Internet Engineering Task Force S. Miyakawa
Internet-Draft Y. Shirasaki
Expires: January 1, 2009 NTT Communications
June 30, 2008
1 + /64s as IPv6 Standard Access Model
draft-miyakawa-1plus64s-00
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Abstract
This document proposes the "standard" address assignment scheme for
IPv6 access network which uses RA or DHCPv6 to assign an global IPv6
address to the WAN interface of the CPE and DHCPv6 PD on the upstream
link of CPE to delegate one or more /64 prefixes to the CPE.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. General Considerations . . . . . . . . . . . . . . . . . . . . 3
3. 1+/64s scheme . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5
Intellectual Property and Copyright Statements . . . . . . . . . . 6
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1. Introduction
This document describes about the "standard" address assignment
scheme for IPv6 access network for especially residential or SOHO
service.
2. General Considerations
In IPv4 environment, there is a de-fact standard method to subscribe
ISP service. Usually, PPP (Point to Point Protocol) is used as an
abstraction of the user subscription in IPv4 only environment. A PPP
connection connects an access concentrator and a customer premises
equipment (CPE). One single global IPv4 address is assigned to the
WAN interface of the CPE. If CPE is a router, typically, CPE does
"network address translation (NAT)" and gives [RFC1918] based private
addresses to the hosts behind the CPE such as an personal computer
(PC) and so on. Even if the CPE is a bridging device, a PC beyond
CPE terminates PPP (PPPoE maybe) by itself and receives a global IPv4
address to be used. In each cases, from an access concentrator point
of view, there is no difference. The model is quite simple. It
gives to the "customer" one global IPv4 address. That's all.
On the other hand, if we think about IPv6 ISP, this model does not
work well, because there is no NAT in IPv6. Simply, we cannot use
"One global IPv6 address" model to assign global IPv6 addresses to
all machines behind the CPE router. We have to rely on some
different model.
3. 1+/64s scheme
+-----+ +-- PC
+---------------------+ | | |
Internet <---+ access concentrator +--- uplink ---+ CPE +---+
+---------------------+ (WAN) | | |
+-----+ LAN
Figure 1: Network Model
"1+/64s" is quite simple scheme.
(A) Use RA or DHCPv6 to assign an global IPv6 address to the WAN
interface of the CPE. Do not leave the link between the access
concentrator and the CPE (the upstream link) link-local address
only.
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(B) Use DHCPv6 PD the upstream link to delegate one or more /64
prefixes to the CPE so that it can use those prefixes to
configure LANs behind it.
4. Discussion
The reason why the condition (A) is needed is that there are "strong
model" implementations of the Internet Protocol. When we wrote
[RFC4241] ("A Model of IPv6/IPv4 Dual Stack Internet Access Service"
an Informational RFC describing NTT Communications' native IPv4/v6
dual stack ADSL service specification), we believed that there is no
need to use any global IPv6 address for the uplink. But, at the year
2007, when Microsoft Vista was released to the market, we found that
that operating system employs the strong host model shown in
[RFC1122].
In this case, if the WAN interface of the CPE has only link-local
address, any application on the CPE cannot use the global ip address
even if this CPE has delegated prefix for LAN interface but chose the
link-local address as its source address towards any destination on
the Internet. So, we need to assign a global IPv6 address to the WAN
interface on the CPE.
5. IANA Considerations
There are no IANA considerations.
6. Security Considerations
TBD
7. Normative References
[RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996.
[RFC4241] Shirasaki, Y., Miyakawa, S., Yamasaki, T., and A.
Takenouchi, "A Model of IPv6/IPv4 Dual Stack Internet
Access Service", RFC 4241, December 2005.
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Authors' Addresses
Shin Miyakawa
NTT Communications Corporation
Tokyo Opera City Tower 21F, 3-20-2 Nishi-Shinjuku, Shinjuku-ku
Tokyo 163-1421
Japan
Phone: +81 3 6800 3262
Email: miyakawa@nttv6.jp
Yasuhiro Shirasaki
NTT Communications Corporation
NTT Hibiya Bldg. 7F, 1-1-6 Uchisaiwai-cho, Chiyoda-ku
Tokyo 100-8019
Japan
Phone: +81 3 6700 8530
Email: yasuhiro@nttv6.jp
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