Network Working Group C. Xie Internet-Draft Q. Sun Intended status: Standards Track Q. He Expires: January 30, 2014 China Telecom C. Zhou Huawei Technologies X. Li C. Bao CERNET Center/Tsinghua University July 29, 2013 The Approach for IPv4-only users to access IPv6-only Content draft-sun-behave-v4tov6-01 Abstract Current approaches can not solve the scenario that the users from IPv4 Internet to access IPv6-only content. When IPv6 content are becoming more and more popular, it is important to ensure that IPv6- only content can be reachable from legacy IPv4-only clients via some IPv4-only network. This document proposes two approaches for IPv4- only users to access IPv6-only content. It is designed to cover the Scenario 2 in [RFC6144]. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on January 30, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. Xie, et al. Expires January 30, 2014 [Page 1] Internet-Draft IPv4 user to access IPv6 Content July 2013 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. The NAT46 translator for IPv4 Internet to access IPv6 network . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Approach 1: DNS-based solution . . . . . . . . . . . . . . . . 4 5. Approach 2: Redirect-based Solution . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8.1. Normative References . . . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Xie, et al. Expires January 30, 2014 [Page 2] Internet-Draft IPv4 user to access IPv6 Content July 2013 1. Introduction In [RFC6144], Scenario 2 is an important use case. Not only could servers move directly to IPv6 without trudging through a difficult transition period, but they could do so without risk of losing connectivity with the IPv4-only Internet. Existing solutions have not solved this scenario well. NAT- PT[RFC2766]can be used in this scenario, but it requires a tightly coupled DNS Application Level Gateway (ALG) in the translator, and have been deprecated by the IETF [RFC4966]. The stateless translation solution [RFC6219] can work too, but since each IPv6 server will consume one IPv4 public address, it is not suitable to deploy in situation that operators are running out of IPv4 address. [RFC6156] can be used for IPv4 client to communicate with IPv6 client. But this requires the IPv4 client and IPv6 client to implement a TURN client. Therefore, it is not suitable for C-S(Client-Server) and B-S (Browser-Server) mode. [I-D.rfvlb-behave-v6-content-for-v4-clients] can work for IPv4-only user to access IPv6 content. But since it uses private IPv4 address to mapping the IPv6 server, it can only be used for IPv4 network to reach IPv6 network. This document is designed for IPv4 Internet to reach IPv6 network. There are several requirements in this design: 1.Considering IPv4 address has been a scarce resource, the amount of public IPv4 addresses consumed by the translator should be less than that the number of IPv6 servers in the IPv6 network. 2. It should not require extra modifications on the server, e.g. by using a dynamic port number, implementing TURN client, etc. In this document, we propose two approaches for this scenario. These two approaches can make use of existing DNS architecture. The binding table in these two approaches are static. Therefore, there will be no dynamic issue as in NAT-PT or DNS cache syncronization. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Terminology defined in [RFC6144] is used extensively in this document. Besides, this document uses the following terminologies: Xie, et al. Expires January 30, 2014 [Page 3] Internet-Draft IPv4 user to access IPv6 Content July 2013 IPv6-converted addresses: IPv4 addresses used to represent IPv6 nodes in an IPv4 Internet. They have an explicit mapping relationship to IPv6 addresses. NAT46: a stateful IPv4/IPv6 translation functionality. It is consistent with IP/ICMP translation [RFC6145], and can also support IPv6-converted address selection and binding table maintenance. 3. The NAT46 translator for IPv4 Internet to access IPv6 network The NAT46 solution is used for IPv4 clients in IPv4 Internet to reach IPv6 servers (depicted in Figure 1). ------- ------ // \\ Address Pool: // \\ / \ {210.0.0.0/20, / \ 23.0.0.1 | | 213.0.1.0/18...} | | 2001:c61::1 +---------+ | The IPv4 | +-----------------+ | The IPv6 | +--------+ | IPv4 | | Internet | | Translator | | Network | | IPv6 | | Client |--+ +-| (NAT46) |----+ +--| Server | +---------+ | | +-----------------+ | | +--------+ \ / Prefix:2001:c68::/96 \ / \\ // \\ // ------- ------ Figure 1: Overall solution for IPv4 Internet to IPv6 network In order to achieve the translation initiated from IPv4 side, two addresses need to be determined by NAT46 translator. The first one is the IPv6-converted address of the IPv6 server, which is is selected from the IPv4 address pool configured in NAT46. The second one is the IPv4-converted address for the IPv4 client, which can be synthetized using the stateless approach defined in [RFC6052]. In our approach, the mapping relationship between IPv6-converted address and the IPv6 address for the server is pre-determined in advance. As a result, the A record in the DNS server for a particular server is always the same for different IPv4 clients. 4. Approach 1: DNS-based solution This approach is independent of translated protocol. For applications without DNS process can not be solved by this approach. In order to support IPv4 address sharing for multiple IPv6 servers, one IPv4 address can be shared by multiple servers with different service ports. If there are too many servers with the same service Xie, et al. Expires January 30, 2014 [Page 4] Internet-Draft IPv4 user to access IPv6 Content July 2013 port, the second approach can be used as a complement. The overall solution is depicted in Figure 3. ------- +---------------+ ------ // \\ | +-----------+ | // \\ / \ | | DNS | | / \ +---------+ | The IPv4 | | +-----------+ | | The IPv6 | +--------+ | IPv4 | | Internet | | | | Network | | IPv6 | | Client |--+ +-| +--------+ |--+ +--| Server | +---------+ | | | | NAT46 | | | | +--------+ \ / | +--------+ | \ / \\ // +---------------+ \\ // ------- ------ Figure 2: DNS-based approach It consists of several functionalities: 1.NAT46: This functionality achieves the translation between IPv4 packet and IPv6 packet. It is consistent with [RFC6145]. Besides, it maintained the binding table including the IPv6 server address, IPv6-converted address for IPv6 server, and the service port statically. 2.DNS: The DNS server is configured with the IPv6-converted address as the A record for IPv6 server. The workflow of this apporach is as follows: +--------+ +--------+ +--------+ +--------+ | IPv4 | | DNS | | NAT46 | | IPv6 | | Client | | | | | | Server | +--------+ +--------+ +--------+ +--------+ | | | | |DNS A record query| | | | ipv6.example.com | | | |----------------->| | | | | | | | return A record | | | |<-----------------| | | | IPv4 traffic | Lookup the | |----------------------------------->| Binding Table | | | IPv6 Traffic | | |-------------->| | IPv4 traffic(Returned) |<--------------| |<-----------------------------------| | Xie, et al. Expires January 30, 2014 [Page 5] Internet-Draft IPv4 user to access IPv6 Content July 2013 Figure 3: Workflow of DNS-based approach 1. An IPv4 client initiates a DNS query for A record (e.g. ipv6.example.com). 2. DNS receives the query. As it is configured with the IPv6- converted address in advance, the A record will be returned to the IPv4 client. 3. IPv4 client sends IPv4 traffic with the returned IPv6-converted address as the destination address. 4. When the IPv4 traffic arrives at the NAT46, NAT46 extracts the destination address and destination port in the IPv4 traffic. It will lookup the binding table maintained in NAT46 and NAT46 translates the IPv4 packet to IPv6 packet according to [RFC6145]. No port translation will be performed here. 5. The return traffic is treated in the same way. 5. Approach 2: Redirect-based Solution This approach is designed for HTTP application. It will have a high address sharing ratio. In HTTP, since the traffic can be redirected to a different service port, it is able to achieve address sharing for IPv6 servers by using different ports (denoted as IPv6-converted port). Therefore, one IPv4 address can support up to thousands of IPv6 servers in theory. The overall solution is depicted in Figure 4. ------- +--------------------+ ------ // \\ | +----------------+ | // \\ / \ | |Redirect Server | | / \ +---------+ | The IPv4 | | +----------------+ | | The IPv6 | +--------+ | IPv4 | | Internet | | | | Network | | IPv6 | | Client |--+ +-| +------------+ |--+ +--| Server | +---------+ | | | | NAT46 | | | | +--------+ \ / | +------------+ | \ / \\ // +--------------------+ \\ // ------- ------ Figure 4: Redirect-based Solution It consists of several functionalities: 1. NAT46: This functionality is basically the same as the first Xie, et al. Expires January 30, 2014 [Page 6] Internet-Draft IPv4 user to access IPv6 Content July 2013 approach, except for the binding table includes IPv6 server address, IPv6 service port, IPv6-converted address and IPv6-converted port. 2. Redirect Server: A Redirect server is used to redirect traffic to a different IPv6-converted address and IPv6-converted port. The redirect server may either store the binding table, or query for the redirected address and port from NAT46. The workflow of this apporach is as follows: +--------+ +--------+ +--------+ +--------+ +--------+ | IPv4 | | DNS | |Redirect| | NAT46 | | IPv6 | | Client | | | | Server | | | | Server | +--------+ +--------+ +--------+ +--------+ +--------+ | | | | | | DNS A request | | | | | ipv6.example.com | | | | |----------------->| | | | | A response with | | | | | Redirect Ser Addr| | | | |<-----------------| | | | | HTTP GET request, with domain name | | | | in HOST field | Request for | | |----------------------------------->| IPv4 Dst Addr | Setup mapping | | |-------------->| table | |return 302 not found, carry IPv4 dst| | | |addr in HTTP redirect packet | | | |<-----------------------------------| | | | IPv4 HTTP request with new v4 dst addr | | |--------------------------------------------------->| Translate to IPv6 | | |------------------>| | |<------------------| |<---------------------------------------------------| | Figure 5: Workflow of Proxy-lite Approach 1. An IPv4 client initiates a DNS query for A record (e.g. ipv6.example.com). 2. In DNS server, the address of the redirect server is configured as the A record for ipv6.example.com and returns to the IPv4 client. 3. The IPv4 client sends HTTP GET request. The domain name (e.g. ipv6.example.com) is carried in HOST field. 4. The redirect server interprets the domain name, and sends the request to get IPv6-converted address to NAT46 (carrying the address Xie, et al. Expires January 30, 2014 [Page 7] Internet-Draft IPv4 user to access IPv6 Content July 2013 of IPv4 client and the destination port). The specific protocol for the request is now out of scope. 5. NAT46 selects IPv6-converted address and IPv6-converted port by lookuping the binding table. It will also keep the destination port in the binding table. 6. NAT46 returns the IPv6-converted address and IPv6-converted port to redirect server and the redirect server in turn returns IPv6- converted address in HTTP redirect packet with HTTP error "302 not found". 7. IPv4 client replaces the destination IPv4 address with the returned IPv6-converted address. The IPv4 traffic is routed to the NAT46. 8. extracts the destination address and destination port in the IPv4 traffic. It will lookup the binding table maintained in NAT46 and NAT46 translates the IPv4 packet to IPv6 packet according to [RFC6145]. 6. IANA Considerations No requirement on IANA. 7. Acknowledgements The authors would like to thank Dan Wing, Fred Baker for their review and comments. 8. References 8.1. Normative References [I-D.rfvlb-behave-v6-content-for-v4-clients] Rajtar, B., Farrer, I., Ales, V., Li, X., and C. Bao, "Framework for accessing IPv6 content for IPv4-only clients", draft-rfvlb-behave-v6-content-for-v4-clients-01 (work in progress), July 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2766] Tsirtsis, G. and P. Srisuresh, "Network Address Translation - Protocol Translation (NAT-PT)", RFC 2766, Xie, et al. Expires January 30, 2014 [Page 8] Internet-Draft IPv4 user to access IPv6 Content July 2013 February 2000. [RFC4966] Aoun, C. and E. Davies, "Reasons to Move the Network Address Translator - Protocol Translator (NAT-PT) to Historic Status", RFC 4966, July 2007. [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, October 2010. [RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for IPv4/IPv6 Translation", RFC 6144, April 2011. [RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation Algorithm", RFC 6145, April 2011. [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", RFC 6146, April 2011. [RFC6156] Camarillo, G., Novo, O., and S. Perreault, "Traversal Using Relays around NAT (TURN) Extension for IPv6", RFC 6156, April 2011. [RFC6219] Li, X., Bao, C., Chen, M., Zhang, H., and J. Wu, "The China Education and Research Network (CERNET) IVI Translation Design and Deployment for the IPv4/IPv6 Coexistence and Transition", RFC 6219, May 2011. 8.2. Informative References Authors' Addresses Chongfeng Xie China Telecom P.R.China Phone: 86 10 58552116 Email: xiechf@ctbri.com.cn Xie, et al. Expires January 30, 2014 [Page 9] Internet-Draft IPv4 user to access IPv6 Content July 2013 Qiong Sun China Telecom P.R.China Phone: 86 10 58552936 Email: sunqiong@ctbri.com.cn Qi He China Telecom P.R.China Phone: 86 10 58552332 Email: heqi@ctbri.com.cn Cathy Zhou Huawei Technologies Bantian, Longgang District Shenzhen 518129 P.R. China Phone: Email: cathy.zhou@huawei.com Xing Li CERNET Center/Tsinghua University Room 225, Main Building Beijing 100084 P.R.China Phone: +86 10 6278 5983 Email: xing@cernet.edu.cn Congxiao Bao CERNET Center/Tsinghua University Room 225, Main Building Beijing 100084 P.R.China Phone: +86 10 6278 5983 Email: congxiao@cernet.edu.cn Xie, et al. Expires January 30, 2014 [Page 10]