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Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'TBD' is mentioned on line 267, but not defined Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPv6 Operations T. Anderson 3 Internet-Draft Redpill Linpro 4 Intended status: Standards Track May 12, 2017 5 Expires: November 13, 2017 7 Local-use IPv4/IPv6 Translation Prefix 8 draft-ietf-v6ops-v4v6-xlat-prefix-01 10 Abstract 12 This document reserves the IPv6 prefix 64:ff9b:1::/48 for local use 13 within domains that enable IPv4/IPv6 translation mechanisms. 15 Status of This Memo 17 This Internet-Draft is submitted in full conformance with the 18 provisions of BCP 78 and BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF). Note that other groups may also distribute 22 working documents as Internet-Drafts. The list of current Internet- 23 Drafts is at http://datatracker.ietf.org/drafts/current/. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 This Internet-Draft will expire on November 13, 2017. 32 Copyright Notice 34 Copyright (c) 2017 IETF Trust and the persons identified as the 35 document authors. All rights reserved. 37 This document is subject to BCP 78 and the IETF Trust's Legal 38 Provisions Relating to IETF Documents 39 (http://trustee.ietf.org/license-info) in effect on the date of 40 publication of this document. Please review these documents 41 carefully, as they describe your rights and restrictions with respect 42 to this document. Code Components extracted from this document must 43 include Simplified BSD License text as described in Section 4.e of 44 the Trust Legal Provisions and are provided without warranty as 45 described in the Simplified BSD License. 47 Table of Contents 49 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 50 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 51 3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 2 52 4. Why 64:ff9b:1::/48? . . . . . . . . . . . . . . . . . . . . . 3 53 4.1. Prefix Length . . . . . . . . . . . . . . . . . . . . . . 3 54 4.2. Prefix Value . . . . . . . . . . . . . . . . . . . . . . 4 55 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 4 56 6. Checksum Neutrality . . . . . . . . . . . . . . . . . . . . . 5 57 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 58 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 59 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 60 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 61 9.2. Informative References . . . . . . . . . . . . . . . . . 7 62 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7 63 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 65 1. Introduction 67 This document reserves 64:ff9b:1::/48 for local use within domains 68 that enable IPv4/IPv6 translation mechanisms. This facilitates the 69 co-existence of multiple IPv4/IPv6 translation mechanisms in the same 70 network without requiring the use of a Network-Specific Prefix 71 assigned from the operator's allocated global unicast address space. 73 2. Terminology 75 This document makes use of the following terms: 77 Network-Specific Prefix (NSP) 78 A globally unique prefix assigned by a network operator for use 79 with an IPv4/IPv6 translation mechanism [RFC6052]. 81 Well-Known Prefix (WKP) 82 The prefix 64:ff9b::/96, which is reserved for use with the 83 [RFC6052] IPv4/IPv6 address translation algorithm. 85 3. Problem Statement 87 Since the WKP 64:ff9b::/96 was reserved by [RFC6052], several new 88 IPv4/IPv6 translation mechanisms have been defined by the IETF, such 89 as [RFC6146] and [RFC7915]. These mechanisms target various 90 different use cases. An operator might therefore wish to make use of 91 several of them simultaneously. 93 The WKP is reserved specifically for use with the algorithm specified 94 in [RFC6052]. More recent IETF documents describe IPv4/IPv6 95 translation mechanisms that use different algorithms. An operator 96 deploying such mechanisms can not make use of the WKP in a legitimate 97 fashion. 99 Also, because the WKP is a /96, an operator preferring to use the WKP 100 over an NSP can only do so for only one of their IPv4/IPv6 101 translation mechanisms. All others must necessarily use an NSP. 103 Section 3.1 of [RFC6052] imposes certain restrictions on the use of 104 the WKP, such as forbidding its use in combination with private IPv4 105 addresses [RFC1918]. These restrictions might conflict with the 106 operator's desired use of an IPv4/IPv6 translation mechanism. 108 In summary, there is a need for a local-use prefix that facilitates 109 the co-existence of multiple IPv4/IPv6 translation mechanisms in a 110 single network domain, as well as the deployment of translation 111 mechanisms that do not use the [RFC6052] algorithm or adhere to its 112 usage restrictions. 114 4. Why 64:ff9b:1::/48? 116 4.1. Prefix Length 118 One of the primary goals of this document is to facilitate multiple 119 simultaneous deployments of IPv4/IPv6 translation mechanisms in a 120 single network. The first criterion is therefore that the prefix 121 length chosen must be shorter than the prefix length used by any 122 individual translation mechanism. 124 The second criterion is that the prefix length chosen is a multiple 125 of 16. This ensures the prefix ends on a colon boundary when 126 representing it in text, easing operator interaction with it. 128 The [RFC6052] algorithm specifies IPv4/IPv6 translation prefixes as 129 short as /32. In order to facilitate multiple instances of 130 translation mechanisms using /32s, while at the same time aligning on 131 a 16-bit boundary, it would be necessary to reserve a /16. Doing so, 132 however, was considered as too wasteful by the IPv6 Operations 133 working group. 135 The shortest translation prefix that was reported to the IPv6 136 Operations working group to be deployed in a live network was /64. 137 The longest 16-bit-aligned prefix length that can accommodate 138 multiple instances of /64 is /48. The prefix length of /48 was 139 therefore chosen, as it satisfies both the criteria above, while at 140 the same time avoids wasting too much of the IPv6 address space. 142 4.2. Prefix Value 144 It is desirable to minimise the amount of additional "pollution" in 145 the unallocated IPv6 address space caused by the reservation made by 146 this document. Ensuring the reserved prefix is adjacent to the 147 64:ff9b::/96 WKP already reserved by [RFC6052] accomplishes this. 149 Given the previous decision to use a prefix length of /48, this 150 leaves two options: 64:ff9a:ffff:ffff::/48 and 64:ff9b:1::/48. 152 64:ff9a:ffff:ffff::/48 has the benefit that it is completely adjacent 153 to the [RFC6052] WKP. That is, 64:ff9a:ffff:ffff::/48 and 154 64:ff9b::/96 combines to form a uninterrupted range of IPv6 addresses 155 starting with 64:ff9a:ffff:ffff:: and ending with 64:ff9b::ffff:ffff. 157 64:ff9b:1::/48 is, on the other hand, not completely adjacent to 158 64:ff9b::/96. The range starting with 64:ff9b::1:0:0 and ending with 159 64:ff9b:0:ffff:ffff:ffff:ffff:ffff would remain unallocated. 161 This particular drawback is, however, balanced by the fact that the 162 smallest possible aggregate prefix that covers both the [RFC6052] WKP 163 and 64:ff9a:ffff:ffff::/48 is much larger than the smallest possible 164 aggregate prefix that covers both the [RFC6052] WKP and 165 64:ff9b:1::/48. These aggregate prefixes are 64:ff9a::/31 and 166 64:ff9b::/47, respectively. IPv6 address space is allocated using 167 prefixes rather than address ranges, so it could be argued that 168 64:ff9b:1::/48 is the option that would cause special-use prefixes 169 reserved for IPv4/IPv6 translation to "pollute" the minimum possible 170 amount of unallocated IPv6 address space. 172 Finally, 64:ff9b:1::/48 also has the advantage that its textual 173 representation is considerably shorter than 64:ff9a:ffff:ffff::/48. 174 While this might seem insignificant, the preference human network 175 operators have for addresses that are simple to type should not be 176 underestimated. 178 After weighing the above pros and cons, 64:ff9b:1::/48 was chosen. 180 5. Deployment Considerations 182 64:ff9b:1::/48 is intended as a technology-agnostic and generic 183 reservation. A network operator may freely use it in combination 184 with any kind of IPv4/IPv6 translation mechanism deployed within 185 their network. 187 By default, IPv6 nodes and applications must not treat IPv6 addresses 188 within 64:ff9b:1::/48 different from other globally scoped IPv6 189 addresses. In particular, they must not make any assumptions 190 regarding the syntax or properties of those addresses (e.g., the 191 existence and location of embedded IPv4 addresses), or the type of 192 associated translation mechanism (e.g., whether it is stateful or 193 stateless). 195 64:ff9b:1::/48 or any more-specific prefix may only be used in inter- 196 domain routing if done in accordance with the rules described in 197 Section 3.2 of [RFC6052]. 199 Note that 64:ff9b:1::/48 (or any more-specific prefix) is distinct 200 from the WKP 64:ff9b::/96. Therefore, the restrictions on the use of 201 the WKP described in Section 3.1 of [RFC6052] do not apply to the use 202 of 64:ff9b:1::/48. 204 Operators tempted to use the covering aggregate prefix 64:ff9b::/47 205 to refer to all special-use prefixes currently reserved for IPv4/IPv6 206 translation should be warned that this aggregate includes a range of 207 unallocated addresses (Section 4.2) that the IETF could potentially 208 reserve in the future for entirely different purposes. 210 6. Checksum Neutrality 212 Use of 64:ff9b:1::/48 does not in itself guarantee checksum 213 neutrality, as many of the IPv4/IPv6 translation algorithms it can be 214 used with are fundamentally incompatible with checksum-neutral 215 address translations. 217 Section 4.1 of [RFC6052] contains further discussion about IPv4/IPv6 218 translation and checksum neutrality. 220 The Stateless IP/ICMP Translation algorithm [RFC7915] is one well- 221 known algorithm that can operate in a checksum-neutral manner, when 222 using the [RFC6052] algorithm for all of its address translations. 223 However, in order to attain checksum neutrality it is imperative that 224 the translation prefix is chosen carefully. Specifically, in order 225 for a 96-bit [RFC6052] prefix to be checksum neutral, all the six 226 16-bit words in the prefix must add up to a multiple of 0xffff. 228 The following non-exhaustive list contains examples of translation 229 prefixes that are checksum neutral when used with the [RFC7915] and 230 [RFC6052] algorithms: 232 o 64:ff9b:1:fffe::/96 234 o 64:ff9b:1:fffd:1::/96 236 o 64:ff9b:1:fffc:2::/96 237 o 64:ff9b:1:abcd:0:5431::/96 239 7. IANA Considerations 241 (Note to the RFC Editor: Please replace occurrences of "TBD" in this 242 section with the assigned RFC number of this document and delete this 243 note.) 245 The IANA is requested to add the following entry to the IPv6 Special- 246 Purpose Address Registry: 248 +----------------------+---------------------+ 249 | Attribute | Value | 250 +----------------------+---------------------+ 251 | Address Block | 64:ff9b:1::/48 | 252 | Name | IPv4-IPv6 Translat. | 253 | RFC | (TBD) | 254 | Allocation Date | (TBD) | 255 | Termination Date | N/A | 256 | Source | True | 257 | Destination | True | 258 | Forwardable | True | 259 | Global | False | 260 | Reserved-by-Protocol | False | 261 +----------------------+---------------------+ 263 The IANA is furthermore requested to add the following footnote to 264 the 0000::/8 entry of the Internet Protocol Version 6 Address Space 265 registry: 267 64:ff9b:1::/48 reserved for Local-use IPv4/IPv6 Translation [TBD] 269 8. Security Considerations 271 The reservation of 64:ff9b:1::/48 is not known to cause any new 272 security considerations beyond those documented in Section 5 of 273 [RFC6052]. 275 9. References 277 9.1. Normative References 279 [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. 280 Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, 281 DOI 10.17487/RFC6052, October 2010, 282 . 284 9.2. Informative References 286 [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., 287 and E. Lear, "Address Allocation for Private Internets", 288 BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, 289 . 291 [RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful 292 NAT64: Network Address and Protocol Translation from IPv6 293 Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, 294 April 2011, . 296 [RFC7915] Bao, C., Li, X., Baker, F., Anderson, T., and F. Gont, 297 "IP/ICMP Translation Algorithm", RFC 7915, 298 DOI 10.17487/RFC7915, June 2016, 299 . 301 Acknowledgements 303 The author would like to thank Fred Baker, Mohamed Boucadair, Brian E 304 Carpenter, Pier Carlo Chiodi, Joe Clarke, David Farmer, Warren 305 Kumari, Holger Metschulat, Federico Santandrea and David Schinazi for 306 contributing to the creation of this document. 308 Author's Address 310 Tore Anderson 311 Redpill Linpro 312 Vitaminveien 1A 313 0485 Oslo 314 Norway 316 Phone: +47 959 31 212 317 Email: tore@redpill-linpro.com 318 URI: http://www.redpill-linpro.com