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)
|
|
---|---|---|---|
Authors | Stephen Bensley , Dave Thaler , Praveen Balasubramanian , Lars Eggert , Glenn Judd | ||
Last updated | 2017-10-17 | ||
Replaces | draft-bensley-tcpm-dctcp | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized 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 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must 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 2017Show full document text