . . . . . . 9
4.2. Computation of DCTCP.Alpha . . . . . . . . . . . . . . . 10
5. Deployment Issues . . . . . . . . . . . . . . . . . . . . . . 11
6. Known Issues . . . . . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . 14
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
Bensley, et al. Informational [Page 2]
RFC 8257 DCTCP October 2017
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