Internet Engineering Task Force G. Chen Internet-Draft China Mobile Intended status: Informational Oct 2011 Expires: April 3, 2012 NAT64 Operational Considerations draft-chen-v6ops-nat64-cpe-03 Abstract The document has summarized NAT64 usages on different modes, in which NAT64 may serve for a large-scale network or would give enterprise or residential service opportunities to be accessed by IPv6 remote subscribers. The document has described different operations for each usage and proposed operational considerations for each particular NAT64-mode. 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/. 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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 Chen Expires April 3, 2012 [Page 1] Internet-Draft NAT64 Oct 2011 described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. NAT64-CGN Deployment . . . . . . . . . . . . . . . . . . . . . 3 2.1. Deployment in IDC . . . . . . . . . . . . . . . . . . . . . 3 2.2. Connecting with IPv4 Internet . . . . . . . . . . . . . . . 4 2.3. NAT64-CGN Mode Requirements . . . . . . . . . . . . . . . . 5 3. NAT64-CE Mode . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. NAT64 at Enterprise Network Edge . . . . . . . . . . . . . 6 3.2. NAT64 at Residential Network Edge . . . . . . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 6. Normative References . . . . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8 Chen Expires April 3, 2012 [Page 2] Internet-Draft NAT64 Oct 2011 1. Introduction With fast developments of global Internet, the demands for IP address are rapidly increasing at present.This year, IANA announced that the global free pool of IPv4 depleted on 3 February. IPv6 is the only real option on the table. Operators have to accelerate the process of deploying IPv6 networks in order to address IP address strains.IPv6 deployment normally involves a step-wise approach where parts of the network should properly updated gradually. As IPv6 deployment progresses it may be simpler for operators and ICP/ISP to employ NAT64[RFC6146] functionalities at edge of IPv4 and IPv6 networks, since a significant part of network will still stay in IPv4 for long time. Especially, NAT64 could facilitate large ICP/ISP IPv6 transition process by eliminating upgrations of tremendous legacy IPv4 servers. Therefore, it's quite popular to deploy NAT64 at the front of IDC to shift the entire service to be IPv6-enable. Depending on different usage, NAT64 could be deployed on different places. The document has summarized NAT64 usages on different modes. Considering the existing deployment approaches, the memo has proposed different operational consideration for each particular NAT64-mode. 2. NAT64-CGN Deployment 2.1. Deployment in IDC NAT has widely used in data center environments whenever IDC have to make your IPv4-only content available to IPv6 clients. Figure 1 illustrates the usage where an IPv6-only host would like to initiate communications with IDC in IPv4 domain through NAT64. The NAT64 would accept IPv6 incoming session and distribute them to multiple IPv4 servers. Chen Expires April 3, 2012 [Page 3] Internet-Draft NAT64 Oct 2011 +----------------------+ +------------------------------+ | IPv6-only network | | IPv4 IDC | | | | | | | | | | | | +----------+ | | +----+ +---------+ | | | | | H1 |-----------| NAT64 |-------------| Servers | | | +----+ +---------+ | | | | v6 only / | | \ +----------+ | | Host / | | \ IPv4-only | | +------+ | | +-----+ | | |DNS64 | | | | DNS | | | +------+ | | +-----+ | +----------------------+ +------------------------------+ Figure 1: NAT64-CGN Mode Usage NAT64 device in IDC may also take responsibilities of load balancer, which can accept incoming TCP/UDP sessions on a single virtual IPv6 interface or multiple IPv6 interfaces. Afterwards, it distributes them according to a specific algorithm it uses to multiple IPv4 servers. Ideally you could have a mix of IPv4 and IPv6 servers sitting behind the virtual IPv6 address. Therein, NAT64 has to pick a new source IPv4 address and associated port number from local IPv4 address pool. DNS64 is a logical function that synthesizes DNS resource records(e.g., AAAA records containing IPv6 addresses) from DNS resource records actually contained in the DNS (e.g., A records containing IPv4 addresses). 2.2. Connecting with IPv4 Internet NAT64 may also be used to connecting IPv6 users with IPv4 Internet. In this cases, NAT64 could colocated with BNG or Core Router to map legacy IPv4 servers into a NAT64 prefix and performs 6-to-4 address. Therein, NAT64 would perform protocol translation mechanism and address translation mechanism. Protocol translation from an IPv4 packet header to an IPv6 packet header and vice versa is performed according to the IP/ICMP Translation Algorithm [RFC6145]. Address translation maps IPv6 transport addresses to IPv4 transport addresses and vice versa. Following illustrates normal process for this usage. Chen Expires April 3, 2012 [Page 4] Internet-Draft NAT64 Oct 2011 o Step1: IPv6-only host performs an AAAA DNS query to DNS64 for the IPv6 address of the Pv4-only sever. o Step2: DNS64 could not find the IPv6 address of the IPv4-only sever. So it tries to get the IPv4 address of the Pv4-only sever by sending A DNS query to DNS4. o Step3: DNS4 return the A record to the DNS64. o Step4: DNS64 map the IPv4 address to IPv6 address and send a synthetic AAAA record which is translated from A record to IPv6- only host. o Step5: IPv6-only host send the IPv6 packet to the NAT64. NAT64 translates the IPv6 packet to IPv4 packet and send it to IPv4-only server. 2.3. NAT64-CGN Mode Requirements According to above description for NAT64-CGN, the NAT64-CGN requirements are listed as following. NAT64-CGN-R1: Each NAT64 device MUST have at least one unicast IPv6 prefix assigned to it, denoted Pref64::/n. NAT64-CGN-R2:A NAT64 MUST have one or more unicast IPv4 addresses assigned to it. NAT64-CGN-R3:Irrespective of the transport protocol used, the NAT64 MUST silently discard all incoming IPv6 packets containing a source address that contains the Pref64::/n. NAT64-CGN-R4:The NAT64 MUST only process incoming IPv6 packets that contain a destination address that contains Pref64::/n. Likewise, the NAT64 MUST only process incoming IPv4 packets that contain a destination address that belongs to the IPv4 pool assigned to the NAT64. NAT64-CGN-R5:NAT64 MUST support the algorithm for generating IPv6 representations of IPv4 addresses defined in RFC6052 as Address Translation Algorithms. NAT64-CGN-R6:For incoming packets carrying TCP or UDP fragments with a non-zero checksum, NAT64 MAY elect to queue the fragments as they arrive and translate all fragments at the same time. NAT64-CGN-R7: For incoming IPv4 packets carrying UDP packets with a zero checksum, if the NAT64 has enough resources, the NAT64 MUST Chen Expires April 3, 2012 [Page 5] Internet-Draft NAT64 Oct 2011 reassemble the packets and MUST calculate the checksum. If the NAT64 does not have enough resources, then it MUST silently discard the packets. NAT64-CGN-R8: The NAT64 MAY require that the UDP, TCP, or ICMP header be completely contained within the fragment that contains fragment offset equal to zero. NAT64-CGN-R9:The NAT64 MUST limit the amount of resources devoted to the storage of fragmented packets in order to protect from DoS attacks. NAT64-CGN-R10:The NAT64 MUST make fragmentation process when MTU of incoming IPv4 traffic exceed maximum MTU on IPv6 side. NAT64-CGN-R11:The NAT64 MAY let hosts and applications know IPv6 prefix used by the NAT64 and DNS64 so as to hosts have knowledge whether synthetic IPv6 address is targeted. NAT64-CGN-R12:The NAT64 MAY decouple with DNS64 in order to establish communication with IPv4-only servers. NAT64-CGN-R13:The NAT64 MAY take load-balancing functionalities incorporating with DNS64. 3. NAT64-CE Mode NAT64-CE mode represents usages where there NAT64 is closed to customer edges, like enterprise network edge or residential network edge. 3.1. NAT64 at Enterprise Network Edge Some enterprise would like to offers their employees with IPv6 access. However, the service may still stay in IPv4 domain. NAT64 useges in enterprise network could help shift all enterprise service to be IPv6 enable. Figure 2 illustrates a network usage 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-CE numbered with public IPv6 addresses and private IPv4 addresses. Chen Expires April 3, 2012 [Page 6] Internet-Draft NAT64 Oct 2011 +----------------------+ +------------------------------+ | Dual Stack Internet | | IPv4 Private site (Net 10) | | | | | | | | | | | | +----------+ | | +----+ +---------+ | | | | | H1 |-----------|NAT64-CE |-------------| Server | | | +----+ +---------+ | | | | v6 only / | | +----------+ | | Host / | | IPv4-only | | +-----+ | | etc. 10.1.1.1 | | | DNS | | | | | +-----+ | | | +----------------------+ +------------------------------+ Figure 2: NAT64-CPE Mode Usage 3.2. NAT64 at Residential Network Edge Residential servers are usually going beyond the operator's management. They may not able to IPv6-enable due to limitations of application supporting. In this case, ISP is still assigning private IPv4 address to servers. However, The nature of private IPv4 would block the end-to-end bi-directional communications. On the other hand, IPv6 will bring end-to-end benefits to operators. NAT64-CPE mode could let IPv6 users to access such IPv6-disable services in residential areas. This scenario may appears in ISP network for several cases. 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. 4. Security Considerations Essentially, there are strong demands to have thorough security mechanism to prevent privacy invasion in NAT64-CPE scenario. The detailed considerations need to be further identified. 5. IANA Considerations This memo includes no request to IANA. Chen Expires April 3, 2012 [Page 7] Internet-Draft NAT64 Oct 2011 6. Normative References [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. [RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van Beijnum, "DNS64: DNS Extensions for Network Address Translation from IPv6 Clients to IPv4 Servers", RFC 6147, April 2011. [RFC6204] Singh, H., Beebee, W., Donley, C., Stark, B., and O. Troan, "Basic Requirements for IPv6 Customer Edge Routers", RFC 6204, April 2011. Author's Address Gang Chen China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: chengang@chinamobile.com Chen Expires April 3, 2012 [Page 8]