Survey of Proposed Use Cases for the IPv6 Flow Label
RFC 6294
Document | Type |
RFC - Informational
(June 2011; No errata)
Was draft-hu-flow-label-cases (gen)
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Authors | Qinwen Hu , Brian Carpenter | ||
Last updated | 2015-10-14 | ||
Stream | ISE | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | ISE state | (None) | |
Consensus Boilerplate | Unknown | ||
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 6294 (Informational) | |
Telechat date | |||
Responsible AD | Jari Arkko | ||
IESG note | ISE submission | ||
Send notices to | rfc-ise@rfc-editor.org |
Independent Submission Q. Hu Request for Comments: 6294 B. Carpenter Category: Informational Univ. of Auckland ISSN: 2070-1721 June 2011 Survey of Proposed Use Cases for the IPv6 Flow Label Abstract The IPv6 protocol includes a flow label in every packet header, but this field is not used in practice. This paper describes the flow label standard and discusses the implementation issues that it raises. It then describes various published proposals for using the flow label and shows that most of them are inconsistent with the standard. Methods to address this problem are briefly reviewed. We also question whether the standard should be revised. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This is a contribution to the RFC Series, independently of any other RFC stream. The RFC Editor has chosen to publish this document at its discretion and makes no statement about its value for implementation or deployment. Documents approved for publication by the RFC Editor are not 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/rfc6294. Copyright Notice Copyright (c) 2011 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. Hu & Carpenter Informational [Page 1] RFC 6294 Flow Label Use Cases June 2011 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. A Brief History of the Flow Label . . . . . . . . . . . . 2 1.2. The Flow Label and Quality of Service . . . . . . . . . . 3 2. Flow Label Definition and Issues . . . . . . . . . . . . . . . 4 2.1. Flow Label Properties . . . . . . . . . . . . . . . . . . 4 2.2. Dependency Prohibition . . . . . . . . . . . . . . . . . . 5 2.3. Other Issues . . . . . . . . . . . . . . . . . . . . . . . 5 3. Documented Proposals for the Flow Label . . . . . . . . . . . 6 3.1. Specify the Flow Label as a Pseudo-Random Value . . . . . 7 3.1.1. End-to-End QoS Provisioning . . . . . . . . . . . . . 7 3.1.2. Load-Balancing . . . . . . . . . . . . . . . . . . . . 8 3.1.3. Security Nonce . . . . . . . . . . . . . . . . . . . . 8 3.2. Specify QoS Parameters in the Flow Label . . . . . . . . . 8 3.3. Use Flow Label Hop-by-Hop to Control Switching . . . . . . 9 3.4. Diffserv Use of IPv6 Flow Label . . . . . . . . . . . . . 12 3.5. Other Uses . . . . . . . . . . . . . . . . . . . . . . . . 12 4. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5. Security Considerations . . . . . . . . . . . . . . . . . . . 14 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14 7. Informative References . . . . . . . . . . . . . . . . . . . . 14 1. Introduction IPv6 is being introduced to overcome the address shortage of the current IPv4 protocol, but it also offers a new feature, i.e., the Flow Label field in the IPv6 packet header. The flow label is not encrypted by IPsec and is present in all fragments. However, it is used very little in practice, for reasons discussed below and in [Amante11]. After a short introduction, this document summarizes the current specification of the IPv6 flow label and some open issues about its use in Section 2. Section 3 describes and analyzes various proposals that have been made for its use. Finally, Section 4 discusses the implications and attempts to draw conclusions. The Flow Label field occupies bits 12 through 31 of the IPv6 packet header. It provides a potential way to mark a packet, identify a flow, and look up the corresponding flow state. This field is always present in an IPv6 header, so a phrase such as "a packet with no flow label" refers to a packet whose Flow Label field contains 20 zero bits, i.e., a flow label whose value is zero. 1.1. A Brief History of the Flow Label The original proposal for a flow label has been attributed to Dave Clark [Deering93], who proposed that it should contain a pseudo- random value. A Flow Label field was included in the packet headerShow full document text