draft-ietf-6man-exthdr-02.txt   draft-ietf-6man-exthdr-03.txt 
6man Working Group S. Krishnan 6man Working Group S. Krishnan
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track j h. woodyatt Intended status: Standards Track j h. woodyatt
Expires: September 15, 2011 Apple Expires: December 29, 2011 Apple
E. Kline E. Kline
Google Google
J. Hoagland J. Hoagland
Symantec Symantec
M. Bhatia M. Bhatia
Alcatel-Lucent Alcatel-Lucent
March 14, 2011 June 27, 2011
An uniform format for IPv6 extension headers An uniform format for IPv6 extension headers
draft-ietf-6man-exthdr-02 draft-ietf-6man-exthdr-03
Abstract Abstract
In IPv6, optional internet-layer information is encoded in separate In IPv6, optional internet-layer information is encoded in separate
headers that may be placed between the IPv6 header and the transport headers that may be placed between the IPv6 header and the transport
layer header. There are a small number of such extension headers layer header. There are a small number of such extension headers
currently defined. This document defines a format for defining new currently defined. This document defines a format for defining new
IPv6 extension headers. IPv6 extension headers.
Status of this Memo Status of this Memo
skipping to change at page 1, line 41 skipping to change at page 1, line 41
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." 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 Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 17 skipping to change at page 2, line 17
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . . 3
3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Proposed IPv6 Extension Header format . . . . . . . . . . . . . 4 4. Proposed IPv6 Extension Header format . . . . . . . . . . . . . 5
5. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 4 5. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 6
6. Future work . . . . . . . . . . . . . . . . . . . . . . . . . . 4 6. Future work . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
10. Normative References . . . . . . . . . . . . . . . . . . . . . 5 10. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
The base IPv6 standard [RFC2460] defines extension headers as an The base IPv6 standard [RFC2460] defines extension headers as an
expansion mechanism to carry optional internet layer information. expansion mechanism to carry optional internet layer information.
Extension headers, with the exception of the hop-by-hop options Extension headers, with the exception of the hop-by-hop options
header, are not usually processed on intermediate nodes. However, header, are not usually processed on intermediate nodes. However,
some intermediate nodes such as firewalls, may need to look at the 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 transport layer header fields in order to make a decision to allow or
deny the packet. If new extension headers are defined and the deny the packet. If new extension headers are defined and the
intermediate node is not aware of them, the intermediate node cannot intermediate node is not aware of them, the intermediate node cannot
proceed further in the header chain since it does not know where the 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 unknown header ends and the next header begins. The main issue is
that the extension header format is not standardized and hence it is that the extension header format is not standardized and hence it is
not possible to skip past the unknown header. This document intends not possible to skip past the unknown header. This document intends
to define a standard format for IPv6 extension headers. 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 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Applicability 3. Applicability
The base IPv6 standard [RFC2460] allows the use of both extension The base IPv6 standard [RFC2460] allows the use of both extension
headers and destination options in order to encode optional headers and destination options in order to encode optional
skipping to change at page 4, line 5 skipping to change at page 5, line 5
options to encode this information, provides more flexible handling options to encode this information, provides more flexible handling
characteristics and better backward compatibility than using characteristics and better backward compatibility than using
extension headers. Because of this, implementations SHOULD use extension headers. Because of this, implementations SHOULD use
destination options as the preferred mechanism for encoding optional destination options as the preferred mechanism for encoding optional
destination information, and use a new extension header only if destination information, and use a new extension header only if
destination options do not satisfy their needs. The request for destination options do not satisfy their needs. The request for
creation of a new IPv6 extension header MUST be accompanied by an creation of a new IPv6 extension header MUST be accompanied by an
specific explanation of why destination options could not be used to specific explanation of why destination options could not be used to
convey this information. 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 4. Proposed IPv6 Extension Header format
This document proposes that all IPv6 extension headers be encoded in 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 unknown extension headers and continue to further process the header
chain. chain.
0 1 2 3 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 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 | | | Next Header | Hdr Ext Len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
. . . .
 End of changes. 8 change blocks. 
13 lines changed or deleted 60 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/