Internet Engineering Task Force J. Yamaguchi
Internet-Draft IIJ
Intended status: Informational Y. Shirasaki
Expires: July 7, 2012 S. Miyakawa
NTT Communications
A. Nakagawa
Japan Internet Exchange (JPIX)
H. Ashida
IS Consulting G.K.
January 4, 2012
NAT444 addressing models
draft-shirasaki-nat444-isp-shared-addr-07
Abstract
This document describes addressing models of NAT444. There are some
addressing models of NAT444. The addressing models have some issues
of network behaviors, operations, and addressing. This document
helps network architects to use NAT444 after IPv4 address exhaustion.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Addressing Models . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Global Address . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Private Address . . . . . . . . . . . . . . . . . . . . . . 4
2.2.1. Policy Based Routing Issue . . . . . . . . . . . . . . 4
2.2.2. Address Block Duplication Issue . . . . . . . . . . . . 4
2.2.3. Class-E Address (240/4) . . . . . . . . . . . . . . . . 4
2.2.4. ISP Shared Address . . . . . . . . . . . . . . . . . . 5
3. Example Architectures . . . . . . . . . . . . . . . . . . . . . 5
3.1. Direct Routing inside CGN . . . . . . . . . . . . . . . . . 5
3.2. CGN Bypassing . . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Global Address Customers inside CGN . . . . . . . . . . . . 7
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
7. Normative References . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
NAT444 [I-D.shirasaki-nat444] is one of solutions after IPv4 address
exhaustion. ISP can select some addressing models of NAT444. The
addressing models have some issues of network behaviors, operations,
and addressing. This document describes these issues and solutions.
It boosts up to deploy the IPv6 Internet.
2. Addressing Models
The key of addressing model is the address block between Customer
Premises Equipment (CPE) and Carrier Grade NAT (CGN)
[I-D.ietf-behave-lsn-requirements]. It's mentioned in this section.
The best addressing model is "ISP Shared Address" which is defined in
[I-D.shirasaki-isp-shared-addr] and briefly described in this
section.
2.1. Global Address
ISP cannot assign IPv4 Global Address any more after the exhaustion.
2.2. Private Address
It has two major problems.
2.2.1. Policy Based Routing Issue
If both source and destination address of the packet are inside CGN,
it has to go through CGN. The reason is that some servers reject
receiving packets when the source address of receiving packet is
Private Address. Therefore packets have to go through the CGN for
rewriting the source address from Private Address to Global Address.
Additionally, if Private Address and Global Address co-exist inside
CGN, the ISP has to use Policy Based Routing (PBR).
2.2.2. Address Block Duplication Issue
The Private Address in ISP's network could conflict with its
customer's network address. Many CPEs between customer's network and
ISP's network cannot route the packet under this situation. To avoid
this, ISP has to negotiate with its all customers not to use the
reserved Private Address block.
2.2.3. Class-E Address (240/4)
It is known that some equipment such as routers and servers reject
packets from or to this address block. So, to use this address block
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in ISP's network, ISP has to request its customers to replace their
equipment. In addition to that, ISP might have to replace their
equipment when it doesn't handle Class-E address packets properly.
2.2.4. ISP Shared Address
ISP Shared Address is the newly defined IPv4 address block that is to
be allocated from IANA free pool. It doesn't have any problem.
Spending some blocks from the exhausting IANA free pool could be
regarded as a problem, but from long view, this problem is much
smaller than its great merit. ISP Shared Address is defined in
[I-D.shirasaki-isp-shared-addr].
3. Example Architectures
This section explains example architectures how to design NAT444 with
ISP Shared Address.
3.1. Direct Routing inside CGN
This architecture enables direct communication between customers
inside same CGN. It has the following advantages.
o The packets don't go through CGN. (No hairpining)
o The customers inside CGN can use bidirectional applications (e.g.
TV Conference, VPN).
o No need to use Policy Based Routing.
(The IPv4 Internet)
| Global Address
+----+----+
| CGN |
+----+----+
|
ISP Shared +-----------+----------+ ISP Shared
Address | .......... | Address
+----+----+ : : +----+----+
| CPE NAT | : : | CPE NAT |
+----+----+ : : +----+----+
Private | : : | Private
Address | v v | Address
+----+----+ +----+----+
|IPv4 Host| |IPv4 Host|
+---------+ +---------+
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3.2. CGN Bypassing
This architecture is bypassing the NAT function of CGN. It has the
following advantage.
o The customers inside an ISP can use bidirectional applications
(e.g. TV Conference, VPN).
o Any communication in single ISP doesn't consume CGN external port.
o ISP's servers outside CGN can access CPE. (e.g. ICMP echo, SNMP,
remote access)
o ISP's servers outside CGN can distinguish which customer's
connection it receives. (e.g. DNS, Mail)
(The IPv4 Internet)
|
| +--------+ Network Monitor
| | Server | (ICMP echo, SNMP)
| +----+---+ DNS, Mail, Web, etc
Global | | ^
Address +----------------------+ :
| ....................
| . : |
+----+----+ : : +----+----+ bypass NAT:
| CGN | : bypass : | CGN | Dst=ISP's Global Address
+----+----+ : NAT : +----+----+ or ISP Shared Address
ISP Shared | : : |
Address | : : | ISP Shared Address
+----+----+ : : +----+----+
| CPE NAT | : : | CPE NAT |
+----+----+ : : +----+----+
Private | : : | Private
Address | v v | Address
+----+----+ +----+----+
|IPv4 Host| |IPv4 Host|
+---------+ +---------+
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3.3. Global Address Customers inside CGN
This architecture enables co-existing Global Address and ISP Shared
Address inside CGN.
It enables direct communications from ISP Shared Address customer to
Global Address customer inside same CGN. It has the following
advantage.
o The ISP can put ISP Shared Address customer and Global Address
customer in the same concentrator.
o The customers inside CGN can use bidirectional applications (e.g.
TV Conference, VPN).
o No need to use Policy Based Routing.
(The IPv4 Internet)
|
| Global Address
+----+----+
| CGN | bypass NAT: Src/Dst=Global Address
+----+----+
| Global Address and ISP Shared Address co-existing
+----------------------+
| ......... |
+----+----+ : : +----+----+
| Firewall| : : | CPE NAT |
+----+----+ : : +----+----+
Global | : : | Private
Address | v : | Address
+-----+-----+ +----+----+
|IPv4 Server| |IPv4 Host|
+-----------+ +---------+
4. Acknowledgements
Thanks for the input and review by Shirou Niinobe, Takeshi Tomochika,
Tomohiro Fujisaki, Dai Nishino, JP address community members, AP
address community members and JPNIC members.
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5. IANA Considerations
IANA is to allocate a certain size of address block from IANA free
pool. The size of it is described in [I-D.shirasaki-isp-shared-addr]
6. Security Considerations
There are no security considerations.
7. Normative References
[I-D.shirasaki-isp-shared-addr]
Yamagata, I., Miyakawa, S., Nakagawa, A., Yamaguchi, J.,
and H. Ashida, "ISP Shared Address",
draft-shirasaki-isp-shared-addr-06 (work in progress),
July 2011.
[I-D.ietf-behave-lsn-requirements]
Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A.,
and H. Ashida, "Common requirements for Carrier Grade NATs
(CGNs)", draft-ietf-behave-lsn-requirements-05 (work in
progress), November 2011.
[I-D.shirasaki-nat444]
Yamagata, I., Shirasaki, Y., Nakagawa, A., Yamaguchi, J.,
and H. Ashida, "NAT444", draft-shirasaki-nat444-04 (work
in progress), July 2011.
Authors' Addresses
Jiro Yamaguchi
Internet Initiative Japan Inc.
Jinbocho Mitsui Bldg., 1-105 Kanda Jinbo-cho, Chiyoda-ku
Tokyo 101-0051
Japan
Phone: +81 3 5205 6500
Email: jiro-y@iij.ad.jp
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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
Shin Miyakawa
NTT Communications Corporation
Granpark Tower 17F, 3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
Phone: +81 3 6733 8671
Email: miyakawa@nttv6.jp
Akira Nakagawa
Japan Internet Exchange Co., Ltd. (JPIX)
Otemachi Building 21F, 1-8-1 Otemachi, Chiyoda-ku
Tokyo 100-0004
Japan
Phone: +81 90 9242 2717
Email: a-nakagawa@jpix.ad.jp
Hiroyuki Ashida
IS Consulting G.K.
12-17 Odenma-cho, Nihonbashi, Chuo-ku
Tokyo 103-0011
Japan
Email: assie@hir.jp
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