Internet Engineering Task Force Y. Shirasaki, Ed. Internet-Draft S. Miyakawa Expires: April 30, 2009 NTT Communications A. Nakagawa KDDI CORPORATION J. Yamaguchi IIJ H. Ashida iTSCOM October 27, 2008 NAT444 with ISP Shared Address draft-shirasaki-nat444-isp-shared-addr-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 30, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract This document describes a network model with ISP Shared Address and Carrier Grade NAT (CGN) called NAT444. NAT444 is the only scheme not Shirasaki, et al. Expires April 30, 2009 [Page 1] Internet-Draft NAT444 with ISP Shared Address October 2008 to require replacing Customer Premises Equipment (CPE) even if IPv4 address exhausted. But it must be noted that NAT444 has serious restrictions i.e. it limits the number of sessions per CPE so that rich applications such as AJAX and RSS feed cannot work well. Therefore, IPv6 which is free from such a difficulty has to be introduced into the network at the same time. In other words, NAT444 is just a tool to make IPv6 transition easy to be swallowed. It is designed for the days IPv4 and IPv6 co-existence. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Definition of NAT444 Model . . . . . . . . . . . . . . . . . . 3 3. Pros and Cons of NAT444 Model . . . . . . . . . . . . . . . . 4 3.1. Pros of NAT444 Model . . . . . . . . . . . . . . . . . . . 4 3.2. Cons of NAT444 Model . . . . . . . . . . . . . . . . . . . 4 4. Address Block of ISP's Network . . . . . . . . . . . . . . . . 4 4.1. Global Address . . . . . . . . . . . . . . . . . . . . . . 4 4.2. Private Address . . . . . . . . . . . . . . . . . . . . . 4 4.2.1. Hairpining Issue . . . . . . . . . . . . . . . . . . . 4 4.2.2. Address Block Duplication Issue . . . . . . . . . . . 5 4.3. Class-E Address (240/4) . . . . . . . . . . . . . . . . . 5 4.4. ISP Shared Address . . . . . . . . . . . . . . . . . . . . 5 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . . 6 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 Appendix A. Example IPv6 Transition Scenario . . . . . . . . . . 6 Appendix B. Example Architectures . . . . . . . . . . . . . . . . 9 B.1. Direct Routing inside CGN . . . . . . . . . . . . . . . . 9 B.2. CGN Bypassing . . . . . . . . . . . . . . . . . . . . . . 10 B.3. Global Address Customers inside CGN . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . . . 13 Shirasaki, et al. Expires April 30, 2009 [Page 2] Internet-Draft NAT444 with ISP Shared Address October 2008 1. Introduction IPv4 address is said to be run out soon. Unless ISP takes any action, it will not be able to provide the service to new customers. This document explains a NAT444 model. This model is base on the environment where customers have been using Private Address [RFC1918] inside their CPE, and the servers that have only IPv4 address will continue to exist on the Internet after the IPv4 address exhaustion. In this situation, IPv6 only hosts cannot reach IPv4 only hosts. It triggers ISPs to take actions for keeping assigning IPv4 address to their customers using non-Global IPv4 Address. NAT444 is one of the solutions for this issue. 2. Definition of NAT444 Model NAT444 Model is a network model that uses two Network Address and Port Translators (NAPTs) with three types of IPv4 address blocks. The first NAPT is in CPE, and the second NAPT is in Carrier Grade NAT (CGN) [I-D.nishitani-cgn]. CGN is supposed to be installed in the ISP's network. The first IPv4 address block is Private Address inside CPE. The second one is a IPv4 Address block between CPEs and CGN. It could be Global Address, Private Address (10/8), Class-E (240/4) [I-D.wilson-class-e], or (newly defined) ISP Shared Address. The third one is IPv4 Global Addresses that is outside CGN and directly connected to the IPv4 Internet. ( The IPv4 Internet ) [ISP-A] [ISP-B] | | IPv4 Global Address | | IPv4 Global Address +----+----+ +----+----+ | CGN | | CGN | +----+----+ +----+----+ Any IPv4 Address | | Any IPv4 Address +----+----+ +----+----+ | CPE NAT | | CPE NAT | +----+----+ +----+----+ IPv4 Private Address | | IPv4 Private Address +----+----+ +----+----+ |IPv4 Host| |IPv4 Host| +---------+ +---------+ Shirasaki, et al. Expires April 30, 2009 [Page 3] Internet-Draft NAT444 with ISP Shared Address October 2008 3. Pros and Cons of NAT444 Model 3.1. Pros of NAT444 Model This network model has following advantages. - This is the only network model that doesn't require replacing CPEs those are owned by customers. - This network model is composed of the present technology. - This model doesn't require address family translation. - This model doesn't require DNS rewriting. 3.2. Cons of NAT444 Model This network model has some technical restrictions. - Some application such as SIP and FTP requires special treatment, because IP address is written in the payload of the packet. Special treatment means application itself aware double NAPT or both of two NAPTs support inspecting and rewriting the packets. - Because both IPv4 route and IPv6 route exist, it doubles the number of IGP route inside the CGN. - UPnP doesn't work with double NAPTs. 4. Address Block of ISP's Network The address block mentioned in this section is the one between CPE and CGN. The best address block is "ISP Shared Address" which is defined in [I-D.shirasaki-isp-shared-addr] and briefly described in this section. 4.1. Global Address ISP cannot assign IPv4 Global Address any more after the exhaustion. 4.2. Private Address It has two major problems. 4.2.1. Hairpining 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 Shirasaki, et al. Expires April 30, 2009 [Page 4] Internet-Draft NAT444 with ISP Shared Address October 2008 CGN, ISP has to use Policy Based Routing (PBR). 4.2.2. Address Block Duplication Issue The Private Address in ISP's network could conflict with its customer's network address. Most 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. 4.3. 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 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. 4.4. 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] 5. 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. 6. 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] 7. Security Considerations Each customer inside a CGN looks using the same Global Address. from outside an ISP. In case of incidents, the ISP must have the function to trace back the record of each customer's access without using only IP address. Shirasaki, et al. Expires April 30, 2009 [Page 5] Internet-Draft NAT444 with ISP Shared Address October 2008 If a Global Address of the CGN is listed on the blacklist, other customers who share the same address could be affected. 8. References 8.1. Normative References [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, February 1996. [RFC4925] Li, X., Dawkins, S., Ward, D., and A. Durand, "Softwire Problem Statement", RFC 4925, July 2007. [I-D.shirasaki-isp-shared-addr] Miyakawa, S., Nakagawa, A., Yamaguchi, J., and H. Ashida, "ISP Shared Address after IPv4 Address Exhaustion", draft-shirasaki-isp-shared-addr-00 (work in progress), June 2008. [I-D.nishitani-cgn] Nishitani, T. and S. Miyakawa, "Carrier Grade Network Address Translator (NAT) Behavioral Requirements for Unicast UDP, TCP and ICMP", draft-nishitani-cgn-00 (work in progress), July 2008. [I-D.wilson-class-e] Wilson, P., Michaelson, G., and G. Huston, "Redesignation of 240/4 from "Future Use" to "Private Use"", draft-wilson-class-e-02 (work in progress), September 2008. 8.2. Informative References [PROP58] Niinobe, S., Tomochika, T., Yamaguchi, J., Nishino, D., Ashida, H., Nakagawa, A., and T. Hosaka, "Proposal to create IPv4 shared use address space among LIRs", 2008, . Appendix A. Example IPv6 Transition Scenario The steps of IPv6 transition are as follows. Step 1: Enabling softwire client in host Shirasaki, et al. Expires April 30, 2009 [Page 6] Internet-Draft NAT444 with ISP Shared Address October 2008 ISP provides IPv6 connectivity to customers with softwire [RFC4925]. ISP installs CGN and softwire concentrator in its network. A softwire client in host connects to the IPv6 internet via ISP's concentrator. ISP can use existing IPv4 equipments. Customers can just use existing CPE. (The IPv4 Internet) (The IPv6 Internet) | | IPv6 | +-----------+-----------+ | | Softwire Concentrator | | +-----------+-----------+ +---------+----------+ ^ IPv4 Global Address | : +----------+----------+ : | CGN | : +----------+----------+ : IPv4 ISP Shared Address | : IPv6 over IPv4 Softwire (ISP Network) | : (e.g. IPv6 over IPv4 L2TP) +----------+----------+ : | IPv4 NAT only CPE | : +----------+----------+ : IPv4 Private Address | v +---------------+-----------------+ |IPv4/IPv6 Softwire Client in host| +---------------------------------+ Step 2: Enabling softwire client in CPE A customer enables softwire client in CPE. A softwire client in CPE connects to the IPv6 internet via ISP's concentrator. A Customer's network is now dual stack. Shirasaki, et al. Expires April 30, 2009 [Page 7] Internet-Draft NAT444 with ISP Shared Address October 2008 (The IPv4 Internet) (The IPv6 Internet) | | IPv6 | +----------+------------+ | | Softwire Concentrator | | +----------+------------+ +---------+------------+ ^ IPv4 Global Address | : +----------+------------+ : | CGN | : IPv6 over IPv4 Softwire +----------+------------+ : (e.g. IPv6 over IPv4 L2TP) IPv4 ISP Shared Address | : (ISP Network) | v +---------------+--------------------+ |IPv4 NAT/IPv6 Softwire client in CPE| +---------------+--------------------+ IPv4 Private Address / | IPv6 Dual Stack | +-----------+-------------+ |IPv4/IPv6 Dual Stack host| +-------------------------+ Step 3: Moving on to dual stack ISP provides dual stack access to CPE. A CPE uplink is now dual stack. (The IPv4 Internet) (The IPv6 Internet) | | +---------+ | IPv4 Global Address | | +--------+--------+ | | CGN | | IPv6 +--------+--------+ | IPv4 ISP Shared Address / | | IPv6 Dual Stack +-------------+ (ISP Network) | +---------------+----------------+ | IPv4 NAT/IPv6 Dual Stack CPE | +---------------+----------------+ IPv4 Private Address / | IPv6 Dual Stack | +-----------+-------------+ |IPv4/IPv6 Dual Stack host| +-------------------------+ Step 4: Moving on to pure IPv6 IPv6 transition completes. Shirasaki, et al. Expires April 30, 2009 [Page 8] Internet-Draft NAT444 with ISP Shared Address October 2008 (The IPv6 Internet) | IPv6 | +--------+----------+ | IPv6 CPE | +--------+----------+ IPv6 | +--------+----------+ | IPv6 host | +-------------------+ Appendix B. Example Architectures This section explains example architectures how to design NAT444 with ISP Shared Address. B.1. Direct Routing inside CGN This architecture enables direct communication between customers inside same CGN. It has the following advantages. - The packets don't go through CGN. (No hairpining) - The customers inside CGN can use bidirectional applications (e.g. TV Conference, VPN). - 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| +---------+ +---------+ Shirasaki, et al. Expires April 30, 2009 [Page 9] Internet-Draft NAT444 with ISP Shared Address October 2008 B.2. CGN Bypassing This architecture is bypassing the NAT function of CGN. It has the following advantage. - The customers inside an ISP can use bidirectional applications (e.g. TV Conference, VPN). -Any communication in single ISP doesn't consume CGN external port. -ISP's servers outside CGN can access CPE. (e.g. ICMP echo, SNMP, remote access) -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| +---------+ +---------+ B.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. - The ISP can put ISP Shared Address customer and Global Address customer in the same concentrator. - The packets don't go through CGN. (No hairpining) Shirasaki, et al. Expires April 30, 2009 [Page 10] Internet-Draft NAT444 with ISP Shared Address October 2008 - The customers inside CGN can use bidirectional applications (e.g. TV Conference, VPN). - 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| +-----------+ +---------+ Authors' Addresses Yasuhiro Shirasaki (editor) 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 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 Shirasaki, et al. Expires April 30, 2009 [Page 11] Internet-Draft NAT444 with ISP Shared Address October 2008 Akira Nakagawa KDDI CORPORATION GARDEN AIR TOWER, 3-10-10, Iidabashi, Chiyoda-ku Tokyo 102-8460 Japan Email: ai-nakagawa@kddi.com 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 Hiroyuki Ashida its communications Inc. 3-5-7 Hisamoto Takatsu-ku Kawasaki-shi Kanagawa 213-0011 Japan Email: ashida@itscom.ad.jp Shirasaki, et al. Expires April 30, 2009 [Page 12] Internet-Draft NAT444 with ISP Shared Address October 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Shirasaki, et al. Expires April 30, 2009 [Page 13]