IPv6 Operations Working Group G. Lencse Internet Draft BUTE Intended status: Informational J. Palet Martinez Expires: April 2018 The IPv6 Company L. Howard Retevia R. Patterson Sky UK October 22, 2018 Pros and Cons of IPv6 Transition Technologies for IPv4aaS draft-lmhp-v6ops-transition-comparison-01.txt Abstract Several IPv6 transition technologies can be used to provide IPv4-as- a-service (IPv4aaS) to the customers, while the ISPs have only IPv6 in their access and or core network. All these technologies have their advantages and disadvantages. Depending on several various conditions and preferences, different technologies may prove to be the most appropriate solution. This document examines the five most prominent IPv4aaS technologies considering several different aspects in order to provide network operators with an easy to use guideline for selecting the technology that suit their needs the best. 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), 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 Lencse et al. Expires April 22, 2019 [Page 1] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 This Internet-Draft will expire on April 22, 2019. Copyright Notice Copyright (c) 2018 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 described in the Simplified BSD License. Table of Contents 1. Introduction ................................................. 3 2. High-level Architectures and their Consequences .............. 3 2.1. Service Provider Network Traversal ...................... 3 2.2. IPv4 Address Sharing .................................... 4 3. Detailed Analysis ............................................ 4 3.1. Architectural Differences ............................... 4 3.1.1. 464XLAT ............................................ 4 3.1.2. DS-Lite ............................................ 5 3.1.3. Lw4o6 .............................................. 5 3.1.4. MAP-E .............................................. 6 3.1.5. MAP-T .............................................. 6 3.1.6. Basic Comparison ................................... 6 3.2. Tradeoff between Port Number Efficiency and Stateless Operation ............................................. 7 3.3. Support for Server Operation ............................ 9 3.4. Support and Implementations ............................. 9 3.4.1. OS Support ......................................... 9 3.4.2. Support in Cellular and Broadband Networks ......... 9 3.4.3. Implementation Code Sizes ......................... 10 3.5. Typical Deployment and Traffic Volume Considerations ... 10 3.5.1. Deployment Possibilities .......................... 10 3.5.2. Cellular Networks with 464XLAT .................... 10 3.6. Load Sharing ........................................... 11 3.7. Logging ................................................ 11 4. Performance Comparison ...................................... 11 5. Security Considerations ..................................... 12 6. IANA Considerations ......................................... 12 7. Conclusions ................................................. 12 Lencse et al. Expires April 22, 2019 [Page 2] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 8. References .................................................. 13 8.1. Normative References ................................... 13 8.2. Informative References ................................. 14 9. Acknowledgments ............................................. 15 1. Introduction IETF has standardized a high number of IPv6 transition technologies [Len2017] and occupied a neutral position trusting the selection to the market. In the upcoming years, several network operators would like to get rid of the burden of maintaining IPv4 in their access and/or core networks. This document deals with five different solutions, each of which can be used to provide an IPv4 service using an IPv6-only access/core network. The following IPv6 transition technologies are covered: 464XLAT [RFC6877], DS-Lite (Dual Stack Lite) [RFC6333], lw4o6 (Lightweight 4over6) [RFC7596], MAP-E [RFC7597] and MAP-T [RFC7599]. 2. High-level Architectures and their Consequences 2.1. Service Provider Network Traversal As for the high-level solution of IPv6 service provider network traversal, MAP-T use double translation. First at the CE from IPv4 to IPv6 (NAT46), and then from IPv6 to IPv4 (NAT64), at the service provider network. 464XLAT may use double translation (stateless NAT46 + stateful NAT64) or single translation (stateful NAT64), depending on different factors, such as the use of DNS by the applications and the availability of a DNS64 function (in the host or in the service provider network). For deployment guidelines, please refer to [I- D.draft-ietf-v6ops-nat64-deployment]. DS-Lite, lw4o6 and MAP-E encapsulate the IPv4 packets into IPv6 packets. Each solution has its own advantages and drawbacks. Double translation results in only 20 bytes overhead (the difference in the minimum header size between IPv4 and IPv6), whereas the overhead of the encapsulation is 40 bytes (because both, the IPv4 and IPv6 headers are included). The difference may be significant in the case of small packet sizes or when the overhead results in fragmentation. Lencse et al. Expires April 22, 2019 [Page 3] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 The first step of the double translation cases is a stateless NAT from IPv4 to IPv6 implemented as SIIT (Stateless IP/ICMP Translation Algorithm) [RFC7915], which does not translate IPv4 options and/or multicast IP/ICMP packets, whereas with encapsulation-based technologies these remain intact. On the other hand, single and double translation results in "normal" IPv6 traffic which can be inspected, e.g., by hashing algorithms, and firewalls, whereas encapsulation results in IPv4-embedded IPv6 packets and their interpretation requires special software/hardware for looking further into the packet. The worst case is DS-Lite, which is also doing double stateful translation (NAT44 at the CE and NAT44 at the AFTR). Another consequence is that the solutions using double translation can carry only TCP, UDP or ICMP over IP, when they are used with IPv4 address sharing (please refer to section 3.3 for more details), whereas the solutions using encapsulation can carry any other protocols over IP, too. We also note that none of the five solutions support "native" IPv4 multicast. Please refer to Section 4 of [I-D.draft-ietf-v6ops- transition-ipv4aas] for the planned requirements for CE routers. 2.2. IPv4 Address Sharing All five technologies support IPv4 address sharing, which has severe consequences described in [RFC6269]. The efficiency of the address sharing of the five technologies is significantly different, it is discussed in section 3.2. We note that lw4o6, MAP-E and MAP-T can also be configured without IPv4 address sharing, see the details in Section 3.3. However in that case, there is no advantage in terms of public IPv4 address saving. 3. Detailed Analysis 3.1. Architectural Differences 3.1.1. 464XLAT When 464XLAT is used, in the simplest case, CLAT performs a stateless translation from IPv4 to IPv6 [RFC7915]. It uses IPv4- Lencse et al. Expires April 22, 2019 [Page 4] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 embedded IPv6 addresses [RFC6052] for both source address and destination address. PLAT performs stateful NAT64 [RFC6146]. Alternatively, when a dedicated /64 is not available for translation, the CLAT device uses a stateful NAT44 translation before the stateless NAT46 translation. Note that we generally do not see state close to the end-user as equally problematic as state in the middle of the network. In typical deployments, 464XLAT is used together with DNS64, see Section 3.1.2 of [I-D.draft-ietf-v6ops-nat64-deployment]. When an IPv6-only client communicates with an IPv4-only server, the DNS64 server returns the IPv4-embedded IPv6 address of the IPv4-only server. In this case, the IPv6-only client sends out IPv6 packets, thus CLAT functions as an IPv6 router and the PLAT performs a stateful NAT64 for these packets. Alternatively, one can say that the DNS64 + stateful NAT64 is used to carry the traffic of the IPv6-only client and the IPv4-only server, and the CLAT is used only for the IPv4 traffic from applications or devices that use literal IPv4 addresses or non-IPv6 compliant APIs. 3.1.2. DS-Lite The B4 (Basic Bridging BroadBand) element performs a stateful NAT44 and encapsulates the IPv4 packets into IPv6 packets. The AFTR (Address Family Transition Router) de-encapsulates the IPv4 packets from the IPv6 packets and performs stateful NAPT (Network Address and Port Translation). 3.1.3. Lw4o6 Lightweight 4over6 is a variant of DS-Lite. The difference is, that the stateful NAPT is moved from the AFTR to the lwB4 element, so a single stateful NAT44 is performed. It uses a provisioning mechanism to determine the size of the limited port-set per user. The AFTR becomes a lwAFTR. Alternatively, one can say that lw4o6 is a subset of MAP-E, as it uses the same provisioning, the same port mapping algorithm, and is indistinguishable from MAP-E when used without IPv4 address sharing. Lencse et al. Expires April 22, 2019 [Page 5] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 3.1.4. MAP-E The CE (Customer-Edge) router first performs a stateful NAPT44 [RFC2663] to transform the source addresses and source port numbers of the IPv4 packets into a predefined range, the size of which is a design parameter. The CE router then encapsulates the IPv4 packet in an IPv6 packet [RFC2473]. MAP defines a special stateless mapping algorithm, which encodes the relevant IPv4 address[es] into the IPv6 address, either wholly or partially depending on the BMR. Optionally, when used with IPv4 address sharing, port set bits may also be encoded in to the IPv6 source address. This transformation may be fine-tuned by the mapping rules. Packets destined outside of the MAP domain must traverse a MAP BR to be de-encapsulated. Packets destined for another CE router within the MAP domain may be forwarded directly with an appropriate FMR, and de-encapsulated by the destination CE router. 3.1.5. MAP-T MAP-T works very similarly to MAP-E, with the difference that it uses double translation instead of encapsulation. It can also be compared to 464XLAT when there is a double translation. After performing the above mentioned stateful NAPT44, the CE router performs stateless translation from IPv4 to IPv6 [RFC7915], which also translates the IPv4 address and port set ID into the IPv6 address space, based on the BMR. The MAP BR (Border Relay) performs stateless translation from IPv4 to IPv6 [RFC7915]. Using translation instead of encapsulation also allows IPv4-only nodes to correspond directly with IPv6 nodes in the MAP-T domain that have IPv4-embedded IPv6 addresses. 3.1.6. Basic Comparison The five IPv4aaS technologies can be classified into 2x2=4 categories on the basis of two aspects: . Technology used for service provider network traversal. It can be single/double translation or encapsulation. . Presence or absence of state in the operator network. Lencse et al. Expires April 22, 2019 [Page 6] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 State in the | Service provider network traversal technology operator | single/double | encapsulation/ network | translation | de-encapsulation ----------------+-----------------+----------------------- Present | 464XLAT | DS-Lite ----------------+-----------------+----------------------- Absent | MAP-T | MAP-E, lw4o6 3.2. Tradeoff between Port Number Efficiency and Stateless Operation 464XLAT and DS-Lite use stateful NAPT at the PLAT and AFTR devices, respectively. This may cause scalability issues. Lw4o6, MAP-E and MAP-T avoid using NAPT in the service provider network. Its cost is that they have to limit the port numbers available for a user. Although the number of ports available for a user is limited with all five technologies, when used with address sharing, the stateful technologies, such as 464XLAT and DS-Lite, allow for dynamic and centrally adjustable port allocations, whereas port ranges are predetermined and fixed with the three A+P (Address plus Port) based technologies, lw4o6, MAP-E, and MAP-T. Determining the optimal size of the fixed port set is not an easy task, but may also be impacted by local regulatory law, which may define a maximum number of users per IP address, and consequently a minimum number of ports per user. On the one hand, the "lack of ports" situation may cause serious problems in the operation of certain applications. For example, Miyakawa has demonstrated the consequences of the session number limitation due to port number shortage on the example of Google Maps [Miy2010]. When the limit was 15, several blocks of the map were missing, and the map was unusable. This study also provided several examples for the session numbers of different applications (the highest one was iTunes: 230-270 ports). The port number consumption of different applications is highly varying and e.g. in the case of web browsing it depends on several factors, including the choice of the web page, the web browser, and Lencse et al. Expires April 22, 2019 [Page 7] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 sometimes even the operating system [Rep2014]. For example, under certain conditions, 120-160 ports were used (URL: sohu.com, browser: Firefox under Ubuntu Linux), and in some other cases it was only 3- 12 ports (URL: twitter.com, browser: Iceweasel under Debian Linux). There may be several users behind a CE router, especially in the broadband case (e.g. Internet is used by different members of a family simultaneously), so sufficient ports must be allocated to avoid impacting user experience. However, on the other hand, assigning too many ports per CE router will result in waste of public IPv4 addresses, which is a scarce and expensive resource. We note that common CE router NAT44 implementations utilizing Netfilter, use a 3-tuple (source address, destination address, and destination port) approach for source port allocation; external source ports will be reused for unique internal source and destination address and port flows. It is also noted, that Netfilter cannot currently make use of multiple source port ranges, this may influence the design when using stateless technologies. Stateful technologies, 464XLAT and DS-Lite (and also NAT444) can therefore be much more efficient in terms of port allocation and thus public IP address saving. The price is the stateful operation in the service provider network, which is allegedly does not scale up well. It should be noticed that in many cases, all those factors may depend on how it is actually implemented. XXX MEASUREMENTS ARE PLANNED TO DECIDE IF IT IS TRUE. XXX We note that these CGN-type solutions can allocate ports dynamically "on the fly". Depending on configuration, this can result in the same customer being allocated ports from different source addresses. This can cause operational issues for protocols and applications that expect multiple flows to be sourced from the same address. E.g., ECMP hashing, STUN, gaming, content delivery networks. However, it should be noticed that this is the same problem when a network has a NAT44 with multiple public IPv4 addresses, or even when applications in a dual-stack case, behave wrongly if happy eyeballs is flapping the flow address between IPv4 and IPv6. The consequences of IPv4 address sharing [RFC6269] may impact all five technologies. However, when ports are allocated dynamically, more customers may get ports from the same public IPv4 address, which may results in negative consequences with higher probability, e.g. many applications and service providers (Sony PlayStation Lencse et al. Expires April 22, 2019 [Page 8] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 Network, OpenDNS, etc.) permanently black-list IPv4 ranges if they detect that they are used for address sharing. Both cases are, again, implementation dependent. We note that although it is not of typical use, one can do deterministic stateful NAT and reserve a fixed set of ports for each customer, too. 3.3. Support for Server Operation Lw4o6, MAP-E and MAP-T may be configured without IPv4 address sharing, allowing exclusive use of all ports, and non-port-based layer 4 protocols. Thus, they may also be used to support server/services operation. However, when public IPv4 addresses are assigned to the CE router without address sharing, obviously there is no advantage in terms of IPv4 public addresses saving. It is also possible to configure specific ports mapping in 464XLAT/NAT64 using EAMT [RFC7757], which means that only those ports are "lost" from the pool of addresses, so there is a higher maximization of the total usage of IPv4/port resources. We note that MAP-E and MAP-T may also provide more than one IP address (that is a complete prefix) to the customers. 3.4. Support and Implementations 3.4.1. OS Support As for 464XLAT, client support (CLAT) exists in Windows 10, Linux (including Android), Windows Mobile, Chrome OS and iOS, but it is missing from MacOS. For the other four solutions, we are not aware of any OS support. 3.4.2. Support in Cellular and Broadband Networks Several cellular networks use 464XLAT, whereas we are not aware of any deployment of the four other technologies in cellular networks, as they are not supported. In broadband networks, there are some deployments of 464XLAT, MAP-E and MAP-T. Both, lw4o6 and DS-Lite have more deployments, having been up now DS-Lite the most used one, but lw4o6 taking over in the last years. Lencse et al. Expires April 22, 2019 [Page 9] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 3.4.3. Implementation Code Sizes As for complexity hint, the code size reported from OpenWRT implementation is 17kB, 35kB, 15kB, 35kB, and 48kB for 464XLAT, lw4o6, DS-Lite, MAP-E, MAP-T, and lw4o6, respectively (https://openwrt.org/packages/start). We note that the support for all five technologies requires much less code size than the total sum of the above quantities, because they contain a lot of common functions (data plane is shared among several of them). 3.5. Typical Deployment and Traffic Volume Considerations 3.5.1. Deployment Possibilities Theoretically, all five covered IPv4aaS technologies could be used together with DNS64 + stateful NAT64, as it is done in 464XLAT. In this case the CE router would treat the traffic between an IPv6-only client and IPv4-only server as normal IPv6 traffic, and the stateful NAT64 gateway would do a single translation, thus offloading this kind of traffic from the IPv4aaS technology. The cost of this solution would be the need for deploying also DNS64 + stateful NAT64. However, this has not been implemented in clients or actual deployments, so only 464XLAT always uses this optimization and the other four solutions do not use it at all. 3.5.2. Cellular Networks with 464XLAT Actual figures from existing deployments, show that the typical traffic volumes in an IPv6-only cellular network, when 464XLAT technology is used together with DNS64, are: . 75% of traffic is IPv6 end-to-end (no translation) . 24% of traffic is uses DNS64 + NAT64 (1 translation) . Less than 1% of traffic use the CLAT in addition to NAT64 (2 translations), due to an IPv4 socket and/or IPv4 literal. Without using DNS64, 25% of the traffic would undergo double translation. Lencse et al. Expires April 22, 2019 [Page 10] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 3.6. Load Sharing If multiple network-side devices are needed as PLAT/AFTR/BR for capacity, then there is a need for a load sharing technology. ECMP (Equal-Cost Multi-Path) load sharing can be used for all technologies, however stateful technologies will be impacted by changes in network topology or device failure. Technologies utilizing DNS64 can also distribute load across PLAT/AFTR devices, evenly or unevenly, by using different prefixes. Different network specific prefixes can be distributed for subscribers in appropriately sized segments (like split-horizon DNS, also called DNS views). Stateless technologies, due to the lack of flow tracking, can make use of anycast routing for load sharing and resiliency across network-devices, both ingress and egress; flows can take asymmetric paths through the network, i.e., in through one lwAFTR/BR and out via another. 3.7. Logging In the case of 464XLAT and DS-Lite, it varies with time who uses a given public IPv4 address and port combination, therefore, logging is necessary to be able to investigate possible abuses. Configurations that dynamically assign ports "on the fly", will have a much higher capacity requirement for logging, than those that assign port blocks or ranges. Stateless technologies that algorithmically assign addresses and ports, e.g., lw4o6, MAP-T, MAP-E, may require additional support tools to assist in resolving assignments, but require no additional logging. 4. Performance Comparison We plan to compare the performances of the most prominent free software implementations of the five IPv6 transition technologies using the methodology described in "Benchmarking Methodology for IPv6 Transition Technologies" [RFC8219]. On the one hand, the Dual DUT Setup of RFC8219 makes it possible to use the existing "Benchmarking Methodology for Network Interconnect Devices" [RFC2544] compliant measurement devices, however, this setup has the drawback that the performances of the CE and of the ISP side device (e.g. the CLAT and the PLAT of 464XLAT) are measured Lencse et al. Expires April 22, 2019 [Page 11] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 together. In order to measure the performance of only one of them, we need to ensure that the desired one is the bottleneck. On the other hand, the Single DUT Setup of [RFC8219] makes it possible to benchmark the selected device separately, however, no [RFC8219] compliant testers available yet. A DPDK-based software Tester for stateless NAT64 is currently under development and it is expected to be available this autumn as a free software. XXX FROM WHERE XXX Any volunteers for developing [RFC8219] compliant measurement software? 5. Security Considerations According to the simplest model, the number of bugs is proportional to the number of code lines. Please refer to section 3.4.3 for code sizes of CE implementations. For all five technologies, the CE device should contain a DNS proxy. However, the user may change DNS settings. If it happens and lw4o6, MAP-E and MAP-T are used with significantly restricted port set, which is required for an efficient public IPv4 address sharing, the entropy of the source ports is significantly lowered (e.g. from 16 bits to 10 bits, when 1024 port numbers are assigned to each subscriber) and thus these technologies are theoretically less resilient against cache poisoning, see [RFC5452]. However, an efficient cache poisoning attack requires that the subscriber operates an own caching DNS server and the attack is performed in the service provider network. Thus, we consider the chance of the successful exploitation of this vulnerability as low. An in-depth security analysis of all five IPv6 transition technologies and their most prominent free software implementations according to the methodology defined in [Len2018] is planned. 6. IANA Considerations TBD. 7. Conclusions TBD. Lencse et al. Expires April 22, 2019 [Page 12] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 8. References 8.1. Normative References [RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for Network Interconnect Devices", RFC 2544, DOI 10.17487/RFC2544, March 1999, . [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, December 1998, . [RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address Translator (NAT) Terminology and Considerations", RFC 2663, DOI 10.17487/RFC2663, August 1999, . [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, DOI 10.17487/RFC6052, October 2010, . [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, April 2011, . [RFC6877] Mawatari, M., Kawashima, M., and C. Byrne, "464XLAT: Combination of Stateful and Stateless Translation", RFC 6877, DOI 10.17487/RFC6877, April 2013, . Lencse et al. Expires April 22, 2019 [Page 13] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 [RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I. Farrer, "Lightweight 4over6: An Extension to the Dual- Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596, July 2015, . [RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S., Murakami, T., and T. Taylor, Ed., "Mapping of Address and Port with Encapsulation (MAP-E)", RFC 7597, DOI 10.17487/RFC7597, July 2015, . [RFC7599] Li, X., Bao, C., Dec, W., Ed., Troan, O., Matsushima, S., and T. Murakami, "Mapping of Address and Port using Translation (MAP-T)", RFC 7599, DOI 10.17487/RFC7599, July 2015, . [RFC7915] Bao, C., Li, X., Baker, F., Anderson, T., and F. Gont, "IP/ICMP translation algorithm", RFC 7915, DOI: 10.17487/RFC7915, June 2016, . [RFC7757] Anderson, T., and A. Leiva Popper "Explicit Address Mappings for Stateless IP/ICMP Translation", RFC 7757, DOI 10.17487/RFC7757, February 2016, . [RFC8219] Georgescu, M., Pislaru, L., and G. Lencse, "Benchmarking Methodology for IPv6 Transition Technologies", IETF RFC 8219, DOI: 10.17487/RFC8219, Aug. 2017, . 8.2. Informative References [I-D.draft-ietf-v6ops-nat64-deployment] J. Palet, "NAT64/464XLAT Deployment Guidelines in Operator and Enterprise Networks", draft-ietf-v6ops-nat64-deployment-03, (work in progress), October 2018. [I-D.draft-ietf-v6ops-transition-ipv4aas] Palet, J., Liu, H., and M. Kawashima, "Requirements for IPv6 Customer Edge Routers to Support IPv4 Connectivity as-a-Service", draft-ietf-v6ops- transition-ipv4aas-10, (work in progress), October 2018. Lencse et al. Expires April 22, 2019 [Page 14] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 [Len2017] Lencse, G., and Y. Kadobayashi, "Survey of IPv6 Transition Technologies for Security Analysis", IEICE Communications Society Internet Architecture Workshop, Tokyo, Japan, Aug. 28, 2017, IEICE Tech. Rep., vol. 117, no. 187, pp. 19-24. http://www.hit.bme.hu/~lencse/publications/IEICE-IA-2017- survey.pdf [Len2018] Lencse, G., and Y. Kadobayashi, "Methodology for the identification of potential security issues of different IPv6 transition technologies: Threat analysis of DNS64 and stateful NAT64", Computers & Security (Elsevier), vol. 77, no. 1, pp. 397-411, August 1, 2018, DOI: 10.1016/j.cose.2018.04.012, http://www.hit.bme.hu/~lencse/publications/ECS-2018- Methodology-revised.pdf [Miy2010] Miyakawa, S., "IPv4 to IPv6 transformation schemes", IEICE Trans. Commun., vol.E93-B, no.5, pp.1078-1084, May 2010. DOI:10.1587/transcom.E93.B.1078 [Rep2014] Repas, S., Hajas, T., and G. Lencse, "Port number consumption of the NAT64 IPv6 transition technology", Proc. 37th Internat. Conf. on Telecommunications and Signal Processing (TSP 2014), Berlin, Germany, pp.66-72, Jul. 1-3, 2014. DOI: 10.1109/TSP.2015.7296411 9. Acknowledgments The authors would like to thank Ole Troan for his thorough review of this draft and acknowledge the inputs of Ole Troan, Mark Andrews, Edwin Cordeiro, Fred Baker, Alexandre Petrescu, Cameron Byrne, Tore Anderson, Alexandre Petrescu, Mikael Abrahamsson, Gert Doering, Satoru Matsushima, and TBD. This document was prepared using 2-Word-v2.0.template.dot. Copyright (c) 2018 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). Lencse et al. Expires April 22, 2019 [Page 15] Internet-Draft Pros and Cons of IPv4aaS Technologies October 2018 Authors' Addresses Gabor Lencse Budapest University of Technology and Economics Magyar Tudosok korutja 2. H-1117 Budapest, Hungary Email: lencse@hit.bme.hu Jordi Palet Martinez The IPv6 Company Molino de la Navata, 75 La Navata - Galapagar, Madrid - 28420 Spain Email: jordi.palet@theipv6company.com Lee Howard Retevia 9940 Main St., Suite 200 Fairfax Virginia 22031, USA Email: lee@asgard.org Richard Patterson Sky UK 1 Brick Lane London, E1 6PU United Kingdom Email: richard.patterson@sky.uk Lencse et al. Expires April 22, 2019 [Page 16]