Internet DRAFT - draft-cao-mif-ifs
draft-cao-mif-ifs
MIF Working Group Z. Cao
Internet-Draft D. Liu
Intended status: Informational China Mobile
Expires: August 5, 2010 February 2010
IP Family Selection for MIF Host
draft-cao-mif-ifs-01
Abstract
This document attempts to summarize the problems that are not
addressed by current default address selection algorithms.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Summary . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Problem 1: NAT64 or NAT44? . . . . . . . . . . . . . . . . 4
2.2. Problem #2: NAT464 or NAT46? . . . . . . . . . . . . . . . 4
2.3. Problem #3: Self-assigned or Shared Addresses . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
5. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
Default Address Selection algorithms defined in RFC3484 [RFC3484]
specify default behavior for all IPv6 implementations. By default,
IPv6 is preferred over IPv4 for dual stack host. Some specific
scenarios in IP family selection have not been considered in RFC3484.
This document attempts to summarize the problems regarding IP family
selection.
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2. Problem Summary
2.1. Problem 1: NAT64 or NAT44?
If a dual stack host is configured with a DNS64 server [DNS64] and
communicates with an IPv4 only server, the synthesized AAAA record
will be preferred over the A record. So the dual stack host will
choose IPv6 to communicate with IPv4 and packets will go through the
NAT64 translator instead of NAT44.
Draft [DNS64-Config] identifies this problem and introduces serveral
solutions to this problem.
2.2. Problem #2: NAT464 or NAT46?
On a BIS/BIA enabled host, if the server is IPv4 only, the Extension
Name Resolver will return a type A record to the application and
normally IP traffic will go through the NAT64 gateway as in
PNAT[I-D.huang-behave-pnat].
If the server is upgraded to dual stack, the ENR on the host will get
both an A and an AAAA record. According to RFC3484 [RFC3484], the
host will prefer communicating using the IPv6 address and translation
will be conducted in NAT46. But problems arises for those
applications that need ALG. There may need ALG for those
applications on the host. If no ALG functions are available on the
host, the communication will fail. So in this case, the BIA/BIS
enabled host is desired to retain communicating. via NAT464.
2.3. Problem #3: Self-assigned or Shared Addresses
RFC3484 should consider the effect of non-meaningful IPv4 address (in
PNAT [I-D.huang-behave-pnat]) and IANA assigned shared IPv4 address
in DS-Lite [I.D-GI-DSL], and define cope for these addresses.
For example, the dual stack host has been assigned an IPv4 address
(public or private), and has been assigned an IPv6 prefix and self-
assigned IPv4 address, When the DNS returns an A record, the dual
stack host should have a specific way to choose which IPv4 address is
preferred. Suppose only an AAAA record is returned, on a BIA/BIS
enabled host with only IPv4 application, the DNS resolver will return
the mapped IPv4 address to the application. The source address
selection algorithm is left to select an appropriate source address
for communication. In this case, if the network assigned IPv4
address is selected, communication may fail.
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3. Security Considerations
TBD.
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4. IANA Considerations
This document does not require any IANA actions.
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5. Normative References
[DNS64] Bagnulo, M., "DNS64: DNS extensions for Network Address
Translation from IPv6 Clients to IPv4 Servers",
December 2009, <draft-ietf-behave-dns64-05.txt (work in
progress)>.
[DNS64-Config]
Wing, D., "DNS64 Resolvers and Dual-Stack Hosts",
Oct 2009, <draft-wing-behave-dns64-config-01.txt (work in
progress)>.
[I-D.huang-behave-pnat]
Huang, B. and H. Deng, "Prefix NAT: Host based IPv6
translation", December 2009,
<draft-huang-behave-pnat-01.txt (work in progress)>.
[I-D.huang-bia-bis]
Huang, B., Deng, H., and T. Savolainen, "Dual Stack Hosts
Using "Bump-in-the-API" (BIA)", October 2009,
<draft-huang-behave-rfc3338bis-00.txt (work in progress)>.
[I-D.huang-bis-bis]
Huang, B., Deng, H., and T. Savolainen, "Dual Stack Hosts
using the "Bump-In-the-Stack" Technique (BIS)",
October 2009, <draft-huang-behave-rfc2767bis-00.txt (work
in progress)>.
[I.D-GI-DSL]
Brockners, F. and S. Gundavelli, "Gateway Initiated Dual-
Stack Lite Deployment", December 2009, <draft-gundavelli-
softwire-gateway-init-ds-lite-01.txt(work in progress)>.
[NAT64] Bagnulo, M., "NAT64: Network Address and Protocol
Translation from IPv6 Clients to IPv4 Servers",
draft-bagnulo-behave-nat64-03.txt (work in progress),
March 2009.
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
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Authors' Addresses
Zhen Cao
China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District
Beijing 100053
China
Email: zehn.cao@gmail.com
Dapeng Liu
China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District
Beijing 100053
China
Email: liudapeng@chinamobile.com
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