draft-ietf-v6ops-ivi-icmp-address-06.txt   draft-ietf-v6ops-ivi-icmp-address-07.txt 
Network Working Group X. Li Network Working Group X. Li
Internet-Draft C. Bao Internet-Draft C. Bao
Intended status: BCP CERNET Center/Tsinghua Updates: 6145 (if approved) CERNET Center/Tsinghua
Expires: March 15, 2013 University Intended status: Standards Track University
D. Wing Expires: April 15, 2013 D. Wing
R. Vaithianathan R. Vaithianathan
Cisco Cisco
G. Huston G. Huston
APNIC APNIC
September 11, 2012 October 12, 2012
Stateless Source Address Mapping for ICMPv6 Packets Stateless Source Address Mapping for ICMPv6 Packets
draft-ietf-v6ops-ivi-icmp-address-06 draft-ietf-v6ops-ivi-icmp-address-07
Abstract Abstract
A stateless IPv4/IPv6 translator may receive ICMPv6 packets A stateless IPv4/IPv6 translator may receive ICMPv6 packets
containing non IPv4-translatable addresses as the source. These containing non IPv4-translatable addresses as the source. These
packets should be passed across the translator as ICMP packets packets should be passed across the translator as ICMP packets
directed to the IPv4 destination. This document presents directed to the IPv4 destination. This document presents
recommendations for source address translation in ICMPv6 headers to recommendations for source address translation in ICMPv6 headers to
handle such cases. handle such cases.
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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 March 15, 2013. This Internet-Draft will expire on April 15, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 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
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. Problem Statement and Considerations . . . . . . . . . . . . . 3 3. Problem Statement and Considerations . . . . . . . . . . . . . 3
3.1. Considerations . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Considerations . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Recommendations . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Recommendations . . . . . . . . . . . . . . . . . . . . . . 4
4. ICMP Extension . . . . . . . . . . . . . . . . . . . . . . . . 4 4. ICMP Extension . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Stateless Address Mapping Algorithm . . . . . . . . . . . . . . 4 5. Stateless Address Mapping Algorithm . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . . 5 9.1. Normative References . . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . . 6 9.2. Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
[RFC6145] section 5.2 of the "IP/ICMP Translation Algorithm" [RFC6145] section 5.2 of the "IP/ICMP Translation Algorithm"
document. states that "the IPv6 addresses in the ICMPv6 header may document. states that "the IPv6 addresses in the ICMPv6 header may
not be IPv4-translatable addresses and there will be no corresponding not be IPv4-translatable addresses and there will be no corresponding
IPv4 addresses representing this IPv6 address. In this case, the IPv4 addresses representing this IPv6 address. In this case, the
translator can do stateful translation. A mechanism by which the translator can do stateful translation. A mechanism by which the
translator can instead do stateless translation is left for future translator can instead do stateless translation is left for future
work." This document, Stateless Source Address Mapping for ICMPv6 work." This document, Stateless Source Address Mapping for ICMPv6
Packets, provides recommendations for this case. Packets, provides recommendations for this case.
For the purposes of this document, the term IPv4-translatable
address" is as defined in Section 2.2 of [RFC6052].
2. Notational Conventions 2. Notational Conventions
The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in [RFC2119]. document, are to be interpreted as described in [RFC2119].
3. Problem Statement and Considerations 3. Problem Statement and Considerations
When a stateless IPv4/IPv6 translator receives an ICMPv6 message When a stateless IPv4/IPv6 translator receives an ICMPv6 message
[RFC4443] (for example "Packet Too Big") sourced from an non-IPv4- [RFC4443] (for example "Packet Too Big") sourced from an non-IPv4-
translatable IPv6 address, bound for to an IPv4-translatable IPv6 translatable IPv6 address, bound for to an IPv4-translatable IPv6
address, the translator needs to pick a source address with which to address, the translator needs to pick a source address with which to
generate an ICMP message. For the reasons discussed below, this generate an ICMP message. For the reasons discussed below, this
choice is problematic. choice is problematic.
3.1. Considerations 3.1. Considerations
The source address used, should not cause the ICMP packet to be a The source address used, SHOULD NOT cause the ICMP packet to be
candidate for discarding. The possibility of uRPF filters in the discarded. It SHOULD NOT be drawn from [RFC1918] address space,
path are a critical consideration [RFC3704] which precludes the use because [RFC1918] sourced packets are likely to be subject to uRPF
of private IPv4 address space [RFC1918] in this context. [RFC3704] filtering.
IPv4/IPv6 translation is intended for use in contexts where IPv4 IPv4/IPv6 translation is intended for use in contexts where IPv4
addresses may not be readily available, so it is not considered addresses may not be readily available, so it is not considered
appropriate to assign IPv4-translatable IPv6 addresses for all appropriate to assign IPv4-translatable IPv6 addresses for all
internal points in the IPv6 network that may originate ICMPv6 internal points in the IPv6 network that may originate ICMPv6
messages. messages.
Another consideration for source selection is that it be possible for Another consideration for source selection is that it should be
the IPv4 recipients of the ICMP message to be able to distinguish possible for the IPv4 recipients of the ICMP message to be able to
between different IPv6 network origination of ICMPv6 messages, (for distinguish between different IPv6 network origination of ICMPv6
example, to support a traceroute diagnostic utility that provides messages, (for example, to support a traceroute diagnostic utility
some limited network level visibility across the IPv4/IPv6 that provides some limited network level visibility across the IPv4/
translator). This consideration implies that an IPv4/IPv6 translator IPv6 translator). This consideration implies that an IPv4/IPv6
needs to have a pool of IPv4 addresses for mapping the source address translator needs to have a pool of IPv4 addresses for mapping the
of ICMPv6 packets generated from different origins, or to include the source address of ICMPv6 packets generated from different origins, or
IPv6 source address information for mapping the source address by to include the IPv6 source address information for mapping the source
others means. Currently, the TRACEROUTE and MTR [MTR] are the only address by others means. Currently, the TRACEROUTE and MTR [MTR] are
consumers of translated ICMPv6 messages that care about the ICMPv6 the only consumers of translated ICMPv6 messages that care about the
source address. ICMPv6 source address.
3.2. Recommendations 3.2. Recommendations
The recommended approach to source selection is to use the a single The recommended approach to source selection is to use the a single
(or small pool) of public IPv4 address as the source address of the (or small pool) of public IPv4 address as the source address of the
translated ICMP message and leverage ICMP extension [RFC5837] to translated ICMP message and leverage ICMP extension [RFC5837] to
include IPv6 address as an Interface IP Address Sub-Object. include IPv6 address as an Interface IP Address Sub-Object.
4. ICMP Extension 4. ICMP Extension
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address belongs to the translator, not the originating node can also address belongs to the translator, not the originating node can also
be considered. be considered.
5. Stateless Address Mapping Algorithm 5. Stateless Address Mapping Algorithm
If a pool of public IPv4 addresses is configured on the translator, If a pool of public IPv4 addresses is configured on the translator,
it is RECOMMENDED to randomly select the IPv4 source address from the it is RECOMMENDED to randomly select the IPv4 source address from the
pool. Random selection reduces the probability that two ICMP pool. Random selection reduces the probability that two ICMP
messages elicited by the same TRACEROUTE might specify the same messages elicited by the same TRACEROUTE might specify the same
source address and, therefore, erroneously present the appearance of source address and, therefore, erroneously present the appearance of
a routing loop. An enhanced traceroute application is RECOMMENDED in a routing loop.
order to obtain the IPv6 source addresses which generated the ICMPv6
messages. [RFC5837] extensions and an enhanced traceroute application, if used,
will reveal the IPv6 source addresses which generated the original
ICMPv6 messages.
6. Security Considerations 6. Security Considerations
This document recommends the generation of IPv4 ICMP messages from This document recommends the generation of IPv4 ICMP messages from
IPv6 ICMP messages. These messages would otherwise have been IPv6 ICMP messages. These messages would otherwise have been
discarded. It is not expected that new considerations result from discarded. It is not expected that new considerations result from
this change. As with a number of ICMP messages, a spoofed source this change. As with a number of ICMP messages, a spoofed source
address may result in replies arriving at hosts that did not expect address may result in replies arriving at hosts that did not expect
them using the facility of the translator. them using the facility of the translator.
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Networks", BCP 84, RFC 3704, March 2004. Networks", BCP 84, RFC 3704, March 2004.
[RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control [RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control
Message Protocol (ICMPv6) for the Internet Protocol Message Protocol (ICMPv6) for the Internet Protocol
Version 6 (IPv6) Specification", RFC 4443, March 2006. Version 6 (IPv6) Specification", RFC 4443, March 2006.
[RFC5837] Atlas, A., Bonica, R., Pignataro, C., Shen, N., and JR. [RFC5837] Atlas, A., Bonica, R., Pignataro, C., Shen, N., and JR.
Rivers, "Extending ICMP for Interface and Next-Hop Rivers, "Extending ICMP for Interface and Next-Hop
Identification", RFC 5837, April 2010. Identification", RFC 5837, April 2010.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
October 2010.
[RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation [RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", RFC 6145, April 2011. Algorithm", RFC 6145, April 2011.
9.2. Informative References 9.2. Informative References
[MTR] "http://www.bitwizard.nl/mtr/". [MTR] "http://www.bitwizard.nl/mtr/".
Authors' Addresses Authors' Addresses
Xing Li Xing Li
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