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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 268, 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 Updates: 6890 (if approved) March 9, 2017 5 Intended status: Standards Track 6 Expires: September 10, 2017 8 Local-use IPv4/IPv6 Translation Prefix 9 draft-ietf-v6ops-v4v6-xlat-prefix-00 11 Abstract 13 This document reserves the IPv6 prefix 64:ff9b:1::/48 for local use 14 within domains that enable IPv4/IPv6 translation mechanisms. This 15 document updates RFC6890. 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at http://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on September 10, 2017. 34 Copyright Notice 36 Copyright (c) 2017 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 53 3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 2 54 4. Why 64:ff9b:1::/48? . . . . . . . . . . . . . . . . . . . . . 3 55 4.1. Prefix Length . . . . . . . . . . . . . . . . . . . . . . 3 56 4.2. Prefix Value . . . . . . . . . . . . . . . . . . . . . . 4 57 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 4 58 6. Checksum Neutrality . . . . . . . . . . . . . . . . . . . . . 5 59 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 60 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6 61 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 62 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 63 9.2. Informative References . . . . . . . . . . . . . . . . . 7 64 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 7 65 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 67 1. Introduction 69 This document reserves 64:ff9b:1::/48 for local use within domains 70 that enable IPv4/IPv6 translation mechanisms. This facilitates the 71 co-existence of multiple IPv4/IPv6 translation mechanisms in the same 72 network without requiring the use of a Network-Specific Prefix 73 assigned from the operator's allocated global unicast address space. 75 2. Terminology 77 This document makes use of the following terms: 79 Network-Specific Prefix (NSP) 80 A globally unique prefix assigned by a network operator for use 81 with an IPv4/IPv6 translation mechanism [RFC6052]. 83 Well-Known Prefix (WKP) 84 The prefix 64:ff9b::/96, which is reserved for use with the 85 [RFC6052] IPv4/IPv6 address translation algorithm. 87 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 88 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 89 document are to be interpreted as described in [RFC2119]. 91 3. Problem Statement 93 Since the WKP 64:ff9b::/96 was reserved by [RFC6052], several new 94 IPv4/IPv6 translation mechanisms have been defined by the IETF. 95 These mechanisms target various different use cases. An operator 96 might therefore wish to make use of several of them simultaneously. 98 The WKP is reserved specifically for use with the algorithm specified 99 in [RFC6052]. More recent IETF documents describe IPv4/IPv6 100 translation mechanisms that use different algorithms. An operator 101 deploying such mechanisms can not make use of the WKP in a legitimate 102 fashion. 104 Also, because the WKP is a /96, an operator preferring to use a WKP 105 over an NSP can only do so for only one of his IPv4/IPv6 translation 106 mechanisms. All others must necessarily use an NSP. 108 Section 3.1 of [RFC6052] imposes certain restrictions on the use of 109 the WKP, such as forbidding its use in combination with private IPv4 110 addresses [RFC1918]. These restrictions might conflict with the 111 operator's desired use of an IPv4/IPv6 translation mechanism. 113 In summary, there is a need for a local-use prefix that facilitates 114 the co-existence of multiple IPv4/IPv6 translation mechanisms in a 115 single network domain, as well as the deployment of translation 116 mechanisms that do not use the [RFC6052] algorithm or adhere to its 117 usage restrictions. 119 4. Why 64:ff9b:1::/48? 121 4.1. Prefix Length 123 One of the primary goals of this document is to facilitate multiple 124 simultaneous deployments of IPv4/IPv6 translation mechanisms in a 125 single network. The first criterion is therefore that the prefix 126 length chosen must be shorter than the prefix length used by any 127 individual translation mechanism. 129 The second criterion is that the prefix length chosen is is a 130 multiple of 16. This ensures the prefix ends on a colon boundary 131 when representing it in text, easing operator interaction with it. 133 The [RFC6052] algorithm specifies IPv4/IPv6 translation prefixes as 134 short as /32. In order to facilitate multiple instances of 135 translation mechanisms using /32s, while at the same time aligning on 136 a 16-bit boundary, it would be necessary to reserve a /16. Doing so 137 was however considered as too wasteful by the IPv6 Operations working 138 group. 140 The shortest translation prefix that was reported to the IPv6 141 Operations working group to be deployed in a live network was /64. 142 The longest 16-bit-aligned prefix length that can accommodate 143 multiple instances of /64 is /48. The prefix length of /48 was 144 therefore chosen, as it satisfies both the criteria above, while at 145 the same time avoids wasting too much of the IPv6 address space. 147 4.2. Prefix Value 149 It is desirable to minimise the amount of additional "pollution" in 150 the unallocated IPv6 address space caused by the reservation made by 151 this document. Ensuring the reserved prefix is adjacent to the 152 64:ff9b::/96 WKP already reserved by [RFC6052] accomplishes this. 154 Given the previous decision to use a prefix length of /48, this 155 leaves two options: 64:ff9a:ffff:ffff::/48 and 64:ff9b:1::/48. 157 64:ff9a:ffff:ffff::/48 has the benefit that it is completely adjacent 158 to the [RFC6052] WKP. That is, 64:ff9a:ffff:ffff::/48 and 159 64:ff9b::/96 combines to form a uninterrupted range of IPv6 addresses 160 starting with 64:ff9a:ffff:ffff:: and ending with 64:ff9b::ffff:ffff. 162 64:ff9b:1::/48 is, on the other hand, not completely adjacent to 163 64:ff9b::/96. The range starting with 64:ff9b::1:0:0 and ending with 164 64:ff9b:0:ffff:ffff:ffff:ffff:ffff would remain unallocated. 166 This particular drawback is, however, balanced by the fact that the 167 smallest possible aggregate prefix that covers both the [RFC6052] WKP 168 and 64:ff9a:ffff:ffff::/48 is much larger than the smallest possible 169 aggregate prefix that covers both the [RFC6052] WKP and 170 64:ff9b:1::/96. These aggregate prefixes are 64:ff9a::/31 and 171 64:ff9b::/47, respectively. IPv6 address space is allocated using 172 prefixes rather than address ranges, so it could be argued that 173 64:ff9b:1::/96 is the option that would cause special-use prefixes 174 reserved for IPv4/IPv6 translation to "pollute" the minimum possible 175 amount of unallocated IPv6 address space. 177 Finally, 64:ff9b:1::/48 also has the advantage that its textual 178 representation is considerably shorter than 64:ff9a:ffff:ffff::/48. 179 While this might seem insignificant, the preference human network 180 operators have for addresses that are simple to type should not be 181 underestimated. 183 After weighing the above pros and cons, 64:ff9b:1::/48 was chosen. 185 5. Deployment Considerations 187 64:ff9b:1::/48 is intended as a technology-agnostic and generic 188 reservation. A network operator may freely use it in combination 189 with any kind of IPv4/IPv6 translation mechanism deployed within his 190 network. 192 By default, IPv6 nodes and applications must not treat IPv6 addresses 193 within 64:ff9b:1::/48 different from other globally scoped IPv6 194 addresses. In particular, they must not make any assumptions 195 regarding the syntax or properties of those addresses (e.g., the 196 existence and location of embedded IPv4 addresses), or the type of 197 associated translation mechanism (e.g., whether it is stateful or 198 stateless). 200 64:ff9b:1::/48 or any other more-specific prefix SHOULD NOT be 201 advertised in inter-domain routing, except by explicit agreement 202 between all involved parties. Such prefixes MUST NOT be advertised 203 to the default-free zone. 205 When 64:ff9b:1::/48 or a more-specific prefix is used with the 206 [RFC6052] algorithm, it is considered to be a Network-Specific 207 Prefix. 209 Operators tempted to use the covering aggregate prefix 64:ff9b::/47 210 to refer to all special-use prefixes currently reserved for IPv4/IPv6 211 translation should be warned that this aggregate includes a range of 212 unallocated addresses (Section 4.2) that the IETF could potentially 213 reserve in the future for entirely different purposes. 215 6. Checksum Neutrality 217 Use of 64:ff9b:1::/48 does not in itself guarantee checksum 218 neutrality, as many of the IPv4/IPv6 translation algorithms it can be 219 used with are fundamentally incompatible with checksum-neutral 220 address translations. 222 The Stateless IP/ICMP Translation algorithm [RFC7915] is one well- 223 known algorithm that can operate in a checksum-neutral manner, when 224 using the [RFC6052] algorithm for all of its address translations. 225 However, in order to attain checksum neutrality is imperative that 226 the translation prefix is chosen carefully. Specifically, in order 227 for a 96-bit [RFC6052] prefix to be checksum neutral, all the six 228 16-bit words in the prefix must add up to a multiple of 0xffff. 230 The following non-exhaustive list contains examples of translation 231 prefixes that are checksum neutral when used with the [RFC7915] and 232 [RFC6052] algorithms: 234 o 64:ff9b:1:fffe::/96 236 o 64:ff9b:1:fffd:1::/96 238 o 64:ff9b:1:fffc:2::/96 240 o 64:ff9b:1:abcd:0:5431::/96 241 Section 4.1 of [RFC6052] contains further discussion about IPv4/IPv6 242 translation and checksum neutrality. 244 7. IANA Considerations 246 The IANA is requested to add the following entry to the IPv6 Special- 247 Purpose Address Registry: 249 +----------------------+---------------------+ 250 | Attribute | Value | 251 +----------------------+---------------------+ 252 | Address Block | 64:ff9b:1::/48 | 253 | Name | IPv4-IPv6 Translat. | 254 | RFC | (TBD) | 255 | Allocation Date | (TBD) | 256 | Termination Date | N/A | 257 | Source | True | 258 | Destination | True | 259 | Forwardable | True | 260 | Global | False | 261 | Reserved-by-Protocol | False | 262 +----------------------+---------------------+ 264 The IANA is furthermore requested to add the following footnote to 265 the 0000::/8 entry of the Internet Protocol Version 6 Address Space 266 registry: 268 64:ff9b:1::/48 reserved for Local-use IPv4/IPv6 Translation [TBD] 270 8. Security Considerations 272 The reservation of 64:ff9b:1::/48 is not known to cause any new 273 security considerations beyond those documented in Section 5 of 274 [RFC6052]. 276 9. References 278 9.1. Normative References 280 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 281 Requirement Levels", BCP 14, RFC 2119, 282 DOI 10.17487/RFC2119, March 1997, 283 . 285 [RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X. 286 Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052, 287 DOI 10.17487/RFC6052, October 2010, 288 . 290 9.2. Informative References 292 [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., 293 and E. Lear, "Address Allocation for Private Internets", 294 BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, 295 . 297 [RFC7915] Bao, C., Li, X., Baker, F., Anderson, T., and F. Gont, 298 "IP/ICMP Translation Algorithm", RFC 7915, 299 DOI 10.17487/RFC7915, June 2016, 300 . 302 Appendix A. Acknowledgements 304 The author would like to thank Fred Baker, Mohamed Boucadair, Brian E 305 Carpenter, Pier Carlo Chiodi, David Farmer, Holger Metschulat and 306 David Schinazi for 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