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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Krishnan 3 Internet-Draft Ericsson 4 Intended status: Standards Track December 3, 2008 5 Expires: June 6, 2009 7 Reserved IPv6 Interface Identifiers 8 draft-ietf-6man-reserved-iids-03 10 Status of this Memo 12 By submitting this Internet-Draft, each author represents that any 13 applicable patent or other IPR claims of which he or she is aware 14 have been or will be disclosed, and any of which he or she becomes 15 aware will be disclosed, in accordance with Section 6 of BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on June 6, 2009. 35 Abstract 37 Interface Identifiers in IPv6 unicast addresses are used to identify 38 interfaces on a link. They are required to be unique within a 39 subnet. Several RFCs have specified interface identifiers or 40 identifier ranges that have a special meaning attached to them. An 41 IPv6 node autoconfiguring an interface identifier in these ranges 42 will encounter unexpected consequences. Since there is no 43 centralized repository for such reserved identifiers, this document 44 aims to create one. 46 Table of Contents 48 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 49 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 50 2.1. Applicability . . . . . . . . . . . . . . . . . . . . . . 4 51 3. Issues with reusing reserved Interface Identifiers . . . . . . 5 52 3.1. Possible solutions . . . . . . . . . . . . . . . . . . . . 5 53 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 54 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 55 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 56 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 57 7.1. Normative References . . . . . . . . . . . . . . . . . . . 9 58 7.2. Informative References . . . . . . . . . . . . . . . . . . 9 59 Appendix A. List of potentially affected RFCs . . . . . . . . . . 10 60 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11 61 Intellectual Property and Copyright Statements . . . . . . . . . . 12 63 1. Requirements notation 65 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 66 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 67 document are to be interpreted as described in [RFC2119]. 69 2. Introduction 71 An IPv6 unicast address is composed of two parts : A subnet prefix 72 and an interface identifier (IID) that identifies an unique interface 73 within the subnet prefix. The structure of an IPv6 unicast address 74 is depicted in the IPv6 Addressing Architecture [RFC4291] and is 75 replicated here for clarity. 77 | n bits | 128-n bits | 78 +-------------------------------+---------------------------------+ 79 | subnet prefix | interface ID | 80 +-------------------------------+---------------------------------+ 82 Figure 1: IPv6 Unicast Address Format 84 For all unicast addresses, except those that start with the binary 85 value 000, Interface IDs are required to be 64 bits long and to be 86 constructed in Modified EUI-64 format. Examples of mechanisms that 87 generate interface identifiers without an unique token include 88 Cryptographically Generated Addresses [RFC3972], Privacy Addresses 89 [RFC4941], Hash Based Addresses [HBA] etc. Non-unique interface 90 identifiers can also be allocated using managed address assignment 91 mechanisms like DHCPv6 [RFC3315]. 93 2.1. Applicability 95 This document applies only to interface identifiers that are formed 96 in the modified EUI-64 format as defined in Appendix A of [RFC4291]. 97 All other types of interface identifiers are out of scope. 99 3. Issues with reusing reserved Interface Identifiers 101 Let us assume a node comes up with an interface identifier that has 102 been reserved for use in some other capacity. e.g. An IPv6 node that 103 uses temporary IPv6 addresses [RFC4941] comes up with an IID of fdff: 104 ffff:ffff:fff . This node will receive requests from all nodes that 105 are requesting a service from a MobileIPv6 home agent since the above 106 mentioned interface identifier has been reserved in [RFC2526] to 107 serve as a MIPv6 home agents anycast address. At best this is an 108 annoyance to the node that came up with this address. In the worst 109 case scenario another node on the link would be denied service and 110 may not look for other methods of acquiring a home agent. Thus, such 111 reserved interface identifiers MUST NOT be used for autonomous auto- 112 configuration or for managed address configuration. 114 3.1. Possible solutions 116 There are two possible ways to go about avoiding usage of these 117 reserved interface identifiers. One of them would be to add 118 normative reference to each specification that reserves an interface 119 identifier. The other one would be to create an IANA registry for 120 such interface identifiers. There are two disadvantages to the 121 normative reference approach. Firstly, this approach does not scale 122 well. This is because the number of such specifications that need to 123 be updated is large. Secondly, the maturity level of the document 124 reserving the IID might be lower than the one prohibited from using 125 it. This will cause a downward reference problem. Therefore the 126 better solution is to create an IANA registry for this purpose. 128 4. IANA Considerations 130 This document requests the creation of an IANA registry for reserved 131 IPv6 Interface Identifiers. Initial values for the reserved IPv6 132 Interface Identifiers are given below. 134 +-----------------------------------------+-------------------------+ 135 | Interface Identifier Range | Description | 136 +-----------------------------------------+-------------------------+ 137 | 0000:0000:0000:0000 | Subnet-Router Anycast | 138 | | [RFC4291] | 139 | | | 140 | FDFF:FFFF:FFFF:FF80-FDFF:FFFF:FFFF:FFFF | Reserved Subnet Anycast | 141 | | Addresses[RFC2526] | 142 +-----------------------------------------+-------------------------+ 144 Table 1: Current Assignments 146 It is possible that implementations might predate a specific 147 assignment from this registry and hence not be cognizant of the 148 reserved nature of the interface identifier. Hence, future 149 assignments from this registry are discouraged. Future assignments, 150 if any, are to be made through Standards Action [RFC5226]. 151 Assignments consist of a single interface identifier or a range of 152 interface identifiers. 154 NOTE: Please note that the address :: (all zeros in the interface 155 identifier field) is used as the unspecified address and ::/0 is used 156 as a default route indicator, as specified in [RFC5156]. These uses 157 do not conflict with the reserved interface identifiers defined here, 158 since the reserved identifiers defined in this document are used for 159 avoiding conflicts with stateless address autoconfiguration that 160 utilizes a 64 bit prefix length. 162 5. Acknowledgements 164 The author would like to thank Alain Durand, Alex Petrescu, Bernie 165 Volz, Bob Hinden, Christian Huitema, Fred Templin, Jordi Palet 166 Martinez, Pekka Savola, Remi Denis-Courmount, Tim Enos, Alex 167 Petrescu, Ed Jankiewicz, Brian Carpenter, Alfred Hoenes, Jari Arkko, 168 Pasi Eronen, Tim Polk, Lars Eggert, Derek Atkins and Robert Sparks 169 for reviewing this document and suggesting changes. 171 6. Security Considerations 173 By utilizing one of the reserved interface identifiers, an IPv6 node 174 might receive requests that it is not authorized to receive. 175 Information that creates or updates a registration in this registry 176 needs to be authenticated and authorized by the IANA based on the 177 instructions set forth by [RFC5226]. 179 7. References 181 7.1. Normative References 183 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 184 Requirement Levels", BCP 14, RFC 2119, March 1997. 186 [RFC2526] Johnson, D. and S. Deering, "Reserved IPv6 Subnet Anycast 187 Addresses", RFC 2526, March 1999. 189 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 190 Architecture", RFC 4291, February 2006. 192 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 193 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 194 May 2008. 196 7.2. Informative References 198 [HBA] Bagnulo, M., "Hash Based Addresses (HBA)", 199 draft-ietf-shim6-hba-05 (work in progress), October 2006. 201 [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., 202 and M. Carney, "Dynamic Host Configuration Protocol for 203 IPv6 (DHCPv6)", RFC 3315, July 2003. 205 [RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)", 206 RFC 3972, March 2005. 208 [RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy 209 Extensions for Stateless Address Autoconfiguration in 210 IPv6", RFC 4941, September 2007. 212 [RFC5156] Blanchet, M., "Special-Use IPv6 Addresses", RFC 5156, 213 April 2008. 215 Appendix A. List of potentially affected RFCs 217 The following RFCs that generate interface identifiers need to be 218 updated if they wish to avoid conflicts with the reserved interface 219 identifier ranges. 221 o RFC2590 - Transmission of IPv6 Packets over Frame Relay Networks 223 o RFC3315 - Dynamic Host Configuration Protocol for IPv6 (DHCPv6) 225 o RFC3972 - Cryptographically Generated Addresses (CGA) 227 o RFC4489 - A Method for Generating Link-Scoped IPv6 Multicast 228 Addresses 230 o RFC4862 - IPv6 Stateless Address Autoconfiguration 232 o RFC4941 - Privacy Extensions for Stateless Address 233 Autoconfiguration in IPv6 235 o RFC5072 - IP Version 6 over PPP 237 o RFC4982 - Support for Multiple Hash Algorithms in CGAs 239 Author's Address 241 Suresh Krishnan 242 Ericsson 243 8400 Decarie Blvd. 244 Town of Mount Royal, QC 245 Canada 247 Phone: +1 514 345 7900 x42871 248 Email: suresh.krishnan@ericsson.com 250 Full Copyright Statement 252 Copyright (C) The IETF Trust (2008). 254 This document is subject to the rights, licenses and restrictions 255 contained in BCP 78, and except as set forth therein, the authors 256 retain all their rights. 258 This document and the information contained herein are provided on an 259 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 260 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 261 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 262 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 263 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 264 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 266 Intellectual Property 268 The IETF takes no position regarding the validity or scope of any 269 Intellectual Property Rights or other rights that might be claimed to 270 pertain to the implementation or use of the technology described in 271 this document or the extent to which any license under such rights 272 might or might not be available; nor does it represent that it has 273 made any independent effort to identify any such rights. 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