behave Working Group Z. Cao
Internet-Draft H. Deng
Intended status: Informational China Mobile
Expires: August 16, 2010 February 12, 2010
Dual Stack Hosts with DNS64
draft-cao-behave-dsdns64-00
Abstract
If a dual stack host is configured with a DNS64 server, the packet
will be routed through the NAT64 translator instead of the plain IPv4
router or NAT44. This document suggest the DNS64 should handle type
A DNS request normally to avoid packets being detoured to NAT64.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Workaround . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
5. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
If a dual stack host is configured with a DNS64 server [DNS64], the
packet will be routed through the NAT64 translator instead of the
plain IPv4 router or NAT44. This document suggest the DNS64 should
handle type A DNS request properly to avoid packets being detoured to
NAT64.
Draft [DNS64-Config] introduces serveral solutions to this problem.
Specifically, the host destination address selection policy table is
modified in order to give the synthesis AAAA record from the DNS64 a
lower precedence than native IPv4 address. So the destination
address selection algorithm will prefer the IPv4 address and
communication will be IPv4 oriented.
The problem is that DNS64 is only specific for AAAA request, and does
not specify whether and how to handle A query. So in the above
solution, DNS64 will return presumably only AAAA record. Even if the
host policy table is modified, host won't be able to select the IPv4
address.
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2. Workaround
A simple workaround way to this problem is introduced in this
section. We suggest the DNS64 should handle A request normally. So
dual stack host will be able to receive both A and AAAA response from
DNS64, and then destination address selection policy will take effect
and host will select IPv4 address for communication.
+-----------+ A & AAAA Query +----------+
| Dualstack |-------------------------------> | DNS64 |
| Host |<------------------------------- | |
+-----------+ A & AAAA Response +----------+
Figure 1: Dual stack host will DNS64
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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)>.
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Authors' Addresses
Zhen Cao
China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District
Beijing 100053
China
Email: zehn.cao@gmail.com
Hui Deng
China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District
Beijing 100053
China
Email: denghui@chinamobile.com
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