--- 1/draft-ietf-6man-exthdr-03.txt 2011-07-12 00:15:48.000000000 +0200 +++ 2/draft-ietf-6man-exthdr-04.txt 2011-07-12 00:15:48.000000000 +0200 @@ -1,50 +1,53 @@ 6man Working Group S. Krishnan Internet-Draft Ericsson Intended status: Standards Track j h. woodyatt -Expires: December 29, 2011 Apple +Expires: January 12, 2012 Apple E. Kline Google J. Hoagland Symantec M. Bhatia Alcatel-Lucent - June 27, 2011 + July 11, 2011 An uniform format for IPv6 extension headers - draft-ietf-6man-exthdr-03 + draft-ietf-6man-exthdr-04 Abstract In IPv6, optional internet-layer information is encoded in separate headers that may be placed between the IPv6 header and the transport layer header. There are a small number of such extension headers - currently defined. This document defines a format for defining new - IPv6 extension headers. + currently defined. This document describes the issues that can arise + when defining new extension headers and discusses the alternative + extension mechanisms in IPv6. It also provides a format for defining + new IPv6 extension headers that would allow implementations to + process past unknown extension headers. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on December 29, 2011. + This Internet-Draft will expire on January 12, 2012. 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 @@ -53,27 +56,27 @@ 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. Conventions used in this document . . . . . . . . . . . . . . . 3 3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Proposed IPv6 Extension Header format . . . . . . . . . . . . . 5 - 5. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 6 - 6. Future work . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 - 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 - 10. Normative References . . . . . . . . . . . . . . . . . . . . . 7 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 + 5. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 5 + 6. Future work . . . . . . . . . . . . . . . . . . . . . . . . . . 5 + 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 + 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 + 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 + 10. Normative References . . . . . . . . . . . . . . . . . . . . . 6 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction The base IPv6 standard [RFC2460] defines extension headers as an expansion mechanism to carry optional internet layer information. Extension headers, with the exception of the hop-by-hop options header, are not usually processed on intermediate nodes. However, some intermediate nodes such as firewalls, may need to look at the transport layer header fields in order to make a decision to allow or deny the packet. If new extension headers are defined and the @@ -147,24 +150,26 @@ Mindful of the need for compatibility with existing IPv6 deployments, new IPv6 extension headers MUST NOT be created or specified, unless no existing IPv6 Extension Header can be used by specifying a new option for that existing IPv6 Extension Header. Any proposal to create or specify a new IPv6 Extension Header MUST include a detailed technical explanation of why no existing IPv6 Extension Header can be used in the Internet-Draft proposing the new IPv6 Extension Header. 4. Proposed IPv6 Extension Header format - This document proposes that all IPv6 extension headers be encoded in - a consistent format so that it is possible for nodes to skip over - unknown extension headers and continue to further process the header - chain. + If any IPv6 Extension Headers are defined in future, keeping in mind + the restrictions specified in Section 3 and also the restrictions + specified in [RFC2460], they MUST use the consistent format defined + in Figure 1. This enables future IPv6 implementations to skip over + unknown IPv6 Extension Headers and continue to further process the + IPv6 header chain. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Header | Hdr Ext Len | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | | . . . Header Specific Data . . . @@ -215,22 +219,22 @@ such as firewalls, skipping over unknown headers might end up allowing the setup of a covert channel from the outside of the firewall to the inside using the data field(s) of the unknown extension headers. 9. Acknowledgements The authors would like to thank Albert Manfredi, Bob Hinden, Brian Carpenter, Erik Nordmark, Hemant Singh, Lars Westberg, Markku Savela, Tatuya Jinmei, Thomas Narten, Vishwas Manral, Alfred Hoenes, Joel - Halpern and Ran Atkinson for their reviews and suggestions that made - this document better. + Halpern, Ran Atkinson and Steven Blake for their reviews and + suggestions that made this document better. 10. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. Authors' Addresses