--- 1/draft-ietf-6man-exthdr-02.txt 2011-06-27 20:15:54.000000000 +0200 +++ 2/draft-ietf-6man-exthdr-03.txt 2011-06-27 20:15:54.000000000 +0200 @@ -1,25 +1,25 @@ 6man Working Group S. Krishnan Internet-Draft Ericsson Intended status: Standards Track j h. woodyatt -Expires: September 15, 2011 Apple +Expires: December 29, 2011 Apple E. Kline Google J. Hoagland Symantec M. Bhatia Alcatel-Lucent - March 14, 2011 + June 27, 2011 An uniform format for IPv6 extension headers - draft-ietf-6man-exthdr-02 + draft-ietf-6man-exthdr-03 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. Status of this Memo @@ -30,21 +30,21 @@ 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 September 15, 2011. + This Internet-Draft will expire on December 29, 2011. 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 @@ -52,45 +52,62 @@ 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. Conventions used in this document . . . . . . . . . . . . . . . 3 3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 4. Proposed IPv6 Extension Header format . . . . . . . . . . . . . 4 - 5. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 4 - 6. Future work . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 - 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 - 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 - 10. Normative References . . . . . . . . . . . . . . . . . . . . . 5 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 + 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 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 intermediate node is not aware of them, the intermediate node cannot proceed further in the header chain since it does not know where the unknown header ends and the next header begins. The main issue is that the extension header format is not standardized and hence it is not possible to skip past the unknown header. This document intends to define a standard format for IPv6 extension headers. + Also, Several existing deployed IPv6 routers and several existing + deployed IPv6 firewalls are capable of parsing past or ignoring all + currently defined IPv6 Extension Headers (e.g. to examine transport- + layer header fields) at wire-speed (e.g. by using custom ASICs for + packet processing). Hence, one must also consider that any new IPv6 + Extension Header will break IPv6 deployments that use these existing + capabilities. + + Any IPv6 header or option that has hop-by-hop behaviour and is + intended for general use in the public IPv6 Internet could be + subverted to create an attack on IPv6 routers processing packets + containing such a header or option. Reports from the field indicate + that some IP routers deployed within the global Internet are + configured either to ignore the presence of headers with hop-by-hop + behaviour or to drop packets containing headers with hop-by-hop + behaviour. + 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. Applicability The base IPv6 standard [RFC2460] allows the use of both extension headers and destination options in order to encode optional @@ -98,24 +115,54 @@ options to encode this information, provides more flexible handling characteristics and better backward compatibility than using extension headers. Because of this, implementations SHOULD use destination options as the preferred mechanism for encoding optional destination information, and use a new extension header only if destination options do not satisfy their needs. The request for creation of a new IPv6 extension header MUST be accompanied by an specific explanation of why destination options could not be used to convey this information. + The base IPv6 standard [RFC2460] defines 3 extension headers (i.e. + Routing Header, Destination Options Header, Hop-by-Hop Options + Header) to be used for any new IPv6 options. The same standard only + allows the creation of new Extension Headers in limited circumstances + [RFC2460] Section 4.6. + + As noted above, the use of any option with Hop-by-Hop behaviour can + be problematic in the global public Internet. So new IPv6 Extension + Header(s) having hop-by-hop behaviour MUST NOT be created or + specified. Also, new options for the existing Hop-by-Hop Header + SHOULD NOT be created or specified unless no alternative is feasible. + Any proposal to create a new option for the existing Hop-by-Hop + Header MUST include a detailed explanation of why the hop-by-hop + behaviour is absolutely essential in the Internet-Draft proposing the + new option with hop-by-hop behaviour. + + The use of IPv6 Destination Options to encode information provides + more flexible handling characteristics and better backward + compatibility than using a new Extension Header. Because of this, + new optional information to be sent SHOULD be encoded in a new option + for the existing IPv6 Destination Options Header. + + 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 TLV format so that it is possible for nodes to skip over + a consistent format so that it is possible for nodes to skip over unknown extension headers and continue to further process the 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 | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | | . .