Encoding Three Pre-Congestion Notification (PCN) States in the IP Header Using a Single Diffserv Codepoint (DSCP)
RFC 6660
Document | Type |
RFC - Proposed Standard
(July 2012; No errata)
Obsoletes RFC 5696
|
|
---|---|---|---|
Authors | Bob Briscoe , Toby Moncaster , Michael Menth | ||
Last updated | 2018-12-20 | ||
Replaces | draft-briscoe-pcn-3-in-1-encoding | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | WG Document | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6660 (Proposed Standard) | |
Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | Martin Stiemerling | ||
IESG note | Scott Bradner (sob@harvard.edu) is the document shephed. | ||
Send notices to | (None) |
Internet Engineering Task Force (IETF) B. Briscoe Request for Comments: 6660 BT Obsoletes: 5696 T. Moncaster Category: Standards Track University of Cambridge ISSN: 2070-1721 M. Menth University of Tuebingen July 2012 Encoding Three Pre-Congestion Notification (PCN) States in the IP Header Using a Single Diffserv Codepoint (DSCP) Abstract The objective of Pre-Congestion Notification (PCN) is to protect the quality of service (QoS) of inelastic flows within a Diffserv domain. The overall rate of PCN-traffic is metered on every link in the PCN- domain, and PCN-packets are appropriately marked when certain configured rates are exceeded. Egress nodes pass information about these PCN-marks to Decision Points that then decide whether to admit or block new flow requests or to terminate some already admitted flows during serious pre-congestion. This document specifies how PCN-marks are to be encoded into the IP header by reusing the Explicit Congestion Notification (ECN) codepoints within a PCN-domain. The PCN wire protocol for non-IP protocol headers will need to be defined elsewhere. Nonetheless, this document clarifies the PCN encoding for MPLS in an informational appendix. The encoding for IP provides for up to three different PCN marking states using a single Diffserv codepoint (DSCP): not-marked (NM), threshold-marked (ThM), and excess-traffic-marked (ETM). Hence, it is called the 3-in-1 PCN encoding. This document obsoletes RFC 5696. Status of This Memo This is an Internet Standards Track document. 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). Further information on Internet Standards is available in 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/rfc6660. Briscoe, et al. Standards Track [Page 1] RFC 6660 3-in-1 PCN Encoding July 2012 Copyright Notice Copyright (c) 2012 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. Definitions and Abbreviations . . . . . . . . . . . . . . . . 4 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. List of Abbreviations . . . . . . . . . . . . . . . . . . 5 3. Definition of 3-in-1 PCN Encoding . . . . . . . . . . . . . . 6 4. Requirements for and Applicability of 3-in-1 PCN Encoding . . 7 4.1. PCN Requirements . . . . . . . . . . . . . . . . . . . . . 7 4.2. Requirements Imposed by Tunnelling . . . . . . . . . . . . 7 4.3. Applicable Environments for the 3-in-1 PCN Encoding . . . 8 5. Behaviour of a PCN-node to Comply with the 3-in-1 PCN Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. PCN-Ingress-Node Behaviour . . . . . . . . . . . . . . . . 8 5.2. PCN-Interior-Node Behaviour . . . . . . . . . . . . . . . 11 5.2.1. Behaviour Common to All PCN-Interior-Nodes . . . . . . 11 5.2.2. Behaviour of PCN-Interior-Nodes Using Two PCN-Markings . . . . . . . . . . . . . . . . . . . . . 11 5.2.3. Behaviour of PCN-Interior-Nodes Using One PCN-Marking . . . . . . . . . . . . . . . . . . . . . 12 5.3. PCN-Egress-Node Behaviour . . . . . . . . . . . . . . . . 13 6. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 13 6.1. Backward Compatibility with ECN . . . . . . . . . . . . . 13 6.2. Backward Compatibility with the Encoding in RFC 5696 . . . 14 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 15Show full document text