TCP Modifications for Congestion Exposure (ConEx)
RFC 7786
Document | Type | RFC - Experimental (May 2016; No errata) | |
---|---|---|---|
Authors | Mirja Kühlewind , Richard Scheffenegger | ||
Last updated | 2016-05-13 | ||
Stream | Internet Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Suresh Krishnan | ||
Shepherd write-up | Show (last changed 2015-05-06) | ||
IESG | IESG state | RFC 7786 (Experimental) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Martin Stiemerling | ||
Send notices to | (None) | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | No IANA Actions |
Internet Engineering Task Force (IETF) M. Kuehlewind, Ed. Request for Comments: 7786 ETH Zurich Category: Experimental R. Scheffenegger ISSN: 2070-1721 NetApp, Inc. May 2016 TCP Modifications for Congestion Exposure (ConEx) Abstract Congestion Exposure (ConEx) is a mechanism by which senders inform the network about expected congestion based on congestion feedback from previous packets in the same flow. This document describes the necessary modifications to use ConEx with the Transmission Control Protocol (TCP). Status of This Memo This document is not an Internet Standards Track specification; it is published for examination, experimental implementation, and evaluation. This document defines an Experimental Protocol for the Internet community. 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 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7786. Kuehlewind & Scheffenegger Experimental [Page 1] RFC 7786 TCP Modifications for ConEx May 2016 Copyright Notice Copyright (c) 2016 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 (http://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 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 2. Sender-Side Modifications . . . . . . . . . . . . . . . . . . 4 3. Counting Congestion . . . . . . . . . . . . . . . . . . . . . 5 3.1. Loss Detection . . . . . . . . . . . . . . . . . . . . . 6 3.1.1. Without SACK Support . . . . . . . . . . . . . . . . 7 3.2. Explicit Congestion Notification (ECN) . . . . . . . . . 8 3.2.1. Accurate ECN Feedback . . . . . . . . . . . . . . . . 10 3.2.2. Classic ECN Support . . . . . . . . . . . . . . . . . 10 4. Setting the ConEx Flags . . . . . . . . . . . . . . . . . . . 11 4.1. Setting the E or the L Flag . . . . . . . . . . . . . . . 11 4.2. Setting the Credit Flag . . . . . . . . . . . . . . . . . 11 5. Loss of ConEx Information . . . . . . . . . . . . . . . . . . 14 6. Timeliness of the ConEx Signals . . . . . . . . . . . . . . . 14 7. Open Areas for Experimentation . . . . . . . . . . . . . . . 15 8. Security Considerations . . . . . . . . . . . . . . . . . . . 17 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 9.1. Normative References . . . . . . . . . . . . . . . . . . 18 9.2. Informative References . . . . . . . . . . . . . . . . . 19 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 Kuehlewind & Scheffenegger Experimental [Page 2] RFC 7786 TCP Modifications for ConEx May 2016 1. Introduction Congestion Exposure (ConEx) is a mechanism by which senders inform the network about expected congestion based on congestion feedback from previous packets in the same flow. ConEx concepts and use cases are further explained in [RFC6789]. The abstract ConEx mechanism is explained in [RFC7713]. This document describes the necessary modifications to use ConEx with the Transmission Control Protocol (TCP). The markings for ConEx signaling are defined in the ConEx Destination Option (CDO) for IPv6 [RFC7837]. Specifically, the use of four flags is defined: X (ConEx-capable), L (loss experienced), E (ECN experienced), and C (credit). ConEx signaling is based on the use of either loss or Explicit Congestion Notification (ECN) marks [RFC3168] as congestion indication. The sender collects this congestion information based onShow full document text