Internet Engineering Task Force G. Chen Internet-Draft H. Deng Intended status: Informational China Mobile Expires: September 15, 2011 March 14, 2011 NAT64-CPE Mode Operation for Opening Residential Service draft-chen-v6ops-nat64-cpe-01 Abstract The document has proposed an approach of NAT64-CPE mode, which would give residential service opportunities to be accessed by remote subscribers going through IPv6 networks. The document captures the fundamental NAT64 Functionalities with special cares to fit into CPE scenarios and don't need cooperate with DNS64 any more. In addition, the CPE mode also allows IPv4 residential hosts to access IPv6 service. It will compatible with legacy residential hosts/servers and no further updates requirements to public DNS system. 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 September 15, 2011. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. 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. 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Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. NAT64-CPE Mode Scenario Overviews . . . . . . . . . . . . . . . 3 2.1. Communications between IPv6 hosts and IPv4 residential servers . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Communications between IPv6 servers and IPv4 residential hosts . . . . . . . . . . . . . . . . . . . . . 4 3. NAT64-CPE Mode Operation . . . . . . . . . . . . . . . . . . . 5 3.1. NAT64-CPE Operations for Scenario 1 . . . . . . . . . . . . 5 3.1.1. CPE Functionalities Description . . . . . . . . . . . . 5 3.1.2. DNS Configuration Consideration . . . . . . . . . . . . 6 3.1.3. NAT64-CPE Flow Example for Scenario 1 . . . . . . . . . 6 3.2. NAT64-CPE Operations for Scenario 2 . . . . . . . . . . . . 7 3.2.1. CPE Functionalities Description . . . . . . . . . . . . 7 3.2.2. NAT64-CPE Flow Example for Scenario 2 . . . . . . . . . 8 4. NAT64-CPE Approach Discussion . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 9 7. Informative References . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Chen & Deng Expires September 15, 2011 [Page 2] Internet-Draft NAT64-CPE March 2011 1. Introduction Recently,IPv6 transition is fairly prevalent due to the depletion of IPv4 soon enough. However, the large number of installed CPE is IPv4-only based and likely to remain for several years. Considering the existing deployment approaches, majority of ISP assigned private IPv4 address to their customers,including residential servers and hosts. The nature of private IPv4 would block the end-to-end bi- directional communications. On the other hand, the goal of Internet services is to offer users ubiquitous experiences. User will be certainly supposed to able to enjoy such conveniences regardless of where we are. Therefore, ISP would take advantage of the accessibilities of residential services to provide plenty of services. Fortunately, IPv6 will get ISP end-to-end benefits. During IPv6 migration period, NAT64-CPE mode could overcome the obstacles to achieve final goals. The document is aimed at proposing an approach of NAT64-CPE mode, which would give residential service opportunities to be accessed by remote subscribers going through IPv6 networks. The document captures the fundamental NAT64[NAT64] functionalities with special cares to fit into CPE scenarios. In these scenarios, the NAT64-CPE don't need cooperate with DNS64[DNS64] any more, whereby this mechanism allows an IPv6-only client (i.e. either a host with only IPv6 stack, or a host with both IPv4 and IPv6 stack, but only with IPv6 connectivity or a host running an IPv6 only application) to initiate communications to an IPv4-only residential service server. In addition, such CPE mode also allows IPv4 residential hosts to be capable of accessing IPv6 service. The packages generated by IPv4 hosts can be translated by NAT64-CPE, which will communicate with IPv6 servers. The document is structured as follows. Section 2 describes appropriate scenario the NAT64-CPE mode fit to. Section 3 enumerates various functional parts for NAT64-CPE operation. Section 4 focus on the benefits the NAT64-CPE could bring. Section 5 is further securities consideration. 2. NAT64-CPE Mode Scenario Overviews 2.1. Communications between IPv6 hosts and IPv4 residential servers Figure 1 illustrates a possible network scenario where an IPv6-only client attached to a dual-stack network, but the destination server is running on a private site where there is NAT64-CPE numbered with public IPv6 addresses and private IPv4 addresses. DNS is located in Chen & Deng Expires September 15, 2011 [Page 3] Internet-Draft NAT64-CPE March 2011 dual stack Internet for naming-resolving. +----------------------+ +------------------------------+ | Dual Stack Internet | | IPv4 Private site (Net 10) | | | | | | | | | | | | +----------+ | | +----+ +---------+ | | | | | H1 |-----------|NAT64-CPE|-------------| Server | | | +----+ +---------+ | | | | v6 only / | | +----------+ | | Host / | | IPv4-only | | +-----+ | | etc. 10.1.1.1 | | | DNS | | | | | +-----+ | | | +----------------------+ +------------------------------+ Figure 1: NAT64-CPE Network Scenario 1 This scenario appears in ISP network quite popular. As the instances, visitors go through distant network to take care of family affairs, like monitoring house security via residential camera, manipulating household appliances remotely prior to comeback home. 2.2. Communications between IPv6 servers and IPv4 residential hosts Figure 2 illustrates a possible network scenario where an IPv4-only client connects to NAT64-CPE , and the destination server is running in IPv6 network. DNS is located in IPv6 network for naming- resolving. NAT6-CPE will have DNS-ALG capabilities for resolving IPv4 DNS query. Chen & Deng Expires September 15, 2011 [Page 4] Internet-Draft NAT64-CPE March 2011 +----------------------+ +------------------------------+ | IPv6-only network | | IPv4 Private site (Net 10) | | | | | | | | | | | | +----------+ | | +--------+ +---------+ | | | | | Server |-------|NAT64-CPE|-------------| Host | | | +--------+ |(DNS-ALG)| | | | | v6 only /+---------+ +----------+ | | Server / | | IPv4-only | | +-----+ | | etc. 10.1.1.1 | | | DNS | | | | | +-----+ | | | +----------------------+ +------------------------------+ Figure 2: NAT64-CPE Network Scenario 2 This scenario could allow legacy IPv4 host to access IPv6 services. There are no additional requirements for IPv4 host. 3. NAT64-CPE Mode Operation The whole process of NAT64-CPE operation involves CPE, DNS and addressing mechanism. This section illustrates different parts of functionalities for each scenario. 3.1. NAT64-CPE Operations for Scenario 1 3.1.1. CPE Functionalities Description Two kinds of functions the NAT64-CPE would take on. First, it will perform the functionalities that normal CPE does except NAT44 forwarding, like assigning private IPv4 address to their attached residential servers. Additionally, CPE will allocate private IPv4 address to the servers depending on the server MAC address. Therefore, the server could always get constant private IPv4 address. Second, CPE should carry NAT64 capable mode without integrating DNS64. According to normative handing, NAT64-CPE translates in- coming IPv6 destination address by striping NAT64 IPv6-prefix and maintains a IPv4 pool for translating IPv6 sources address. Therein, the NAT64 IPv6 prefix will be NSP specified in IPv6 Addressing of IPv4/IPv6 Translators. And, ISP will reserve distinct NSP for each CPE. The prerequisite here is that NAT64-CPE should maintain address Chen & Deng Expires September 15, 2011 [Page 5] Internet-Draft NAT64-CPE March 2011 mapping between inner IP address and outer IP address. PCP [PCP] could handle such problems. But that goes beyond the scope of this draft. Also, NAT64-CPE would install ALG, but it is optional. 3.1.2. DNS Configuration Consideration Each residential services should be represented by FQDN format so as to users could easily remember and understand. The corresponding naming resource record should be stored as AAAA. The record's IPv6 address is synthesized by NAT64 prefix and private IPv4 address. The IPv6 format is compliant with assembling IPv6 address in DNS64. The deployed DNS just follow regular DNS handling. There are no demands for performing DNS64 process. 3.1.3. NAT64-CPE Flow Example for Scenario 1 Figure 3 demonstrates the NAT64-CPE Mode operation flow, in which IPv6 host initiate service interaction with residential server remotely. The detailed actions that different entities performed was described afterwards. IPv6-only Host DNS NAT64-CPE Server | | |IPv4 assigning | (1) | | |<- - - - - - - >| |AAAA query: | | | |household.cam| | | (2) |============>| | | |AAAA response| | | |2001::a01:101| | | (3) |<============| | | | IPv6 traffic | | (4) |------------------------->| | | | +-----------+ IPv4 | (5) | | | NAT64-CPE |--------->| | IPv6 traffic |translation| IPv4 | (6) |<-------------------| |<---------| | | +-----------+ | Figure 3: NAT64-CPE Flow Example for Scenario 1 (1) NAT64-CPE should be configured with NAT64 prefix, which is allocated by ISP. In that case, the NAT64 prefix is 2001::/64. NAT64-CPE assign private IPv4 address to the servers depending on the server MAC address. And, NAT64-CPE already has maintained the Chen & Deng Expires September 15, 2011 [Page 6] Internet-Draft NAT64-CPE March 2011 mapping between inner IP address and outer IP address. (2)IPv6-only host initiates AAAA query for resolving service name, for example, that is household.cam. (3)DNS response AAAA record to the previous query. The IPv6 address of this service is synthesized by NAT64 prefix and assigned private IPv4 address. That is 2001::a01:101 (4)IPv6-only host send IPv6 traffic targeting to 2001::a01:101. The IPv6 traffic is routed to CPE. (5)NAT64-CPE detects incoming IPv6 packets and algorithmically translated to IPv4 addresses by using the algorithm defined in [I-D.ietf-behave-address-format]. The translated IPv4 traffic is headed to IPv4-only residential server and perform somehow process. (6)The residential IPv4 server responses these requests by IPv4 traffic, which will be sent to CPE. CPE performes reversed algorithm to translate IPv4 to IPv6 based on the maintained mapping information. And then, CPE generate IPv6 traffic and transmit to IPv6-only Host. 3.2. NAT64-CPE Operations for Scenario 2 3.2.1. CPE Functionalities Description In this scenario, CPE is integrated with DNS-ALG, which will accept IPv4 DNS A query and translated into A and AAAA. After name- resolving is finished in IPv6 network, DNS-ALG take different actions according to DNS responses. o DNS response only contains AAAA response. DNS-ALG will translate AAAA into A response. Meanwhile, a private IPv4 is required to be assigned to DNS A response. while, NAT64-CPE creates corresponding IPv6->IPv4 mapping in NAT6-CPE. o DNS response contains AAAA and A response. DNS-ALG will return A response to IPv4 hosts. There are no additional states NAT64-CPE need to create. o DNS response only contains A response. DNS-ALG will return A response to IPv4 hosts. There are no additional states NAT64-CPE need to create. When IPv4 hosts get DNS responses through NAT64-CPE, it would create packets to communicate with remote servers. When the packet reaches the CPE box, CPE would recognize if the flow is belonging to existing Chen & Deng Expires September 15, 2011 [Page 7] Internet-Draft NAT64-CPE March 2011 IP address mapping by determining IPv4 destination address and port. if CPE found matching records in NAT cache, NAT64-CPE would assign IPv6 address and port to translate the tuple of (Source Address, Source TCP port). Otherwise, NAT64-CPE will do NAT44 forwarding. 3.2.2. NAT64-CPE Flow Example for Scenario 2 Figure 4 demostrates the NAT64-CPE Mode operation flow, in which Internal IPv4 host initiate service interaction with remote IPv6 server. IPv4-only +-----------------------+ Host |DNS ALG NAT64-CPE| DNS Server IPv6 server | +-----------------------+ | | | | | | | |A query: | | | | |ipv6.service | | | | (1) |============>| A & AAAA query:ipv6.services| | | |---------------------------->| | (3) | | AAAA response(2001::1) | | | |<----------------------------| | (4) | +--------+ | | | | |AAAA->A |------->| | | | +--------+ Create | | | |<------------| mapping| | | | A response | | | | | | | | | | | | | | | | +-----------+ IPv6 | | (5) |------------------->| NAT64-CPE |----------------------->| | IPv4 traffic |translation| IPv6 | | (6) |<-------------------| |<-----------------------| | | +-----------+ | | Figure 4: NAT64-CPE Flow Example for Scenario 2 4. NAT64-CPE Approach Discussion Considering above description, NAT64-CPE has following specific features. o NAT64-CPE is capable of making residential server to be accessed, by means of which users could visit the IPv4-only server remotely. Chen & Deng Expires September 15, 2011 [Page 8] Internet-Draft NAT64-CPE March 2011 o NAT64-CPE is a solely NAT64 deployed solution in CPE environment. It will compatible with legacy residential servers and no further updates requirements to DNS. Therefore, it's liable to be deployed. o NAT64-CPE allows legacy IPv4 hosts to access IPv6 service. There are no additional requirements for IPv4 hosts. 5. Security Considerations Essentially, there are strong demands to have thorough security mechanism to prevent privacy invasion in CPE scenario. The detailed considerations need to be further identified. 6. IANA Considerations This memo includes no request to IANA. 7. Informative References [DNS64] Bagnulo, M., "DNS64: DNS extensions for Network Address Translation from IPv6 Clients to IPv4 Servers", IETF Internet-draft draft-ietf-behave-dns64-10.txt, July 2010. [NAT64] Bagnulo, M., "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", draft-ietf-behave-v6v4-xlate-stateful-12.txt (work in progress), July 2010. [PCP] Wing, D., "Pinhole Control Protocol (PCP)", draft-ietf-pcp-base-06.txt (work in progress), February 2011. Authors' Addresses Gang Chen China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: chengang@chinamobile.com Chen & Deng Expires September 15, 2011 [Page 9] Internet-Draft NAT64-CPE March 2011 Hui Deng China Mobile 53A,Xibianmennei Ave. Beijing 100053 P.R.China Phone: +86-13910750201 Email: denghui02@gmail.com Chen & Deng Expires September 15, 2011 [Page 10]