--- 1/draft-ietf-v6ops-nat64-deployment-06.txt 2019-07-08 06:14:24.922611985 -0700 +++ 2/draft-ietf-v6ops-nat64-deployment-07.txt 2019-07-08 06:14:25.014614304 -0700 @@ -1,19 +1,19 @@ v6ops J. Palet Martinez Internet-Draft The IPv6 Company -Intended status: Informational May 4, 2019 -Expires: November 5, 2019 +Intended status: Informational July 8, 2019 +Expires: January 9, 2020 Additional NAT64/464XLAT Deployment Guidelines in Operator and Enterprise Networks - draft-ietf-v6ops-nat64-deployment-06 + draft-ietf-v6ops-nat64-deployment-07 Abstract This document describes how NAT64 (including 464XLAT) can be deployed in an IPv6 network, whether cellular ISP, broadband ISP, or enterprise, and possible optimizations. The document also discusses issues to be considered when having IPv6-only connectivity, regarding: a) DNS64, b) applications or devices that use literal IPv4 addresses or non-IPv6 compliant APIs, and c) IPv4-only hosts or applications. @@ -26,21 +26,21 @@ 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 https://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 November 5, 2019. + This Internet-Draft will expire on January 9, 2020. Copyright Notice Copyright (c) 2019 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 (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -51,64 +51,65 @@ described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . 5 3. NAT64 Deployment Scenarios . . . . . . . . . . . . . . . . . 5 3.1. Known to Work . . . . . . . . . . . . . . . . . . . . . . 6 3.1.1. Service Provider NAT64 with DNS64 . . . . . . . . . . 6 3.1.2. Service Provider Offering 464XLAT, with DNS64 . . . . 8 - 3.1.3. Service Provider Offering 464XLAT, without DNS64 . . 11 + 3.1.3. Service Provider Offering 464XLAT, without DNS64 . . 12 3.2. Known to Work Under Special Conditions . . . . . . . . . 14 3.2.1. Service Provider NAT64 without DNS64 . . . . . . . . 14 - 3.2.2. Service Provider NAT64; DNS64 in the IPv6 hosts . . . 15 + 3.2.2. Service Provider NAT64; DNS64 in the IPv6 hosts . . . 16 3.2.3. Service Provider NAT64; DNS64 in the IPv4-only remote network . . . . . . . . . . . . . . . . . . . 16 - 3.3. Comparing the Scenarios . . . . . . . . . . . . . . . . . 16 - 4. Issues to be Considered . . . . . . . . . . . . . . . . . . . 18 - 4.1. DNSSEC Considerations and Possible Approaches . . . . . . 18 + 3.3. Comparing the Scenarios . . . . . . . . . . . . . . . . . 17 + 4. Issues to be Considered . . . . . . . . . . . . . . . . . . . 19 + 4.1. DNSSEC Considerations and Possible Approaches . . . . . . 19 4.1.1. Not using DNS64 . . . . . . . . . . . . . . . . . . . 20 4.1.2. DNSSEC validator aware of DNS64 . . . . . . . . . . . 21 - 4.1.3. Stub validator . . . . . . . . . . . . . . . . . . . 21 - 4.1.4. CLAT with DNS proxy and validator . . . . . . . . . . 21 + 4.1.3. Stub validator . . . . . . . . . . . . . . . . . . . 22 + 4.1.4. CLAT with DNS proxy and validator . . . . . . . . . . 22 4.1.5. ACL of clients . . . . . . . . . . . . . . . . . . . 22 - 4.1.6. Mapping-out IPv4 addresses . . . . . . . . . . . . . 22 - 4.2. DNS64 and Reverse Mapping . . . . . . . . . . . . . . . . 22 - 4.3. Using 464XLAT with/without DNS64 . . . . . . . . . . . . 22 - 4.4. Foreign DNS . . . . . . . . . . . . . . . . . . . . . . . 23 - 4.4.1. Manual Configuration of Foreign DNS . . . . . . . . . 24 - 4.4.2. DNS Privacy . . . . . . . . . . . . . . . . . . . . . 24 - 4.4.3. Split DNS . . . . . . . . . . . . . . . . . . . . . . 25 - 4.5. Well-Known Prefix (WKP) vs Network-Specific Prefix (NSP) 25 - 4.6. IPv4 literals and old APIs . . . . . . . . . . . . . . . 25 - 4.7. IPv4-only Hosts or Applications . . . . . . . . . . . . . 26 - 4.8. CLAT Translation Considerations . . . . . . . . . . . . . 26 - 4.9. EAM Considerations . . . . . . . . . . . . . . . . . . . 27 - 4.10. Incoming Connections . . . . . . . . . . . . . . . . . . 27 - 5. Summary of Deployment Recommendations for NAT64/464XLAT . . . 27 - 6. Deployment of NAT64 in Enterprise Networks . . . . . . . . . 30 - 7. Security Considerations . . . . . . . . . . . . . . . . . . . 32 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 - 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32 - 10. ANNEX A: Example of Broadband Deployment with 464XLAT . . . . 32 - 11. ANNEX B: CLAT Implementation . . . . . . . . . . . . . . . . 36 - 12. ANNEX C: Benchmarking . . . . . . . . . . . . . . . . . . . . 37 - 13. ANNEX D: Changes from -00 to -01/-02 . . . . . . . . . . . . 37 - 14. ANNEX E: Changes from -02 to -03 . . . . . . . . . . . . . . 37 - 15. ANNEX F: Changes from -03 to -04 . . . . . . . . . . . . . . 38 - 16. ANNEX G: Changes from -04 to -05 . . . . . . . . . . . . . . 38 - 17. ANNEX H: Changes from -05 to -06 . . . . . . . . . . . . . . 38 - 18. References . . . . . . . . . . . . . . . . . . . . . . . . . 38 - 18.1. Normative References . . . . . . . . . . . . . . . . . . 38 - 18.2. Informative References . . . . . . . . . . . . . . . . . 41 - Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 43 + 4.1.6. Mapping-out IPv4 addresses . . . . . . . . . . . . . 23 + 4.2. DNS64 and Reverse Mapping . . . . . . . . . . . . . . . . 23 + 4.3. Using 464XLAT with/without DNS64 . . . . . . . . . . . . 23 + 4.4. Foreign DNS . . . . . . . . . . . . . . . . . . . . . . . 24 + 4.4.1. Manual Configuration of DNS . . . . . . . . . . . . . 25 + 4.4.2. DNS Privacy/Encryption Mechanisms . . . . . . . . . . 25 + 4.4.3. Split DNS . . . . . . . . . . . . . . . . . . . . . . 26 + 4.5. Well-Known Prefix (WKP) vs Network-Specific Prefix (NSP) 26 + 4.6. IPv4 literals and non-IPv6 Compliant APIs . . . . . . . . 26 + 4.7. IPv4-only Hosts or Applications . . . . . . . . . . . . . 27 + 4.8. CLAT Translation Considerations . . . . . . . . . . . . . 27 + 4.9. EAM Considerations . . . . . . . . . . . . . . . . . . . 28 + 4.10. Incoming Connections . . . . . . . . . . . . . . . . . . 28 + 5. Summary of Deployment Recommendations for NAT64/464XLAT . . . 28 + 6. Deployment of NAT64 in Enterprise Networks . . . . . . . . . 31 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 33 + 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 + 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 33 + 10. ANNEX A: Example of Broadband Deployment with 464XLAT . . . . 34 + 11. ANNEX B: CLAT Implementation . . . . . . . . . . . . . . . . 37 + 12. ANNEX C: Benchmarking . . . . . . . . . . . . . . . . . . . . 38 + 13. ANNEX D: Changes from -00 to -01/-02 . . . . . . . . . . . . 38 + 14. ANNEX E: Changes from -02 to -03 . . . . . . . . . . . . . . 38 + 15. ANNEX F: Changes from -03 to -04 . . . . . . . . . . . . . . 39 + 16. ANNEX G: Changes from -04 to -05 . . . . . . . . . . . . . . 39 + 17. ANNEX H: Changes from -05 to -06 . . . . . . . . . . . . . . 39 + 18. ANNEX H: Changes from -06 to -07 . . . . . . . . . . . . . . 39 + 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 39 + 19.1. Normative References . . . . . . . . . . . . . . . . . . 39 + 19.2. Informative References . . . . . . . . . . . . . . . . . 42 + Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 45 1. Introduction Stateful NAT64 ([RFC6146]) describes a stateful IPv6 to IPv4 translation mechanism, which allows IPv6-only hosts to communicate with IPv4-only servers using unicast UDP, TCP, or ICMP, by means of IPv4 public addresses sharing, among multiple IPv6-only hosts. Unless otherwise stated, references in the rest of this document to NAT64 (function) should be interpreted as to Stateful NAT64. @@ -149,20 +150,27 @@ by means of IPv6-only connectivity. This is just an example which may apply to many other similar cases. All them are deployment specific. According to that, across this document, the use of "operator", "operator network", "service provider", and similar ones, are interchangeable with equivalent cases of enterprise networks (and similar ones). This may be also the case for "managed end-user networks". + Note that if all the hosts in a network were performing the address + synthesis, as described in Section 7.2 of [RFC6147], some of the + drawbacks may vanish. However, it is today unrealistic to expect + that, considering the high number of devices and applications that + aren't yet IPv6-enabled. So, in this document, this will be + considered only for specific scenarios that can guarantee it. + An analysis of stateful IPv4/IPv6 mechanisms is provided in [RFC6889]. This document looks into different possible NAT64 ([RFC6146]) deployment scenarios, including IPv4-IPv6-IPv4 (464 for short) and similar ones, which were not documented in [RFC6144], such as 464XLAT ([RFC6877]), in operator (broadband and cellular) and enterprise networks, and provides guidelines to avoid operational issues. Towards that, this document first looks into the possible NAT64 @@ -172,21 +180,21 @@ operator need to understand on different matters that will allow to define what is the best approach/scenario for each specific network case. A summary provides some recommendations and decision points. A section with clarifications on the usage of this document for enterprise networks, is also provided. Finally, an annex provides an example of a broadband deployment using 464XLAT and another annex provides hints for a CLAT implementation. [RFC7269] already provides information about NAT64 deployment options and experiences. Both, this document and [RFC7269] are - complementary, as they are looking into different deployment + complementary; they are looking into different deployment considerations and furthermore, this document is considering the updated deployment experience and newer standards. The target deployment scenarios in this document may be covered as well by other IPv4-as-a-Service (IPv4aaS) transition mechanisms. Note that this is true only for the case of broadband networks, as in the case of cellular networks the only supported solution is the use of NAT64/464XLAT. So, it is out of scope of this document to provide a comparison among the different IPv4aaS transition mechanisms, which is being analyzed already in [I-D.lmhp-v6ops-transition-comparison]. @@ -239,103 +247,109 @@ 3. A NAT64 function (NAT64) in the service provider. 4. A DNS64 function (DNS64) in the service provider. 5. An external service provider offering the NAT64 function and/or the DNS64 function (extNAT64/extDNS64). 6. 464XLAT customer side translator (CLAT). Note that the nomenclature used in parenthesis is the one that, for - short, will be used in the figures. + short, will be used in the figures. Note also that for simplicity, + the boxes in the figures don't mean they are actually a single + device; they just represent one or more functions as located in that + part of the network (i.e. a single box with NAT64 and DNS64 functions + can actually be several devices, not just one). The possible scenarios are split in two general categories: 1. Known to work. 2. Known to work under special conditions. 3.1. Known to Work - The scenarios in this category are known to work. Each one may have - different pros and cons, and in some cases the trade-offs, maybe - acceptable for some operators. + The scenarios in this category are known to work, as there are well- + known existing deployments from different operators using them. Each + one may have different pros and cons, and in some cases the trade- + offs, maybe acceptable for some operators. 3.1.1. Service Provider NAT64 with DNS64 - In this scenario, the service provider offers both, the NAT64 and the - DNS64 functions. + In this scenario (Figure 1), the service provider offers both, the + NAT64 and the DNS64 functions. This is the most common scenario as originally considered by the designers of NAT64 ([RFC6146]) and DNS64 ([RFC6147]), however also may have the implications related the DNSSEC. This scenario also may fail to solve the issue of IPv4 literal addresses or non-IPv6 compliant APIs, as well as the issue of IPv4-only hosts or applications behind the IPv6-only access network. +----------+ +----------+ +----------+ | | | NAT64 | | | | IPv6 +--------+ + +--------+ IPv4 | | | | DNS64 | | | +----------+ +----------+ +----------+ Figure 1: NAT64 with DNS64 - A similar scenario will be if the service provider offers only the - DNS64 function, and the NAT64 function is provided by an outsourcing - agreement with an external provider. All the considerations in the - previous paragraphs of this section are the same for this sub-case. + A similar scenario (Figure 2) will be if the service provider offers + only the DNS64 function, and the NAT64 function is provided by an + outsourcing agreement with an external provider. All the + considerations in the previous paragraphs of this section, are the + same for this sub-case. +----------+ +----------+ | | | | | extNAT64 +--------+ IPv4 | | | | | +----+-----+ +----------+ | | +----------+ +----+-----+ | | | | | IPv6 +--------+ DNS64 + | | | | +----------+ +----------+ Figure 2: NAT64 in external service provider - This is equivalent to the scenario where the outsourcing agreement - with the external provider is to provide both the NAT64 and DNS64 - functions. Once more, all the considerations in the previous + This is equivalent to the scenario (Figure 3) where the outsourcing + agreement with the external provider is to provide both the NAT64 and + DNS64 functions. Once more, all the considerations in the previous paragraphs of this section are the same for this sub-case. +----------+ +----------+ | extNAT64 | | | | + +-------+ IPv4 | | extDNS64 | | | +----+-----+ +----------+ | +----------+ | | | | | IPv6 +-------------+ | | +----------+ Figure 3: NAT64 and DNS64 in external provider - One more equivalent scenario will be if the service provider offers - the NAT64 function only, and the DNS64 function is from an external - provider with or without a specific agreement among them. This is a - scenario already common today, as several "global" service providers - provide free DNS/DNS64 services and users often configure manually - their DNS. This will only work if both the NAT64 and the DNS64 - functions are using the WKP (Well-Known Prefix) or the same NSP - (Network-Specific Prefix). All the considerations in the previous - paragraphs of this section are the same for this sub-case. + One additional equivalent scenario (Figure 4) will be if the service + provider offers the NAT64 function only, and the DNS64 function is + from an external provider with or without a specific agreement among + them. This is a scenario already common today, as several "global" + service providers provide free DNS/DNS64 services and users often + configure manually their DNS. This will only work if both the NAT64 + and the DNS64 functions are using the WKP (Well-Known Prefix) or the + same NSP (Network-Specific Prefix). All the considerations in the + previous paragraphs of this section, are the same for this sub-case. Of course, if the external DNS64 function is agreed with the service provider, then we are in the same case as in the previous ones already depicted in this scenario. +----------+ | | | extDNS64 | | | +----+-----+ @@ -371,22 +385,22 @@ 3. Optionally, DNS64 ([RFC6147]), may allow an optimization: a single translation at the NAT64, instead of two translations (NAT46+NAT64), when the application at the end-user device supports IPv6 DNS (uses AAAA Resource Records). Note that even if in the 464XLAT ([RFC6877]) terminology, the provider-side translator is referred as PLAT, for simplicity and uniformity, across this document is always referred as NAT64 (function). - In this scenario the service provider deploys 464XLAT with a DNS64 - function. + In this scenario (Figure 5) the service provider deploys 464XLAT with + a DNS64 function. As a consequence, the DNSSEC issues remain, unless the host is doing the address synthesis. 464XLAT ([RFC6877]) is a very simple approach to cope with the major NAT64+DNS64 drawback: Not working with applications or devices that use literal IPv4 addresses or non-IPv6 compliant APIs. 464XLAT ([RFC6877]) has been used initially mainly in IPv6-only cellular networks. By supporting a CLAT function, the end-user @@ -397,21 +411,22 @@ In addition to that, in the same example of the cellular network above, if the User Equipment (UE) provides tethering, other devices behind it will be presented with a traditional NAT44, in addition to the native IPv6 support, so clearly it allows IPv4-only hosts behind the IPv6-only access network. Furthermore, as discussed in [RFC6877], 464XLAT can be used in broadband IPv6 network architectures, by implementing the CLAT function at the CE. - The support of this scenario offers two additional advantages: + The support of this scenario in a network, offers two additional + advantages: o DNS load optimization: A CLAT should implement a DNS proxy (as per [RFC5625]), so that only IPv6 native queries and only for AAAA records are sent to the DNS64 server. Otherwise doubling the number of queries may impact the DNS infrastructure. o Connection establishment delay optimization: If the UE/CE implementation is detecting the presence of a DNS64 function, it may issue only the AAAA query, instead of both the AAAA and A queries. @@ -460,89 +475,93 @@ placing the different elements. +----------+ +----------+ +----------+ | IPv6 | | NAT64 | | | | + +--------+ + +--------+ IPv4 | | CLAT | | DNS64 | | | +----------+ +----------+ +----------+ Figure 5: 464XLAT with DNS64 - A similar scenario will be if the service provider offers only the - DNS64 function, and the NAT64 function is provided by an outsourcing - agreement with an external provider. All the considerations in the - previous paragraphs of this section are the same for this sub-case. + A similar scenario (Figure 6) will be if the service provider offers + only the DNS64 function, and the NAT64 function is provided by an + outsourcing agreement with an external provider. All the + considerations in the previous paragraphs of this section are the + same for this sub-case. +----------+ +----------+ | | | | | extNAT64 +--------+ IPv4 | | | | | +----+-----+ +----------+ | | +----------+ +----+-----+ | IPv6 | | | | + +--------+ DNS64 + | CLAT | | | +----------+ +----------+ Figure 6: 464XLAT with DNS64; NAT64 in external provider - As well, is equivalent to the scenario where the outsourcing - agreement with the external provider is to provide both the NAT64 and - DNS64 functions. Once more, all the considerations in the previous - paragraphs of this section are the same for this sub-case. + As well, is equivalent to the scenario (Figure 7) where the + outsourcing agreement with the external provider is to provide both + the NAT64 and DNS64 functions. Once more, all the considerations in + the previous paragraphs of this section are the same for this sub- + case. +----------+ +----------+ | extNAT64 | | | | + +--------+ IPv4 | | extDNS64 | | | +----+-----+ +----------+ | +----------+ | | IPv6 | | | + +-------------+ | CLAT | +----------+ Figure 7: 464XLAT with DNS64; NAT64 and DNS64 in external provider 3.1.3. Service Provider Offering 464XLAT, without DNS64 - The major advantage of this scenario, using 464XLAT without DNS64, is - that the service provider ensures that DNSSEC is never broken, even - in case the user modifies the DNS configuration. Nevertheless, some - CLAT implementations or applications may impose an extra delay, which - is induced by the dual A/AAAA queries (and wait for both responses), - unless Happy Eyeballs v2 (HEv2, [RFC8305]) is also present. + The major advantage of this scenario (Figure 8), using 464XLAT + without DNS64, is that the service provider ensures that DNSSEC is + never broken, even in case the user modifies the DNS configuration. + Nevertheless, some CLAT implementations or applications may impose an + extra delay, which is induced by the dual A/AAAA queries (and wait + for both responses), unless Happy Eyeballs v2 ([RFC8305]) is also + present. A possible variation of this scenario is the case when DNS64 is used only for the discovery of the NAT64 prefix. The rest of the document is not considering it as a different scenario, because once the prefix has been discovered, the DNS64 function is not used, so it behaves as if the DNS64 synthesis function is not present. In this scenario, as in the previous one, there are no issues related to IPv4-only hosts (or IPv4-only applications) behind the IPv6-only access network, neither related to the usage of IPv4 literals or non- IPv6 compliant APIs. - The support of this scenario offers one advantage: + The support of this scenario in a network, offers one advantage: o DNS load optimization: A CLAT should implement a DNS proxy (as per [RFC5625]), so that only IPv6 native queries are sent to the DNS64 server. Otherwise doubling the number of queries may impact the DNS infrastructure. As indicated earlier, the connection establishment delay optimization is achieved only in the case of devices, Operating Systems, or - applications that use HEv2 ([RFC8305]), which is very common. + applications that use Happy Eyeballs v2 ([RFC8305]), which is very + common. Let's assume the representation of two dual-stack peers as in the previous case: +-------+ .-----. .-----. | | / \ / \ .-----. | Res./ | / IPv6- \ .-----. / IPv4- \ / Local \ | SOHO +--( only )---( NAT64 )---( only ) / \ | | \ flow /\ `-----' \ flow / ( Dual- )--+ IPv6 | \ / \ / \ / @@ -595,24 +614,24 @@ different elements. +----------+ +----------+ +----------+ | IPv6 | | | | | | + +--------+ NAT64 +--------+ IPv4 | | CLAT | | | | | +----------+ +----------+ +----------+ Figure 8: 464XLAT without DNS64 - This is equivalent to the scenario where there is an outsourcing - agreement with an external provider for the NAT64 function. All the - considerations in the previous paragraphs of this section are the - same for this sub-case. + This is equivalent to the scenario (Figure 9) where there is an + outsourcing agreement with an external provider for the NAT64 + function. All the considerations in the previous paragraphs of this + section are the same for this sub-case. +----------+ +----------+ | | | | | extNAT64 +--------+ IPv4 | | | | | +----+-----+ +----------+ | +----------+ | | IPv6 | | | + +-------------+ @@ -626,22 +645,22 @@ The scenarios in this category are known to not work unless significant effort is devoted to solve the issues, or are intended to solve problems across "closed" networks, instead of as a general Internet access usage. In addition to the different pros, cons and trade-offs, which may be acceptable for some operators, they have implementation difficulties, as they are beyond the original expectations of the NAT64/DNS64 original intent. 3.2.1. Service Provider NAT64 without DNS64 - In this scenario, the service provider offers a NAT64 function, - however there is no DNS64 function support at all. + In this scenario (Figure 10), the service provider offers a NAT64 + function, however there is no DNS64 function support at all. As a consequence, an IPv6 host in the IPv6-only access network, will not be able to detect the presence of DNS64 by means of [RFC7050], neither to learn the IPv6 prefix to be used for the NAT64 function. This can be sorted out as indicated in Section 4.1.1. However, despite that, because the lack of the DNS64 function, the IPv6 host will not be able to obtain AAAA synthesized records, so the NAT64 function becomes useless. @@ -676,50 +695,51 @@ +----------+ +----------+ +----------+ | | | | | | | IPv6 +--------+ NAT64 +--------+ IPv4 | | | | | | | +----------+ +----------+ +----------+ Figure 10: NAT64 without DNS64 3.2.2. Service Provider NAT64; DNS64 in the IPv6 hosts - In this scenario, the service provider offers the NAT64 function, but - not the DNS64 function. However, the IPv6 hosts have a built-in - DNS64 function. + In this scenario (Figure 11), the service provider offers the NAT64 + function, but not the DNS64 function. However, the IPv6 hosts have a + built-in DNS64 function. This may become common if the DNS64 function is implemented in all - the IPv6 hosts/stacks, which is not the actual situation, but it may - happen in the medium-term. At this way, the DNSSEC validation is - performed on the A record, and then the host can use the DNS64 - function so to be able to use the NAT64 function, without any DNSSEC - issues. + the IPv6 hosts/stacks. However, commonly this is not the actual + situation, even if it may happen in the medium-term. At this way, + the DNSSEC validation is performed on the A record, and then the host + can use the DNS64 function so to be able to use the NAT64 function, + without any DNSSEC issues. This scenario fails to solve the issue of IPv4 literal addresses or - non-IPv6 compliant APIs, unless the IPv6 hosts also supports HEv2 - ([RFC8305], Section 7.1), which may solve that issue. + non-IPv6 compliant APIs, unless the IPv6 hosts also supports Happy + Eyeballs v2 ([RFC8305], Section 7.1), which may solve that issue. However, this scenario still fails to solve the problem of IPv4-only hosts or applications behind the IPv6-only access network. +----------+ +----------+ +----------+ | IPv6 | | | | | | + +--------+ NAT64 +--------+ IPv4 | | DNS64 | | | | | +----------+ +----------+ +----------+ Figure 11: NAT64; DNS64 in IPv6 hosts 3.2.3. Service Provider NAT64; DNS64 in the IPv4-only remote network - In this scenario, the service provider offers the NAT64 function - only. The remote IPv4-only network offers the DNS64 function. + In this scenario (Figure 12), the service provider offers the NAT64 + function only. The remote IPv4-only network offers the DNS64 + function. This is not common, and looks like doesn't make too much sense that a remote network, not deploying IPv6, is providing a DNS64 function. As in the case of the scenario depicted in Section 3.2.1, it will only work if both sides are using the WKP or the same NSP, so the same considerations apply. It can be also tuned to behave as in Section 3.1.1 This scenario still fails to solve the issue of IPv4 literal addresses or non-IPv6 compliant APIs. @@ -745,43 +765,44 @@ b. Literal/APIs: Are there applications using IPv4 literals or non- IPv6 compliant APIs? c. IPv4-only: Are there hosts or applications using IPv4-only? d. Foreign DNS: Is the scenario surviving if the user, Operating System, applications or devices change the DNS? e. DNS load opt. (DNS load optimization): Are there extra queries - that may impact DNS infrastructure?. + that may impact DNS infrastructure? f. Connect. opt. (Connection establishment delay optimization): Is the UE/CE issuing only the AAAA query or also an A query and waiting for both responses? In the next table, the columns represent each of the scenarios from the previous sections, by the figure number. The possible values are: o "-" Scenario "bad" for that criteria. o "+" Scenario "good" for that criteria. o "*" Scenario "bad" for that criteria, however it is typically - resolved, with the support of HEv2 ([RFC8305]). + resolved, with the support of Happy Eyeballs v2 ([RFC8305]). In some cases, "countermeasures", alternative or special configurations, may be available for the criteria designated as "bad". So, this comparison is considering a generic case, as a quick comparison guide. In some cases, a "bad" criterion is not necessarily a negative aspect, all it depends on the specific needs/ characteristics of the network where the deployment will take place. + For instance, in a network which has only IPv6-only hosts and apps using only DNS and IPv6-compliant APIs, there is no impact using only NAT64 and DNS64, but if the hosts may validate DNSSEC, that item is still relevant. +----------------+---+---+---+---+---+---+---+---+---+----+----+----+ | Item / Figure | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | +----------------+---+---+---+---+---+---+---+---+---+----+----+----+ | DNSSEC | - | - | - | - | - | - | - | + | + | + | + | + | +----------------+---+---+---+---+---+---+---+---+---+----+----+----+ @@ -811,40 +832,40 @@ built-in local address synthesis features, will provide a valid solution. Further to that, those scenarios will also keep working if the DNS configuration is modified. Clearly also, depending on if DNS64 is used or not, DNSSEC may be broken for those hosts doing DNSSEC validation. All the scenarios are good in terms of DNS load optimization, and in the case of 464XLAT it may provide an extra degree of optimization. Finally, all them are also good in terms of connection establishment delay optimization. However, in the case of 464XLAT without DNS64, - it requires the usage of HEv2. This is not an issue, as commonly it - is available in actual Operating Systems. + it requires the usage of Happy Eyeballs v2. This is not an issue, as + commonly it is available in actual Operating Systems. 4. Issues to be Considered This section reviews the different issues that an operator needs to consider towards a NAT64/464XLAT deployment, as they may bring to specific decision points about how to approach that deployment. 4.1. DNSSEC Considerations and Possible Approaches As indicated in Section 8 of [RFC6147] (DNS64, Security Considerations), because DNS64 modifies DNS answers and DNSSEC is designed to detect such modifications, DNS64 may break DNSSEC. - If a device connected to an IPv6-only WAN, queries for a domain name - in a signed zone, by means of a recursive name server that supports - DNS64, and the result is a synthesized AAAA record, and the recursive - name server is configured to perform DNSSEC validation and has a - valid chain of trust to the zone in question, it will + If a device connected to an IPv6-only access network, queries for a + domain name in a signed zone, by means of a recursive name server + that supports DNS64, and the result is a synthesized AAAA record, and + the recursive name server is configured to perform DNSSEC validation + and has a valid chain of trust to the zone in question, it will cryptographically validate the negative response from the authoritative name server. This is the expected DNS64 behavior: The recursive name server actually "lies" to the client device. However, in most of the cases, the client will not notice it, because generally, they don't perform validation themselves and instead, rely on the recursive name servers. A validating DNS64 resolver in fact, increase the confidence on the synthetic AAAA, as it has validated that a non-synthetic AAAA for sure, doesn't exists. However, if the client device is @@ -883,46 +904,47 @@ DNS64-needing world. As already indicated, the scenarios in the previous section, are in fact somehow simplified, looking at the worst possible case. Saying it in a different way: "trying to look for the most perfect approach". DNSSEC breach will not happen if the end-host is not doing validation. Existing previous studies seems to indicate that the figures of DNSSEC actually broken by using DNS64 will be around 1.7% - ([About-DNS64]) of the cases. However we can not negate that this - may increase, as DNSSEC deployment grows. Consequently, a decision - point for the operator must depend on "do I really care for that - percentage of cases and the impact in my helpdesk or can I provide - alternative solutions for them?". Some possible solutions may be - taken, as depicted in the next sections. + ([About-DNS64]) of the cases. However, we can't negate that this may + increase, as DNSSEC deployment grows. Consequently, a decision point + for the operator must depend on "do I really care for that percentage + of cases and the impact in my helpdesk or can I provide alternative + solutions for them?". Some possible solutions may be taken, as + depicted in the next sections. 4.1.1. Not using DNS64 A solution will be to avoid using DNS64, but as already indicated this is not possible in all the scenarios. The use of DNS64 is a key component for some networks, in order to comply with traffic performance metrics, monitored by some - governmental bodies and other institutions. + governmental bodies and other institutions ([FCC], [ARCEP]). One drawback of not having a DNS64 at the network side, is that is not possible to heuristically discover the NAT64 ([RFC7050]). Consequently, an IPv6 host behind the IPv6-only access network, will not be able to detect the presence of the NAT64 function, neither to learn the IPv6 prefix to be used for it, unless it is configured by alternative means. - The discovery of the IPv6 prefix could be solved by means of adding - the relevant AAAA records to the ipv4only.arpa. zone of the service - provider recursive servers, i.e., if using the WKP (64:ff9b::/96): + The discovery of the IPv6 prefix could be solved, as described in + [RFC7050], by means of adding the relevant AAAA records to the + ipv4only.arpa. zone, of the service provider recursive servers, i.e., + if using the WKP (64:ff9b::/96): ipv4only.arpa. SOA . . 0 0 0 0 0 ipv4only.arpa. NS . ipv4only.arpa. AAAA 64:ff9b::192.0.0.170 ipv4only.arpa. AAAA 64:ff9b::192.0.0.171 ipv4only.arpa. A 192.0.0.170 ipv4only.arpa. A 192.0.0.171 An alternative option to the above, is the use of DNS RPZ ([I-D.vixie-dns-rpz]) or equivalent functionalities. Note that this @@ -937,76 +959,86 @@ has evolved many considerations from that document. New options are being documented, such using Router Advertising ([I-D.ietf-6man-ra-pref64]) or DHCPv6 options ([I-D.li-intarea-nat64-prefix-dhcp-option]). It may be convenient the simultaneous support of several of the possible approaches, in order to ensure that clients with different ways to configure the NAT64 prefix, successfully obtain it. This is also convenient even if DNS64 is being used. + Of special relevance to this section is also + [I-D.cheshire-sudn-ipv4only-dot-arpa]. + 4.1.2. DNSSEC validator aware of DNS64 - In general, by default, DNS servers with DNS64 function, will not + In general, by default, DNS servers with DNS64 function will not synthesize AAAA responses if the DNSSEC OK (DO) flag was set in the - query. In this case, as only an A record is available, it means that - the CLAT will take the responsibility, as in the case of literal IPv4 - addresses, to keep that traffic flow end-to-end as IPv4, so DNSSEC is - not broken. However, this will not work if a CLAT function is not - present as the hosts will not be able to use IPv4 (scenarios without - 464XLAT). + query. + + In this case, as only an A record is available, if a CLAT function is + present, it means that the CLAT will take the responsibility, as in + the case of literal IPv4 addresses, to keep that traffic flow end-to- + end as IPv4, so DNSSEC is not broken. + + However, this will not work if a CLAT function is not present as the + hosts will not be able to use IPv4 (which is the case for all the + scenarios without 464XLAT). 4.1.3. Stub validator If the DO flag is set and the client device performs DNSSEC validation, and the Checking Disabled (CD) flag is set for a query, the DNS64 recursive server will not synthesize AAAA responses. In this case, the client could perform the DNSSEC validation with the A record and then synthesize the AAAA ([RFC6052]). For that to be possible, the client must have learned beforehand the NAT64 prefix using any of the available methods ([RFC7050], [RFC7225], [I-D.ietf-6man-ra-pref64], [I-D.li-intarea-nat64-prefix-dhcp-option]). This allows the client device to avoid using the DNS64 function and still use NAT64 even with DNSSEC. If the end-host is IPv4-only, this will not work if a CLAT function is not present (scenarios without 464XLAT). Some devices or Operating Systems may implement, instead of a CLAT, an equivalent function by using Bump-in-the-Host ([RFC6535]), - implemented as part of HEv2 (Section 7.1 of [RFC8305]). In this - case, the considerations in the above paragraphs are also applicable. + implemented as part of Happy Eyeballs v2 (Section 7.1 of [RFC8305]). + In this case, the considerations in the above paragraphs are also + applicable. 4.1.4. CLAT with DNS proxy and validator If a CE includes CLAT support and also a DNS proxy, as indicated in Section 6.4 of [RFC6877], the CE could behave as a stub validator on behalf of the client devices. Then, following the same approach described in the Section 4.1.3, the DNS proxy actually will "lie" to the client devices, which in most of the cases will not notice it, unless they perform validation by themselves. Again, this allow the client devices to avoid using the DNS64 function and still use NAT64 with DNSSEC. Once more, this will not work without a CLAT function (scenarios without 464XLAT). 4.1.5. ACL of clients In cases of dual-stack clients, the AAAA queries typically take preference over A queries. If DNS64 is enabled for those clients, - will never get A records, even for IPv4-only servers. As a - consequence, if the IPv4-only servers are in the path before the - NAT64 function, the clients will never reach them. If DNSSEC is - being used for all those flows, specific addresses or prefixes can be - left-out of the DNS64 synthesis by means of ACLs. + will never get A records, even for IPv4-only servers. + + As a consequence, in cases where there are IPv4-only servers, and + those are located in the path before the NAT64 function, the clients + will not be able to reach them. If DNSSEC is being used for all + those flows, specific addresses or prefixes can be left-out of the + DNS64 synthesis by means of ACLs. Once more, this will not work without a CLAT function (scenarios without 464XLAT). 4.1.6. Mapping-out IPv4 addresses If there are well-known specific IPv4 addresses or prefixes using DNSSEC, they can be mapped-out of the DNS64 synthesis. Even if this is not related to DNSSEC, this "mapping-out" feature is @@ -1077,33 +1109,34 @@ device is doing a local address synthesis (see Section 7.1 of [RFC8305]). 4.4. Foreign DNS Clients, devices or applications in a service provider network, may use DNS servers from other networks. This may be the case either if individual applications use their own DNS server, the Operating System itself or even the CE, or combinations of the above. - Those "foreign" DNS servers may not support DNS64, which will mean - that those scenarios that require a DNS64 may not work. However, if - a CLAT function is available, the considerations in Section 4.3 will - apply. + Those "foreign" DNS servers may not support DNS64, which as a + consequence, will mean that those scenarios that require a DNS64 may + not work. However, if a CLAT function is available, the + considerations in Section 4.3 will apply. In the case that the foreign DNS supports the DNS64 function, we may be in the situation of providing incorrect configurations parameters, for example, un-matching WKP or NSP, or a case such the one described in Section 3.2.3. Having a CLAT function, even if using foreign DNS without a DNS64 function, ensures that everything will work, so the CLAT must be considered as an advantage even against user configuration errors. + The cost of this, is that all the traffic will use a double translation (NAT46 at the CLAT and NAT64 at the operator network), unless there is support for EAM (Section 4.9). An exception to that is the case when there is a CLAT function at the CE, which is not able to obtain the correct configuration parameters (again, un-matching WKP or NSP). However, it needs to be emphasized, that if there is not a CLAT function (scenarios without 464XLAT), an external DNS without DNS64 @@ -1101,33 +1134,41 @@ translation (NAT46 at the CLAT and NAT64 at the operator network), unless there is support for EAM (Section 4.9). An exception to that is the case when there is a CLAT function at the CE, which is not able to obtain the correct configuration parameters (again, un-matching WKP or NSP). However, it needs to be emphasized, that if there is not a CLAT function (scenarios without 464XLAT), an external DNS without DNS64 support, will disallow any access to IPv4-only destination networks, - and will not guarantee DNSSEC, so will behave as in the - Section 3.2.1. + and will not guarantee the correct DNSSEC validation, so will behave + as in the Section 3.2.1. + + In summary, it can be said, that the consequences of the use of + foreign DNS depend very much in each specific case. However, in + general, if a CLAT function is present, most of the time, there will + not be any. In the other cases, generally, the access to + IPv6-enabled services is still guaranteed for IPv6-enabled hosts, but + not for IPv4-only hosts, neither the access to IPv4-only services for + any hosts in the network. The causes of "foreign DNS" could be classified in three main categories, as depicted in the following sub-sections. -4.4.1. Manual Configuration of Foreign DNS +4.4.1. Manual Configuration of DNS It is becoming increasingly common that end-users or even devices or applications configure alternative DNS in their Operating Systems, and sometimes in CEs. -4.4.2. DNS Privacy +4.4.2. DNS Privacy/Encryption Mechanisms A new trend is for clients or applications to use mechanisms for DNS privacy/encryption, such as DNS over TLS ([RFC7858]), DNS over DTLS ([RFC8094]), DNS queries over HTTPS ([RFC8484]) or DNS over QUIC ([I-D.huitema-quic-dnsoquic]). Those are commonly cited as DoT, DoH and DoQ. Those DNS privacy/encryption options, currently are typically provided by the applications, not the Operating System vendors. At the time of writing this document, at least DoT and DoH standards @@ -1171,29 +1212,29 @@ their state. Using an NSP could simplify that. d. If DNS64 is required and users, devices, Operating Systems or applications may change their DNS configuration, and deliberately choose an alternative DNS64 function, most probably alternative DNS64 will use by default the WKP. In that case, if an NSP is used by the NAT64 function, clients will not be able to use the operator NAT64 function, which will break connectivity to IPv4-only destinations. -4.6. IPv4 literals and old APIs +4.6. IPv4 literals and non-IPv6 Compliant APIs A host or application using literal IPv4 addresses or older APIs, - behind a network with IPv6-only access, will not work unless any of - the following alternatives is provided: + which aren't IPv6 compliant, behind a network with IPv6-only access, + will not work unless any of the following alternatives is provided: o CLAT (or equivalent function). - o HEv2 (Section 7.1, [RFC8305]). + o Happy Eyeballs v2 (Section 7.1, [RFC8305]). o Bump-in-the-Host ([RFC6535]) with a DNS64 function. Those alternatives will solve the problem for an end-host. However, if that end-hosts is providing "tethering" or an equivalent service to other hosts, that needs to be considered as well. In other words, in a case of a cellular network, it resolves the issue for the UE itself, but may be not the case for hosts behind it. Otherwise, the support of 464XLAT is the only valid and complete @@ -1252,57 +1293,60 @@ 4.10. Incoming Connections The use of NAT64, in principle, disallows IPv4 incoming connections, which may be still needed for IPv4-only peer-to-peer applications. However, there are several alternatives that resolve this issue: a. STUN ([RFC5389]), TURN ([RFC5766]) and ICE ([RFC8445]) are commonly used by peer-to-peer applications in order to allow incoming connections with IPv4 NAT. In the case of NAT64, they - work as well. + work as well. Note also the relevance of + [I-D.ietf-tram-turnbis]. b. PCP ([RFC6887]) allows a host to control how incoming IPv4 and IPv6 packets are translated and forwarded. A NAT64 may implement PCP to allow this service. c. EAM ([RFC7757]) may also be used in order to configure explicit mappings for customers that require them. This is used for example by SIIT-DC ([RFC7755]) and SIIT-DC-DTM ([RFC7756]). 5. Summary of Deployment Recommendations for NAT64/464XLAT NAT64/464XLAT has demonstrated to be a valid choice in several scenarios (IPv6-IPv4 and IPv4-IPv6-IPv4), with hundreds of millions - of users, offering different choices of deployment, depending on each - network case, needs and requirements. Despite that, this document is - not an explicit recommendation for using this choice versus other - IPv4aaS transition mechanisms. Instead, this document is a guide - that facilitates evaluating a possible implementation of + of users, being the predominant mechanism in the majority of the + cellular networks (which account for hundreds of millions of users). + NAT64/464XLAT offer different choices of deployment, depending on + each network case, needs and requirements. Despite that, this + document is not an explicit recommendation for using this choice + versus other IPv4aaS transition mechanisms. Instead, this document + is a guide that facilitates evaluating a possible implementation of NAT64/464XLAT and key decision points about specific design considerations for its deployment. Depending on the specific requirements of each deployment case, DNS64 may be a required function, while in other cases the adverse effects may be counterproductive. Similarly, in some cases a NAT64 function, together with a DNS64 function, may be a valid solution, when there is a certainty that IPv4-only hosts or applications do not need to be supported (Section 4.6 and Section 4.7). However, in other cases (i.e. IPv4-only devices or applications need to be supported), the limitations of NAT64/DNS64, may suggest the operator to look into 464XLAT as a more complete solution. In the case of broadband managed networks (where the CE is provided or suggested/supported by the operator), in order to fully support the actual user needs (IPv4-only devices and applications, usage of - IPv4 literals and old APIs), the 464XLAT scenario should be - considered. In that case, it must support a CLAT function. + IPv4 literals and non-IPv6 compliant APIs), the 464XLAT scenario + should be considered. In that case, it must support a CLAT function. If the operator provides DNS services, in order to increase performance by reducing the double translation for all the IPv4 traffic, they may support a DNS64 function and avoid, as much as possible, breaking DNSSEC. In this case, if the DNS service is offering DNSSEC validation, then it must be in such way that it is aware of the DNS64. This is considered the simpler and safer approach, and may be combined as well with other recommendations described in this document: @@ -1430,84 +1474,91 @@ An example of that is the IETF meetings network itself, where both NAT64 and DNS64 functions are provided, presenting in this case the same issues as per Section 3.1.1. If there is a CLAT function in the IETF network, then there is no need to use DNS64 and it falls under the considerations of Section 3.1.3. Both scenarios have been tested and verified already in the IETF network itself. Next figures are only meant to represent a few of the possible scenarios, not pretending to be the only feasible ones. - The following figure provides an example of an IPv6-only enterprise - network connected with dual-stack to Internet and using local NAT64 - and DNS64 functions. + Figure 14 provides an example of an IPv6-only enterprise network + connected with dual-stack to Internet and using local NAT64 and DNS64 + functions. +----------------------------------+ | Enterprise Network | | +----------+ +----------+ | +----------+ | | IPv6 | | NAT64 | | | IPv4 | | | only +--------+ + | +-------+ + | | | LANs | | DNS64 | | | IPv6 | | +----------+ +----------+ | +----------+ +----------------------------------+ Figure 14: IPv6-only enterprise with NAT64 and DNS64 - The following figure provides an example of a dual-stack (DS) - enterprise network connected with dual-stack (DS) to Internet and - using a CLAT function, without a DNS64 function. + Figure 15 provides an example of a dual-stack (DS) enterprise network + connected with dual-stack (DS) to Internet and using a CLAT function, + without a DNS64 function. +----------------------------------+ | Enterprise Network | | +----------+ +----------+ | +----------+ | | IPv6 | | | | | IPv4 | | | + +--------+ NAT64 | +-------+ + | | | CLAT | | | | | IPv6 | | +----------+ +----------+ | +----------+ +----------------------------------+ Figure 15: DS enterprise with CLAT, DS Internet, without DNS64 - Finally, the following figure provides an example of an IPv6-only - provider with a NAT64 function, and a dual-stack (DS) enterprise - network by means of their own CLAT function, without a DNS64 - function. + Finally, Figure 16 provides an example of an IPv6-only provider with + a NAT64 function, and a dual-stack (DS) enterprise network by means + of their own CLAT function, without a DNS64 function. +----------------------------------+ | Enterprise Network | | +----------+ +----------+ | +----------+ | | IPv6 | | | | IPv6 | | | | + +--------+ CLAT | +--------+ NAT64 | | | IPv4 | | | | only | | | +----------+ +----------+ | +----------+ +----------------------------------+ Figure 16: DS enterprise with CLAT, IPv6-only Access, without DNS64 7. Security Considerations This document does not have new specific security considerations beyond those already reported by each of the documents cited. + It should be remarked that the use of a DNS64 function has equivalent + privacy considerations as in the case of a regular DNS, either + located in the service provider or an external one. + 8. IANA Considerations This document does not have any new specific IANA considerations. Note: This section is assuming that https://www.rfc- editor.org/errata/eid5152 is resolved, otherwise, this section may include the required text to resolve the issue. + Alternatively, this could be fixed also by + [I-D.cheshire-sudn-ipv4only-dot-arpa]. + 9. Acknowledgements The author would like to acknowledge the inputs of Gabor Lencse, Andrew Sullivan, Lee Howard, Barbara Stark, Fred Baker, Mohamed - Boucadair, Alejandro D'Egidio, Dan Wing and Mikael Abrahamsson. + Boucadair, Alejandro D'Egidio, Dan Wing, Mikael Abrahamsson and Eric + Vyncke. Conversations with Marcelo Bagnulo, one of the co-authors of NAT64 and DNS64, as well as several emails in mailing lists from Mark Andrews, have been very useful for this work. Christian Huitema inspired working in this document by suggesting that DNS64 should never be used, during a discussion regarding the deployment of CLAT in the IETF network. 10. ANNEX A: Example of Broadband Deployment with 464XLAT @@ -1624,25 +1675,24 @@ Figure 18: CE setup with built-in CLAT without DNS64 In this case, the discovery of the PLAT prefix needs to be arranged as indicated in Section 4.1.1. In this case, the CE doesn't have a built-in CLAT function, or the customer can choose to setup the IPv6 operator-managed CE in bridge mode (and optionally use an external router), or for example, there is an access technology that requires some kind of media converter (ONT for FTTH, Cable-Modem for DOCSIS, etc.), the complete setup will - look as in the next figure. Obviously, there will be some - intermediate configuration steps for the bridge, depending on the - specific access technology/protocols, which should not modify the - steps already described in the previous cases for the CLAT function - configuration. + look as in Figure 19. Obviously, there will be some intermediate + configuration steps for the bridge, depending on the specific access + technology/protocols, which should not modify the steps already + described in the previous cases for the CLAT function configuration. +-------+ .-----. .-----. | | / \ / \ | Res./ | / IPv6- \ .-----. / IPv4- \ | SOHO +--( only )--( NAT64 )--( only ) | | \ flow / `-----' \ flow / | IPv6 | \ / \ / | CE | `--+--' `--+--' | Bridge| | | | | +---+----+ +---+----+ @@ -1684,20 +1734,23 @@ o [RFC7915] for the NAT46 function. o [RFC7050] for the PLAT prefix discovery. o [RFC7225] for the PLAT prefix discovery if PCP is supported. o [I-D.ietf-6man-ra-pref64] for the PLAT prefix discovery by means of Router Advertising. + o [I-D.li-intarea-nat64-prefix-dhcp-option] for the PLAT prefix + discovery by means of DHCP. + o If stateless NAT46 is supported, a mechanism to ensure that multiple /64 are available, such as DHCPv6-PD [RFC8415]. There are several OpenSource implementations of CLAT, such as: o Android: https://github.com/ddrown/android_external_android-clat. o Jool: https://www.jool.mx. o Linux: https://github.com/toreanderson/clatd. @@ -1753,23 +1806,29 @@ 17. ANNEX H: Changes from -05 to -06 Section to be removed after WGLC. Significant updates are: 1. Corrected EAMT to EAM. 2. Typos and nits. 3. New considerations regarding incoming connections. -18. References +18. ANNEX H: Changes from -06 to -07 -18.1. Normative References + Section to be removed after WGLC. Significant updates are: + + 1. Inputs/clarifications from IESG review. + +19. References + +19.1. Normative References [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . @@ -1870,71 +1929,94 @@ [RFC8445] Keranen, A., Holmberg, C., and J. Rosenberg, "Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal", RFC 8445, DOI 10.17487/RFC8445, July 2018, . [RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018, . -18.2. Informative References +19.2. Informative References [About-DNS64] Linkova, J., "Let's talk about IPv6 DNS64 & DNSSEC", 2016, . + [ARCEP] ARCEP, "Service client des operateurs : les mesures de + qualite de service", 2018, . + [DNS64-Benchm] Lencse, G. and Y. Kadobayashi, "Benchmarking DNS64 Implementations: Theory and Practice", Computer Communications , vol. 127, no. 1, pp. 61-74, DOI 10.1016/j.comcom.2018.05.005, September 2018. [DNS64-BM-Meth] Lencse, G., Georgescu, M., and Y. Kadobayashi, "Benchmarking Methodology for DNS64 Servers", Computer Communications , vol. 109, no. 1, pp. 162-175, DOI 10.1016/j.comcom.2017.06.004, September 2017. + [FCC] FCC, "Measuring Broadband America Mobile 2013-2018 + Coarsened Data", 2018, . + [I-D.bp-v6ops-ipv6-ready-dns-dnssec] Byrne, C. and J. Palet, "IPv6-Ready DNS/DNSSSEC Infrastructure", draft-bp-v6ops-ipv6-ready-dns-dnssec-00 (work in progress), October 2018. + [I-D.cheshire-sudn-ipv4only-dot-arpa] + Cheshire, S. and D. Schinazi, "Special Use Domain Name + 'ipv4only.arpa'", draft-cheshire-sudn-ipv4only-dot-arpa-14 + (work in progress), November 2018. + [I-D.huitema-quic-dnsoquic] Huitema, C., Shore, M., Mankin, A., Dickinson, S., and J. Iyengar, "Specification of DNS over Dedicated QUIC Connections", draft-huitema-quic-dnsoquic-06 (work in progress), March 2019. [I-D.ietf-6man-ra-pref64] - Colitti, L., Kline, E., and J. Linkova, "Discovering - PREF64 in Router Advertisements", draft-ietf-6man-ra- - pref64-00 (work in progress), March 2019. + Colitti, L. and J. Linkova, "Discovering PREF64 in Router + Advertisements", draft-ietf-6man-ra-pref64-01 (work in + progress), June 2019. + + [I-D.ietf-tram-turnbis] + K, R., Johnston, A., Matthews, P., and J. Rosenberg, + "Traversal Using Relays around NAT (TURN): Relay + Extensions to Session Traversal Utilities for NAT (STUN)", + draft-ietf-tram-turnbis-27 (work in progress), June 2019. [I-D.li-intarea-nat64-prefix-dhcp-option] Li, L., Cui, Y., Liu, C., Wu, J., Baker, F., and J. Palet, "DHCPv6 Options for Discovery NAT64 Prefixes", draft-li- intarea-nat64-prefix-dhcp-option-02 (work in progress), April 2019. [I-D.lmhp-v6ops-transition-comparison] Lencse, G., Palet, J., Howard, L., Patterson, R., and I. Farrer, "Pros and Cons of IPv6 Transition Technologies for - IPv4aaS", draft-lmhp-v6ops-transition-comparison-02 (work - in progress), January 2019. + IPv4aaS", draft-lmhp-v6ops-transition-comparison-03 (work + in progress), July 2019. [I-D.palet-v6ops-464xlat-opt-cdn-caches] - Palet, J. and A. D'Egidio, "464XLAT Optimization for CDNs/ - Caches", draft-palet-v6ops-464xlat-opt-cdn-caches-01 (work - in progress), March 2019. + Palet, J. and A. D'Egidio, "464XLAT Optimization", draft- + palet-v6ops-464xlat-opt-cdn-caches-02 (work in progress), + June 2019. [I-D.vixie-dns-rpz] Vixie, P. and V. Schryver, "DNS Response Policy Zones (RPZ)", draft-vixie-dns-rpz-04 (work in progress), December 2016. [RFC6889] Penno, R., Saxena, T., Boucadair, M., and S. Sivakumar, "Analysis of Stateful 64 Translation", RFC 6889, DOI 10.17487/RFC6889, April 2013, .