Internet Engineering Task Force G. Chen Internet-Draft Z. Cao Intended status: Informational China Mobile Expires: August 17, 2012 C. Byrne T-Mobile USA Q. Niu ZTE February 14, 2012 NAT64 Operational Experiences draft-chen-v6ops-nat64-experience-00 Abstract This document summarizes some stateful NAT64 deployment scenarios and operational experiences for NAT64-CGN and NAT64-CE. 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 August 17, 2012. Copyright Notice Copyright (c) 2012 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. 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, et al. Expires August 17, 2012 [Page 1] Internet-Draft NAT64 Experience February 2012 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 Experiences . . . . . . . . . . . . . . . 3 2.1. NAT64-CGN Networking . . . . . . . . . . . . . . . . . . . 4 2.2. High Availability Consideration . . . . . . . . . . . . . 5 2.3. Traceability and Lawful Interception . . . . . . . . . . . 5 2.4. Quality of Experience . . . . . . . . . . . . . . . . . . 6 2.5. Load Balance . . . . . . . . . . . . . . . . . . . . . . . 6 3. NAT64-CE Deployment Experiences . . . . . . . . . . . . . . . 6 3.1. NAT64-CE Networking . . . . . . . . . . . . . . . . . . . 7 3.2. Anti-DDoS/SYN Flood . . . . . . . . . . . . . . . . . . . 8 3.3. User Behavior Analysis . . . . . . . . . . . . . . . . . . 8 3.4. DNS Resolving . . . . . . . . . . . . . . . . . . . . . . 8 3.5. Load Balance . . . . . . . . . . . . . . . . . . . . . . . 8 3.6. MTU Consideration . . . . . . . . . . . . . . . . . . . . 9 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.1. Normative References . . . . . . . . . . . . . . . . . . . 9 6.2. Informative References . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Chen, et al. Expires August 17, 2012 [Page 2] Internet-Draft NAT64 Experience February 2012 1. Introduction With fast developments of global Internet, the demands for IP addresses are rapidly increasing. IANA announced that the global IPv4 address pool has been exhausted on February 3, 2011. IPv6 is the only sustainable solution for numbering nodes on the Internet. Network operators have to accelerate the process of deploying IPv6 networks in order to meet the numbering needs of expanding internet without available IPv4 addresses. As IPv6 deployments progress, IPv6 will coexist with IPv4. The Internet will include nodes that are IPv4-only, IPv6-only, and nodes that are dual-stack with IPv4 and IPv6. The interconnection between IPv4-only nodes and IPv6-only nodes is a critical capability. Given that widespread dual-stack deployments have not materialized over the last 10 years for which the approach has been prescribed prior to IPv4 exhaust, it is obvious that NAT64[RFC6146] will be a key element of the going-forward internet infrastructure. Regarding the IPv4/IPv6 translation, RFC6144[RFC6144] has described a framework enabling networks to have IPv4 and IPv6 coexist. There are three common NAT64 deployment scenarios "An IPv6 Network to the IPv4 Internet", "The IPv6 Internet to an IPv4 Network" and "An IPv6 Network to an IPv4 Network". Since the scenario of "The IPv6 Internet to the IPv4 Internet" seems the ideal case for in-network translation technology, this document has focused on the three cases and categorized different NAT64 usages as NAT64-CGN and NAT64-CE. Therein, NAT64-CGN are corresponding to the scenario "IPv6 Network to IPv4 Internet". NAT64-CE is for "IPv6 Internet to IPv4 Network" and "IPv6 Network to IPv4 Network" respectively. Based on different NAT64 modes, different considerations have been elaborated for ISPs to facilitate NAT64 deployments. The purpose of this document is to summarize deployment experience of server operators and content providers regarding NAT64. The reader of this document can get the information for their possible deployment of NAT64 in future. Whether the audiences take the experience as their deployment guidance is up to them, not the purpose of this document. 2. NAT64-CGN Deployment Experiences The NAT64-CGN Scenario is depicted in Figure 1 Chen, et al. Expires August 17, 2012 [Page 3] Internet-Draft NAT64 Experience February 2012 ----------- ---------- // \\ // \\ / \ / +----+ \ | |XLAT| | | An IPv6 +----+ The IPv4 | | Network +----+ Internet | XLAT: IPv6/IPv4 | |DNS | | Translator \ +----+ / DNS: DNS64 \\ // \ / --------- \\ // ----------- ====> Figure 1: NAT64-CGN Scenario: IPv6 Network to IPv4 Internet 2.1. NAT64-CGN Networking NAT64-CGN case is focusing on connecting IPv6-only users with IPv4 Internet. NAT64 performs protocol translation from an IPv6 packet header to an IPv4 packet header and vice versa is performed according to the the Stateful NAT64 [RFC6146]. Address translation maps IPv6 addresses to IPv4 addresses and vice versa. Given that all IPv4 connections to the IPv4 Internet from IPv6-only clients must traverse the NAT64, the NAT64 should be located close to the IPv4 peering points to reduce unnecessary backhaul costs and latency. It is advantageous for troubleshooting and traffic engineering to maintain the IPv6 traffic native for as long as possible within an access network and only translate at the network border. Coming to a real practice in broadband access network, NAT64 functionalities could be located on BNG or core router depending on scale of IPv6-enable network. From implementation views, NAT64 functionalities could be served by either a dedicated GW or an existing GW integrated with NAT64 functionality. In standalone NAT64, NAT64-CGN is placed in a side of BNG or CR. The deployment has few impacts to a given network, which results in a low OPEX. On the other side, an embedded NAT64 is integrated with existing GW, it requires relative lower investment, i.e. lower CAPEX. However, capacities of existing GW would be restricted by the inserted functionality. It likely requires a new round of network planning, which would cause high OPEX. The different deployment modes would correspond to specific use cases, in which ISP should consider different perspectives, e.g. Chen, et al. Expires August 17, 2012 [Page 4] Internet-Draft NAT64 Experience February 2012 traffic model, investment, network evolution, etc. 2.2. High Availability Consideration High Availability (HA) is a major requirement for every service and network service. In general, there are two mechanisms to achieve high reliability, i.e. cold-standby and hot-standby. Cold-standby has synchronized configuration and mechanism to failover traffic between the hot and cold systems such as VRRP [RFC5798] . Unlike hot-standby, cold- standby does not synchronize NAT64 session state. This makes cold- stanby less resource intensive and generally simpler, but it requires clients to re-establish sessions when a fail-over occurs. Hot-stanby has all the features of cold-standby but must also synchronize the binding information base (BIB). Considering the most common Internet traffic type is short lived sessions, hot-standby does not offer much benefit unless long lived sessions are common and the cost is justified. 2.3. Traceability and Lawful Interception Traceability and Lawful Interception(LI) are required in many cases to identify an attacker or a host that was used to launch malicious attacks and/or for various other purposes of accounting. In order to facilitate traceability, NAT64 devices are required to log events like creation and deletion of translations and information about the occupied resources. There are two different demands for traceability,i.e. online or offline. Regarding the Online requierements, XFF (X-Forwarded-For) would be a candidate, it appends IPv6 address of subscribers to HTTP headers which is passed on to WEB servers, and the querier server can lookup radius servers for the target subscribers based on IPv6 addresses included in XFF HTTP headers. NAT64-CGN could also deliver NAT64 session (BIB and STE) to Radius server by some extent of radius protocol extension. That is an alternative solution for online traceability, but high performance is required on Radius servers . For off-line traceability, syslog might a good choice. Lawful intercept is normally part of the access network, in which an optical splitter is used to bypass all traffic for subsequent filtering process. It's not the requirement for NAT64. However, operators may expect to serve as interception access point (IAP) avoiding installation of additional LI system. It's low-cost and fast-deployed. It's an alternative solution for LI even if that may not a major case in current practices. Chen, et al. Expires August 17, 2012 [Page 5] Internet-Draft NAT64 Experience February 2012 2.4. Quality of Experience While NAT64 is bridge between the IPv6 and IPv4, it is important that the NAT64-CGN have the appropriet ALGs to support customers, e.g. FTP-ALG[RFC6384], SIP-ALG, RSTP-ALG, H.323-ALG, SCCP-ALG, and PPTP- ALG. At the same time, it is also important to remind customers that IPv6 end-to-end does not required ALGs and therefore that provides the best experience. The service experiences also should be optimized in context of stateful NAT64, which has some common issues regarding NAT process. To be specific, session status normally is managed by a static lifetime cycle. In some cases, NAT resource maybe suffered from significant inactive users. A flexible NAT session control is desirable to resolve the issues. PCP[I-D.ietf-pcp-base] could be a candidate to provide such capability. In the case, NAT64-CGN should integrate with PCP server, depending on which available IPv4 address/ Port could be assigned to PCP client through PCP MAP/PEER mode. Such abilities should also be considered to upgrade user experiences, e.g. assigning different sizes of port ranges for different subscribers. 2.5. Load Balance Load balance is an essential ability to avoid the issue of single point of failure and add the feature of linear scalability. When there are multiple NAT64 CGN deployed, it is important to achieve load balancing between these different devices. [I-D.zhang-behave-nat64-load-balancing] discusses several ways of achieving NAT64 load balancing, including anycast based policy and prefix64 selection based policy, either implemented via DNS64 or Prefix64 assignments. 3. NAT64-CE Deployment Experiences The NAT64-CE Scenario is depicted in Figure 2 Chen, et al. Expires August 17, 2012 [Page 6] Internet-Draft NAT64 Experience February 2012 -------- // \\ ---------- / \ // \\ / +----+ \ | |XLAT| | | The IPv6 +----+ An IPv4 | | Internet +----+ Network | XLAT: IPv4/IPv6 | /Network |DNS | | Translator \ +----+ / DNS: DNS64 \ / \\ // \\ // ---------- -------- ====> Figure 2: NAT64-CE Scenario: IPv6 Internet/Network to IPv4 Network 3.1. NAT64-CE Networking More and more contents providers would like to use IPv6 to serve customers since it allows for the definition of new services without having to backward integrate into the NATs and address limitations of IPv4 networks. Cloud computing is growing, which requires millions of public addresses. IPv6 could provide a good opportunity to meet the deployment requirements by subsiding the location to a customer edge, e.g. Enterprise-GW. On the other side, residential facilities is always going out of ISP control. It's hard to guarantee positioned network device or installed applications are IPv6-capable. Thereby, NAT64 on CPE could easily help homenet become IPv6- reachable. 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. One big challenge for NAT64-CE is IPv6 space always much bigger than IPv4 space. When increasingly numerous users in IPv6 Internet access an IPv4 network, there will be not enough IPv4 addresses and/or ports to serve the mapping. One potential solution is to distributed NAT64-CE at separated CE domain. Each domain could reuse the IPv4 address defined in RFC1918 [RFC1918], which would expand IPv4 spaces by increasing reuse ratio of IPv4 address. Note: considering this challenge of NAT64, it is suggested that NAT64-CE is only deployed and used in the scenario for small scale content providers and residential network where the incoming connections from the IPv6 Internet is not too many to destroy the NAT64 functionalities. Chen, et al. Expires August 17, 2012 [Page 7] Internet-Draft NAT64 Experience February 2012 3.2. Anti-DDoS/SYN Flood Without Anti-DDoS mechanism, the NAT64 is exposed to attacks from the IPv6 Internet which will greatly influence the user experience. Essentially, there are strong demands to have thorough security mechanism to prevent privacy invasion in NAT64-CE scenario. With service provisioning, potential safety hazard could also deteriorate service quality. for example, DDoS will severely degrade web performance. Security domain division is necessary in this case, especially for NAT64-CE in enterprise network. One practices in some ICP is place a L3 load balancer with capable of 10G line rate DDoS defense, like SYN Flood with SYN PROXY-COOKIE. Load Balancer could not only serve for optimization of traffic distribution, but also take filtering helping enhanment of security. 3.3. User Behavior Analysis The mapping information on the NAT64-CE is valuable for those who deploy it. Owners or operators of NAT64-CE could use the mapping and logging information for use behavior and preference analysis, and acurate advertisement delivery. Different ways of achieving user analysis may be applied. The NAT64-CE owner can either synchronize the mapping information with its local analysis engine or deploy delicated address mapping rules on the CE so that the orginal address information could be kept. 3.4. DNS Resolving In the case of NAT64-CE, it is recommended to follow the recommendations in [RFC6144]. There is no need for the DNS to synthesize AAAA from A records, since static AAAA records can be registered in the regular DNS to represent these IPv4-only hosts. How to design the FQDN for the IPv6 service is out-of-scope of this document. 3.5. Load Balance Load balance on NAT64-CE was twofold. First off, traffic should be balanced among multiple NAT64-CE devices, which has identical requirement with NAT64-CGN. One point should be noticed that a synthetic AAAA records may be added directly in authoritative DNS. The load balance based on DNS64 may not work in that cases. Secondly, NAT64-CE could also serve traffic distribution for IPv4 backend servers. There are also some ways of load balance for the cases , where the user placed NAT66 before the NAT64 so that the load balancer can be implemented at the NAT66 for any user preference policies. Chen, et al. Expires August 17, 2012 [Page 8] Internet-Draft NAT64 Experience February 2012 3.6. MTU Consideration IPv6 requires that every link in the internet have an MTU of 1280 octets or greater[RFC2460]. However, the coexistence with IPv4 link may let originating IPv6 node to receive an ICMP Packet Too Big message reporting a Next-Hop MTU less than 1280. That would result the IPv6 allows packets to contain a fragment header, without the packet being actually fragmented into multiple pieces. There is an analysis[I-D.gont-6man-ipv6-atomic-fragments] describing fragmentation-based security issues caused by such "atomic" fragments. One approach avoding this issue is to configure IPv4 MTU>=1260, which would forbid the occurence of PTB<1280. 4. Security Considerations This document only presents the deployment experiences of NAT64 in CGN and CE scenario, some security considerations have been considerated regarding to specific NAT64 mode in section 2 and 3. In general, RFC 6146[RFC6146] provides TCP-tracking, Endpoint-dependent filtering mechanisms to protect NAT64 from DDOS. In NAT64-CGN cases, ISP also could adopt uRPF and black/white-list to enhance the security by specifying access policies. for example, NAT64-CGN should forbid establish NAT64 BIB for incoming IPv6 packets if URPF (Strict or Loose mode) check does not pass or whose source IPv6 address is associated to black-lists. 5. IANA Considerations This memo includes no request to IANA. 6. References 6.1. Normative References [I-D.ietf-pcp-base] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", draft-ietf-pcp-base-23 (work in progress), February 2012. [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, February 1996. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. Chen, et al. Expires August 17, 2012 [Page 9] Internet-Draft NAT64 Experience February 2012 [RFC5798] Nadas, S., "Virtual Router Redundancy Protocol (VRRP) Version 3 for IPv4 and IPv6", RFC 5798, March 2010. [RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for IPv4/IPv6 Translation", RFC 6144, 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. [RFC6384] van Beijnum, I., "An FTP Application Layer Gateway (ALG) for IPv6-to-IPv4 Translation", RFC 6384, October 2011. 6.2. Informative References [I-D.gont-6man-ipv6-atomic-fragments] Gont, F., "Processing of IPv6 "atomic" fragments", draft-gont-6man-ipv6-atomic-fragments-00 (work in progress), December 2011. [I-D.zhang-behave-nat64-load-balancing] Zhang, D., Xu, X., and M. Boucadair, "Considerations on NAT64 Load-Balancing", draft-zhang-behave-nat64-load-balancing-03 (work in progress), July 2011. Authors' Addresses Gang Chen China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: chengang@chinamobile.com Zhen Cao China Mobile 53A,Xibianmennei Ave., Xuanwu District, Beijing 100053 China Email: caozhen@chinamobile.com Chen, et al. Expires August 17, 2012 [Page 10] Internet-Draft NAT64 Experience February 2012 Cameron Byrne T-Mobile USA Bellevue Washington 98105 USA Email: cameron.byrne@t-mobile.com QiBo Niu ZTE 50,RuanJian Road. YuHua District, Nan Jing 210012 China Email: niu.qibo@zte.com Chen, et al. Expires August 17, 2012 [Page 11]