draft-ietf-v6ops-addr-select-ps-08.txt   draft-ietf-v6ops-addr-select-ps-09.txt 
IPv6 Operations Working Group A. Matsumoto IPv6 Operations Working Group A. Matsumoto
Internet-Draft T. Fujisaki Internet-Draft T. Fujisaki
Intended status: Informational NTT Intended status: Informational NTT
Expires: December 14, 2008 R. Hiromi Expires: December 19, 2008 R. Hiromi
Intec Netcore Intec Netcore
K. Kanayama K. Kanayama
INTEC Systems INTEC Systems
June 12, 2008 June 17, 2008
Problem Statement of Default Address Selection in Multi-prefix Problem Statement of Default Address Selection in Multi-prefix
Environment: Operational Issues of RFC3484 Default Rules Environment: Operational Issues of RFC3484 Default Rules
draft-ietf-v6ops-addr-select-ps-08.txt draft-ietf-v6ops-addr-select-ps-09.txt
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This Internet-Draft will expire on December 14, 2008. This Internet-Draft will expire on December 19, 2008.
Copyright Notice
Copyright (C) The IETF Trust (2008).
Abstract Abstract
A single physical link can have multiple prefixes assigned to it. In A single physical link can have multiple prefixes assigned to it. In
that environment, end hosts might have multiple IP addresses and be that environment, end hosts might have multiple IP addresses and be
required to use them selectively. RFC 3484 defines default source required to use them selectively. RFC 3484 defines default source
and destination address selection rules and is implemented in a and destination address selection rules and is implemented in a
variety of OS's. But, it has been too difficult to use operationally variety of OS's. But, it has been too difficult to use operationally
for several reasons. In some environment where multiple prefixes are for several reasons. In some environment where multiple prefixes are
assigned on a single physical link, the host using the default assigned on a single physical link, the host using the default
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2.2.1. IPv4 or IPv6 prioritization . . . . . . . . . . . . . 10 2.2.1. IPv4 or IPv6 prioritization . . . . . . . . . . . . . 10
2.2.2. ULA and IPv4 dual-stack environment . . . . . . . . . 11 2.2.2. ULA and IPv4 dual-stack environment . . . . . . . . . 11
2.2.3. ULA or Global Prioritization . . . . . . . . . . . . . 12 2.2.3. ULA or Global Prioritization . . . . . . . . . . . . . 12
3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4. Security Considerations . . . . . . . . . . . . . . . . . . . 14 4. Security Considerations . . . . . . . . . . . . . . . . . . . 14
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1. Normative References . . . . . . . . . . . . . . . . . . . 14 6.1. Normative References . . . . . . . . . . . . . . . . . . . 14
6.2. Informative References . . . . . . . . . . . . . . . . . . 15 6.2. Informative References . . . . . . . . . . . . . . . . . . 15
Appendix A. Appendix. Revision History . . . . . . . . . . . . . 15 Appendix A. Appendix. Revision History . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
Intellectual Property and Copyright Statements . . . . . . . . . . 17 Intellectual Property and Copyright Statements . . . . . . . . . . 17
1. Introduction 1. Introduction
In IPv6, a single physical link can have multiple prefixes assigned In IPv6, a single physical link can have multiple prefixes assigned
to it. In such cases, an end-host may have multiple IP addresses to it. In such cases, an end-host may have multiple IP addresses
assigned to an interface on that link. In the IPv4-IPv6 dual stack assigned to an interface on that link. In the IPv4-IPv6 dual stack
environment or in a site connected to both a ULA [RFC4193] and environment or in a site connected to both a ULA [RFC4193] and
Globally routable networks, an end-host typically has multiple IP Globally routable networks, an end-host typically has multiple IP
addresses. These are examples of the networks that we focus on in addresses. These are examples of the networks that we focus on in
this document. In such an environment, an end-host may encounter this document. In such an environment, an end-host may encounter
some communication troubles. some communication troubles.
Inappropriate source address selection at the end-host causes Inappropriate source address selection at the end-host causes
unexpected asymmetric routing, filtering by a router or discarding of unexpected asymmetric routing, filtering by a router or discarding of
packets bacause there is no route to the host. packets because there is no route to the host.
Considering a multi-prefix environment, destination address selection Considering a multi-prefix environment, destination address selection
is also important for correct or better communication establishment. is also important for correct or better communication establishment.
RFC 3484 [RFC3484] defines default source and destination address RFC 3484 [RFC3484] defines default source and destination address
selection algorithms and is implemented in a variety of OS's. But, selection algorithms and is implemented in a variety of OS's. But,
it has been too difficult to use operationally for several reasons, it has been too difficult to use operationally for several reasons,
such as lack of autoconfiguration method. There are some problematic such as lack of autoconfiguration method. There are some problematic
cases where the hosts using the default address selection rules cases where the hosts using the default address selection rules
encounter communication troubles. encounter communication troubles.
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This document describes such possibilities of incorrect address This document describes such possibilities of incorrect address
selection which leads to dropping packets and communication failure. selection which leads to dropping packets and communication failure.
1.1. Scope of this document 1.1. Scope of this document
As other mechanisms already exist, the multi-homing techniques for As other mechanisms already exist, the multi-homing techniques for
achieving redundancy are basically out of our scope. achieving redundancy are basically out of our scope.
We focus on an end-site network environment and unmanaged hosts in We focus on an end-site network environment and unmanaged hosts in
such an environment. This is because address selection behavior at such an environment. This is because address selection behavior at
this kind of hosts is difficult to manipulate owing to the users's this kind of hosts is difficult to manipulate owing to the users'
lack of knowledge, hosts' location, or massiveness of the hosts. lack of knowledge, hosts' location, or massiveness of the hosts.
The scope of this document is to sort out problematic cases related The scope of this document is to sort out problematic cases related
to address selection. It includes problems that can be solved in the to address selection. It includes problems that can be solved in the
framework of RFC 3484 and problems that cannot. For the latter, RFC framework of RFC 3484 and problems that cannot. For the latter, RFC
3484 might be modified to meet their needs, or another address 3484 might be modified to meet their needs, or another address
selection solution might be necessary. For the former, an additional selection solution might be necessary. For the former, an additional
mechanism that mitigates the operational difficulty might be mechanism that mitigates the operational difficulty might be
necessary. necessary.
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matching algorithm chooses 2001:db8:8000:1::100 for the source matching algorithm chooses 2001:db8:8000:1::100 for the source
address. In this case, the packet goes through ISP1 and may be address. In this case, the packet goes through ISP1 and may be
filtered by ISP1's ingress filter. Even if the packet is not filtered by ISP1's ingress filter. Even if the packet is not
filtered by ISP1, a return packet from Host-C cannot possibly be filtered by ISP1, a return packet from Host-C cannot possibly be
delivered to Host-A because the return packet is destined for 2001: delivered to Host-A because the return packet is destined for 2001:
db8:8000:1::100, which is closed from the Internet. db8:8000:1::100, which is closed from the Internet.
The important point is that each host chooses a correct source The important point is that each host chooses a correct source
address for a given destination address. To solve this kind of address for a given destination address. To solve this kind of
network policy based address selection problems, it is likely that network policy based address selection problems, it is likely that
delivering addtional information to a node fits better than delivering additional information to a node fits better than
algorithmic solutions that are local to the node. algorithmic solutions that are local to the node.
Solution analysis: Solution analysis:
This problem can be solved in the RFC 3484 framework. For This problem can be solved in the RFC 3484 framework. For
example, configuring some address selection policies into Host-A's example, configuring some address selection policies into Host-A's
RFC 3484 policy table can solve this problem. RFC 3484 policy table can solve this problem.
2.1.4. Combined Use of Global and ULA 2.1.4. Combined Use of Global and ULA
============ ============
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[Fig. 5] [Fig. 5]
Solution analysis: Solution analysis:
This problem can be mitigated in the RFC 3484 framework. For This problem can be mitigated in the RFC 3484 framework. For
example, configuring some address selection policies into Host's example, configuring some address selection policies into Host's
RFC 3484 policy table can solve this problem. RFC 3484 policy table can solve this problem.
2.1.6. Multicast Source Address Selection 2.1.6. Multicast Source Address Selection
This case is an example of site-local or global prioritization. When This case is an example of site-local or global unicast
you send a multicast packet across site-borders, the source address prioritization. When you send a multicast packet across site-
of the multicast packet should be a globally routable address. The borders, the source address of the multicast packet should be a
longest matching algorithm, however, selects a ULA if the sending globally routable address. The longest matching algorithm, however,
host has both a ULA and a Global Unicast Address. selects a ULA if the sending host has both a ULA and a Global Unicast
Address.
Solution analysis: Solution analysis:
This problem can be solved in the RFC 3484 framework. For This problem can be solved in the RFC 3484 framework. For
example, configuring some address selection policies into the example, configuring some address selection policies into the
sending host's RFC 3484 policy table can solve this problem. sending host's RFC 3484 policy table can solve this problem.
2.1.7. Temporary Address Selection 2.1.7. Temporary Address Selection
RFC 3041 [RFC3041] defines a Temporary Address. The usage of a RFC 3041 [RFC3041] defines a Temporary Address. The usage of a
Temporary Address has both pros and cons. That is good for viewing Temporary Address has both pros and cons. That is good for viewing
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IPv6 [RFC3775] network. IPv6 [RFC3775] network.
The Future Work section in RFC 3041 discusses that an API extension The Future Work section in RFC 3041 discusses that an API extension
might be necessary to achieve a better address selection mechanism might be necessary to achieve a better address selection mechanism
with finer granularity. with finer granularity.
Solution analysis: Solution analysis:
This problem can not be solved in the RFC 3484 framework. A This problem can not be solved in the RFC 3484 framework. A
possible solution is to make applications to select desirable possible solution is to make applications to select desirable
addresses by using the IPv6 Socket API for Source Address addresses by using the IPv6 Socket API for Source Address
Selection defind in RFC 5014 [RFC5014]. Selection defined in RFC 5014 [RFC5014].
2.2. Destination Address Selection 2.2. Destination Address Selection
2.2.1. IPv4 or IPv6 prioritization 2.2.1. IPv4 or IPv6 prioritization
The default policy table gives IPv6 addresses higher precedence than The default policy table gives IPv6 addresses higher precedence than
IPv4 addresses. There seem to be many cases, however, where network IPv4 addresses. There seem to be many cases, however, where network
administrators want to control the address selection policy of end- administrators want to control the address selection policy of end-
hosts the other way around. hosts the other way around.
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[RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6 [RFC5014] Nordmark, E., Chakrabarti, S., and J. Laganier, "IPv6
Socket API for Source Address Selection", RFC 5014, Socket API for Source Address Selection", RFC 5014,
September 2007. September 2007.
6.2. Informative References 6.2. Informative References
Appendix A. Appendix. Revision History Appendix A. Appendix. Revision History
01: 01:
IP addresse notations changed to documentation address. IP address notations changed to documentation address.
Description of solutions deleted. Description of solutions deleted.
02: 02:
Security considerations section rewritten according to comments Security considerations section rewritten according to comments
from SECDIR. from SECDIR.
03: 03:
Intended status changed to Informational. Intended status changed to Informational.
04: 04:
This version reflects comments from IESG members. This version reflects comments from IESG members.
05: 05:
This version reflects comments from IESG members and Bob Hinden. This version reflects comments from IESG members and Bob Hinden.
06: 06:
This version reflects comments from Thomas Narten. This version reflects comments from Thomas Narten.
07: 07:
This version reflects comments from Alfred Hoenes. This version reflects comments from Alfred Hoenes.
08: 08:
Solution analysis for the section 2.1.6 was added. Solution analysis for the section 2.1.6 was added.
09:
Typos were fixed, thanks to Jari Arrko.
Authors' Addresses Authors' Addresses
Arifumi Matsumoto Arifumi Matsumoto
NTT PF Lab NTT PF Lab
Midori-Cho 3-9-11 Midori-Cho 3-9-11
Musashino-shi, Tokyo 180-8585 Musashino-shi, Tokyo 180-8585
Japan Japan
Phone: +81 422 59 3334 Phone: +81 422 59 3334
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attempt made to obtain a general license or permission for the use of attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
ietf-ipr@ietf.org. ietf-ipr@ietf.org.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
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