IPv6 Universal Extension Header
draft-gont-6man-ipv6-universal-extension-header-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
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|---|---|---|---|
| Authors | Fernando Gont , Will (Shucheng) LIU | ||
| Last updated | 2014-01-30 | ||
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draft-gont-6man-ipv6-universal-extension-header-00
IPv6 maintenance Working Group (6man) F. Gont
Internet-Draft SI6 Networks / UTN-FRH
Updates: 6564 (if approved) W. Liu
Intended status: Standards Track Huawei Technologies
Expires: August 4, 2014 January 31, 2014
IPv6 Universal Extension Header
draft-gont-6man-ipv6-universal-extension-header-00
Abstract
This document analyzes a problem in the Uniform Format for IPv6
Extension Headers specified in RFC 6564, which results in forwarding
nodes and middle-boxes not being able to process an IPv6 Header Chain
if it contains an unrecognized IPv6 Extension Header that follows the
aforementioned Uniform Format. Additionally, it specifies a new IPv6
Extension Header - the Universal Extension Header - that overcomes
the aforementioned problem, and enables the extensibility of IPv6
without impairing middleboxes that need to process the entire IPv6
Header Chain. Finally, this document formally updates RFC 6564
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
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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 August 4, 2014.
Copyright Notice
Copyright (c) 2014 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
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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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
4. Updating RFC 6564 . . . . . . . . . . . . . . . . . . . . . . 3
5. Operation of the Universal Extension Header . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
There has recently been a lot of work about IPv6 Extension Headers.
Firstly, there has been research about the extent to which IPv6
Extension Headers are dropped in the public Internet [GONT-IEPG], and
debate about the motivation behind such policy
[I-D.taylor-v6ops-fragdrop]. Secondly, there has been a fair share
of work to improve some technicalities of IPv6 Extension Headers
[I-D.ietf-6man-oversized-header-chain] [RFC7045], in the hopes that
they can be reliably used in the public Internet.
A key challenge for IPv6 Extension Headers to be "usable" in the
public Internet is that they should not impair any middle-box's
ability to inspect the upper layer header (e.g., TCP source and
destination ports, etc.). One of the steps in that direction has
been the specification of a Uniform Format for IPv6 Extension Headers
[RFC6564], which is meant to be employed by any IPv6 Extension
Headers that might be defined in the future, such that middle-boxes
can still process the entire IPv6 header chain if the new extension
headers employ the Uniform Format.
Section 3 discusses a flaw in the Uniform Format for Extension
Headers specified in [RFC6564]. Section 4 formally updates
[RFC6564], specifying the new Universal Extension Header (UEH).
Section 5 explains how new IPv6 would be developed with the UEH.
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2. Terminology
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 RFC 2119 [RFC2119].
3. Problem Statement
A key problem with the Uniform Format for IPv6 Extension Headers lies
on the fat that both IPv6 Extension Headers and Transport Protocols
share the same namespace ("Next Header" registry/namespace). Thus,
there is now way to distinguish between an unrecognized IPv6
Extension Header and an unrecognized transport protocol. For
example, if a node were to receive an IPv6 packet that employs an
unsupported "Next Header" value, there is no way to tell whether the
next header corresponds to an Extension Header employing the Uniform
Format for IPv6 Extension Headers, or a new upper-layer protocol
(such as a transport protocol).
Clearly, employing the Uniform Format for IPv6 Extension Headers
"enables" the future extension of IPv6 and the processing of entire
IPv6 header chains containing unrecognized extension headers, at the
expense of preventing the deployment of new transport protocols or
other upper layer protocols.
4. Updating RFC 6564
The entire Section 4 of [RFC6564] is hereby replaced as follows:
New IPv6 Extension Headers MUST NOT be specified. Any IPv6
extensions that would require a new IPv6 Extension Header MUST be
implemented with the Universal Extension Header specified in this
document. This minimizes breakage in intermediate nodes that examine
these extension headers.
This document specifies a new IPv6 Extension Header: Universal
Extension Header. This Extension Header is identified by the value
[TBD] of [IANA-IP-PROTO]. The syntax of the Universal Extension
Header is:
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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 | Subtype | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| |
. .
. Subtype Specific Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Next Header
8-bit selector. Identifies the type of header immediately
following the extension header. Uses the same values as the IPv4
Protocol field [IANA-IP-PROTO].
Hdr Ext Len
8-bit unsigned integer. Length of the extension header in 8-octet
units, not including the first 8 octets.
Subtype
8-bit unsigned integer. Specifies the subtype for this extension
header. It uses a new namespace managed by IANA [IANA-UEH].
Subtype Specific Data
Variable length. Fields specific to this extension header/
Subtype.
The Universal Extension Header specified in this document MAY appear
multiple times in the same IPv6 packet.
5. Operation of the Universal Extension Header
This section discusses de operation of the Universal Extension
Header.
The goal of the UEH is to provide for a common syntax for all future
IPv6 extensions. Any future extension headers will be encoded in a
UEH, and will be identified by a specific UEH Subtype assigned by
IANA at the time the corresponding specification is published. The
UEH thus provides for the "common syntax" required to process
"unrecognized extensions", and the Subtype field identifies the
specific extension being encoded in the UEH. Any "future extension
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headers" would actually be new Subtypes (assigned by IANA) of the
UEH.
As a result, in the event an unrecognized Next Header value is
encountered by a node, the node will be able to assume that such Next
Header value identifies an upper-layer protocol, rather than an
extension header.
6. IANA Considerations
IANA is requested to create a new registry to maintain the Universal
Extension Header Subtypes [IANA-UEH].
7. Security Considerations
Enabling middle-boxes such as firewalls to inspect the entire IPv6
header chain even in the presence of unrecognized extensions allows
for security mechanisms to be implemented, and for proper functioning
of of other middle-boxes such as load-balancers.
8. Acknowledgements
The authors would like to thank [TBD] for providing valuable input on
earlier versions of this document.
9. Contributors
C.M. Heard identified the problems related with the Uniform Format
for IPv6 Extension Headers specified in [RFC6564], and participated
in the brainstorming that led to this document.
10. References
10.1. Normative References
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and
M. Bhatia, "A Uniform Format for IPv6 Extension Headers",
RFC 6564, April 2012.
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing
of IPv6 Extension Headers", RFC 7045, December 2013.
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10.2. Informative References
[I-D.ietf-6man-oversized-header-chain]
Gont, F., Manral, V., and R. Bonica, "Implications of
Oversized IPv6 Header Chains", draft-ietf-6man-oversized-
header-chain-09 (work in progress), November 2013.
[I-D.taylor-v6ops-fragdrop]
Jaeggli, J., Colitti, L., Kumari, W., Vyncke, E., Kaeo,
M., and T. Taylor, "Why Operators Filter Fragments and
What It Implies", draft-taylor-v6ops-fragdrop-02 (work in
progress), December 2013.
[GONT-IEPG]
Gont, F., "Fragmentation and Extension Header Support in
the IPv6 Internet", IEPG 88, November 3, 2013. Vancouver,
BC, Canada, 2013, <http://www.iepg.org/2013-11-ietf88/
fgont-iepg-ietf88-ipv6-frag-and-eh.pdf>.
[IANA-IP-PROTO]
Internet Assigned Numbers Authority, "Assigned Internet
Protocol Numbers", April 2011, <http://www.iana.org/
assignments/protocol-numbers/protocol-numbers.xhtml>.
[IANA-UEH]
Internet Assigned Numbers Authority, "Universal Extension
Header Subtypes", 2014.
Authors' Addresses
Fernando Gont
SI6 Networks / UTN-FRH
Evaristo Carriego 2644
Haedo, Provincia de Buenos Aires 1706
Argentina
Phone: +54 11 4650 8472
Email: fgont@si6networks.com
URI: http://www.si6networks.com
Will (Shucheng) Liu
Huawei Technologies
Bantian, Longgang District
Shenzhen 518129
P.R. China
Email: liushucheng@huawei.com
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