IPv6 Operations Working Group A. Matsumoto
Internet-Draft T. Fujisaki
Intended status: Informational NTT
Expires: November 16, 2007 R. Hiromi
K. Kanayama
Intec Netcore
May 15, 2007
Requirements for address selection mechanisms
draft-ietf-v6ops-addr-select-req-02.txt
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Abstract
In a multi-prefix environment, nodes could have multiple addresses on
one network interface. RFC 3484 defines source and destination
address-selection algorithm, which is commonly deployed in current
popular OSs. However, nodes could encounter some difficulties in
network communication when they use default address selection rules
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defined in RFC 3484. Some mechanisms for solving address selection
problems are proposed including the RFC 3484 policy table
distribution and ICMP error-based mechanisms. This document
describes the requirements for these address selection mechanisms.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements of Address Selection . . . . . . . . . . . . . . . 3
2.1. Effectiveness . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Timing . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Dynamic Behavior Update . . . . . . . . . . . . . . . . . . 4
2.4. Node-Specific Behavior . . . . . . . . . . . . . . . . . . 4
2.5. Application-Specific Behavior . . . . . . . . . . . . . . . 4
2.6. Multiple Interface . . . . . . . . . . . . . . . . . . . . 4
2.7. Central Control . . . . . . . . . . . . . . . . . . . . . . 4
2.8. Next-hop Selection . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Normative References . . . . . . . . . . . . . . . . . . . 5
5.2. Informative References . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
Intellectual Property and Copyright Statements . . . . . . . . . . 7
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1. Introduction
One physical network can have multiple logical networks. In that
case, an end-host has multiple IP addresses. ( e.g. In the IPv4-IPv6
dual-stack environment, in a site that uses both ULA [RFC4193] and
global scope addresses or in a site connected to multiple upstream
IPv6 networks) For such a host, RFC 3484 [RFC3484] defines default
address-selection rules for the source and destination addresses.
Today, the RFC 3484 mechanism is widely implemented in major OSs.
However, we and others have found that in many sites the default
address-selection rules are not appropriate for the network
structure. PS [I-D.ietf-v6ops-addr-select-ps] lists problematic
cases that resulted from incorrect address selection.
Though RFC 3484 made the address-selection behavior of a host
configurable, typical users cannot make use of that because of the
complexity of the mechanism and lack of knowledge about their network
topologies. Therefore, an address-selection autoconfiguration
mechanism is necessary, especially for unmanaged hosts of typical
users.
This document contains requirements for address-selection mechanisms
that enable hosts to perform appropriate address selection
automatically.
2. Requirements of Address Selection
Address-selection mechanisms have to fulfill the following seven
requirements.
2.1. Effectiveness
The mechanism can modify RFC 3484 default address-selection behavior
at nodes. As documented in PS [I-D.ietf-v6ops-addr-select-ps], the
default rules defined in RFC 3484 do not work properly in some
environment. Therefore, the mechanism has to be able to modify
address-selection behavior of a host.
2.2. Timing
Nodes can obtain address selection information when necessary. If
nodes need to have address-selection information before performing
address selection, then the mechanism has to provide a way for nodes
to obtain necessary information beforehand. The mechanism should not
degrade userbility. The mechanism should not enforce long address-
selection processing time upon users.
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2.3. Dynamic Behavior Update
Address-selection behavior of nodes can be dynamically updated. When
the network structure changes and address-selection behavior has to
be changed accordingly, a network administrator can modify the
address-selection behavior of nodes.
2.4. Node-Specific Behavior
The mechanism can support node-specific address-selection behavior.
Even when multiple nodes are on the same subnet, the mechanism should
be able to provide a method for the network administrator to make
nodes behave differently. For example, each node may have a
different set of assigned prefixes. In such a case, the appropriate
address-selection behavior may be different.
2.5. Application-Specific Behavior
The mechanism can support application-specific address-selection
behavior or combined use with an application-specific address-
selection mechanism such as address-selection APIs.
2.6. Multiple Interface
The mechanism can support those nodes equipped with multiple
interfaces. The mechanism has to assume that nodes have multiple
interfaces and makes address selection of those nodes work
appropriately.
2.7. Central Control
The address selection behavior of nodes can be centrally controlled.
A site administrator or a service provider can determine or have
effect on address-selection behavior at their users' hosts.
2.8. Next-hop Selection
The mechanism can control next-hop-selection behavior at hosts or
cooperate with other routing mechanisms, such as routing protocols
and RFC 4191 [RFC4191]. If the address-selection mechanism is used
with a routing mechanism, the two mechanisms has to be able to work
synchronousely.
3. Security Considerations
Incorrect address-selection can lead to serious security problems,
such as session hijack. However, we should note that address-
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selection is ultimately decided by nodes and their users. There are
no means to enforce a specific address-selection behavior upon every
end-host from outside of the host. Therefore, a network
administrator has to take countermeasures for unexpected address
selection.
4. IANA Considerations
This document has no actions for IANA.
5. References
5.1. Normative References
[I-D.ietf-v6ops-addr-select-ps]
Matsumoto, A., "Problem Statement of Default Address
Selection in Multi-prefix Environment: Operational Issues
of RFC3484 Default Rules",
draft-ietf-v6ops-addr-select-ps-01 (work in progress),
April 2007.
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
5.2. Informative References
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", RFC 4191, November 2005.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
Authors' Addresses
Arifumi Matsumoto
NTT PF Lab
Midori-Cho 3-9-11
Musashino-shi, Tokyo 180-8585
Japan
Phone: +81 422 59 3334
Email: arifumi@nttv6.net
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Tomohiro Fujisaki
NTT PF Lab
Midori-Cho 3-9-11
Musashino-shi, Tokyo 180-8585
Japan
Phone: +81 422 59 7351
Email: fujisaki@syce.net
Ruri Hiromi
Intec Netcore, Inc.
Shinsuna 1-3-3
Koto-ku, Tokyo 136-0075
Japan
Phone: +81 3 5665 5069
Email: hiromi@inetcore.com
Ken-ichi Kanayama
Intec Netcore, Inc.
Shinsuna 1-3-3
Koto-ku, Tokyo 136-0075
Japan
Phone: +81 3 5665 5069
Email: kanayama@inetcore.com
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