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Hinden 5 Intended status: Standards Track Check Point 6 Expires: August 20, 2012 February 17, 2012 8 Representing IPv6 Zone Identifiers in Uniform Resource Identifiers 9 draft-ietf-6man-uri-zoneid-00 11 Abstract 13 This document describes how the Zone Identifier of an IPv6 scoped 14 address can be represented in a Uniform Resource Identifier that 15 includes a literal IPv6 address. It updates RFC 3986 and RFC 4007. 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 August 20, 2012. 34 Copyright Notice 36 Copyright (c) 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 52 2. Specification . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 54 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 55 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 56 6. Change log [RFC Editor: Please remove] . . . . . . . . . . . . 5 57 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 58 7.1. Normative References . . . . . . . . . . . . . . . . . . . 6 59 7.2. Informative References . . . . . . . . . . . . . . . . . . 6 60 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 62 1. Introduction 64 [RFC3986] defined how a literal IPv6 address can be represented in 65 the "host" part of a Uniform Resource Identifier (URI). 66 Subsequently, [RFC4007] extended the text representation of limited- 67 scope IPv6 addresses such that a zone identifier may be concatenated 68 to an address, for purposes described in that RFC. Zone identifiers 69 are especially useful in contexts where literal addresses are 70 typically used, for example during fault diagnosis, when it may be 71 essential to specify which interface is used for sending to a link 72 local address. It should be noted that zone identifiers have purely 73 local meaning within the host where they are defined, and they are 74 completely meaningless for any other host. 76 RFC 4007 does not specify how zone identifiers are to be represented 77 in URIs. Practical experience has shown that this feature is useful, 78 in particular when using a web browser for debugging with link local 79 addresses, but as it is undefined, it is not implemented consistently 80 in URI parsers or in browsers. 82 This document updates [RFC3986] by adding syntax to allow a zone 83 identifier to be included in a literal IPv6 address. It also 84 clarifies some statements in [RFC4007]. 86 It should be noted that in other contexts than a user interface, a 87 zone identifier is mapped into a numeric zone index or interface 88 number. The MIB textual convention [RFC4001] and the socket 89 interface [RFC3493] define this as a 32 bit unsigned integer. The 90 mapping between the human-readable zone identifier string and the 91 numeric value is a host-specific function that varies between 92 operating systems. The present document is concerned only with the 93 human-readable string. 95 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 96 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 97 document are to be interpreted as described in [RFC2119]. 99 2. Specification 101 According to RFC 4007, a zone identifier is attached to the textual 102 representation of an IPv6 address by concatenating "%" followed by 103 , where is a string identifying the zone of the 104 address. However, RFC 4007 gives no precise definition of the 105 character set allowed in . There are no rules or de facto 106 standards for this. For example, the first Ethernet interface in a 107 host might be called %0, %1, %en1, %eth0, or whatever the implementer 108 happened to choose. 110 In a URI, a literal IPv6 address is always embedded between "[" and 111 "]". This document specifies that may contain any ASCII 112 character classified in RFC 3986 as "unreserved", which conveniently 113 excludes "]" in order to simplify parsing. 115 There is an additional complication in that "%" is always treated as 116 an escape character in a URI, and according to RFC 3986 it MUST 117 therefore itself be escaped in a URI, in the form "%25". Thus, the 118 scoped address fe80::a%en1 would appear in a produced URI as 119 http://[fe80::a%25en1]. 121 If an operating system uses any other characters in zone or interface 122 identifiers that are not in the "unreserved" character set, they too 123 MUST be escaped with a "%" sign according to RFC 3986. 125 In RFC 3986, the IPv6 literal format is formally defined in ABNF 126 [RFC5234] by the following rule: 128 IP-literal = "[" ( IPv6address / IPvFuture ) "]" 130 To provide support for a zone identifier, the existing syntax of 131 IPv6address is retained, and a zone identifier may be added 132 optionally to any literal address. This allows flexibility for 133 unknown future uses. The rule quoted above from RFC 3986 is replaced 134 by three rules: 136 IP-literal = "[" ( IPv6addrz / IPvFuture ) "]" 138 ZoneID = 1*( unreserved / pct-encoded ) 140 IPv6addrz = IPv6address [ "%" ZoneID ] 142 The rules in [RFC5952] SHOULD be applied in producing URIs. The user 143 MUST replace "%" by "%25" when manually constructing such a URI, and 144 similarly for any other characters that are not in the "unreserved" 145 character set of RFC 3986. The option to include such characters 146 SHOULD NOT be used, but is included for the case of operating systems 147 that allow such characters in interface names. 149 The 6man WG discussed and rejected an alternative in which the 150 existing syntax of IPv6address would be extended by an option to add 151 the ZoneID only for the case of link-local addresses. It was felt 152 that the present solution offers more flexibility for future uses and 153 is more straightforward to implement. 155 RFC 4007 offers guidance on how the ZoneID affects interface/address 156 selection inside the IPv6 stack. Note that the behaviour of an IPv6 157 stack if passed a non-zero zone index for an address other than link- 158 local is undefined. 160 3. Security Considerations 162 The security considerations of [RFC3986] and [RFC4007] apply. In 163 particular, this URI format creates a specific pathway by which a 164 deceitful zone index might be communicated, as mentioned in the final 165 security consideration of RFC 4007. It is emphasised that the format 166 is intended only for debugging purposes, but of course this intention 167 does not prevent misuse. 169 To limit this risk, implementations SHOULD NOT allow use of this 170 format except for well-defined usages such as sending to link local 171 addresses under prefix fe80::/10. 173 An HTTP server or proxy MUST ignore any ZoneID attached to an 174 incoming URI, as it only has local significance at the sending host. 176 4. IANA Considerations 178 This document requests no action by IANA. 180 5. Acknowledgements 182 The lack of this format was pointed out by Kerry Lynn. Valuable 183 comments and contributions were made by Karl Auer, Brian Haberman, 184 Tatuya Jinmei, Tom Petch, Tomoyuki Sahara, and Juergen Schoenwaelder. 186 This document was produced using the xml2rfc tool [RFC2629]. 188 6. Change log [RFC Editor: Please remove] 190 draft-ietf-6man-uri-zoneid-00: adopted by WG, fixed syntax to allow 191 for % encoded characters, 2012-02-17. 193 draft-carpenter-v6ops-label-balance-01: chose Option 2, removed 15 194 character limit, added explanation of ID/number mapping and other 195 clarifications, 2012-02-08. 197 draft-carpenter-v6ops-label-balance-00: original version, 2011-12-07. 199 7. References 200 7.1. Normative References 202 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 203 Requirement Levels", BCP 14, RFC 2119, March 1997. 205 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 206 Resource Identifier (URI): Generic Syntax", STD 66, 207 RFC 3986, January 2005. 209 [RFC4007] Deering, S., Haberman, B., Jinmei, T., Nordmark, E., and 210 B. Zill, "IPv6 Scoped Address Architecture", RFC 4007, 211 March 2005. 213 [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax 214 Specifications: ABNF", STD 68, RFC 5234, January 2008. 216 [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 217 Address Text Representation", RFC 5952, August 2010. 219 7.2. Informative References 221 [RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629, 222 June 1999. 224 [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. 225 Stevens, "Basic Socket Interface Extensions for IPv6", 226 RFC 3493, February 2003. 228 [RFC4001] Daniele, M., Haberman, B., Routhier, S., and J. 229 Schoenwaelder, "Textual Conventions for Internet Network 230 Addresses", RFC 4001, February 2005. 232 Authors' Addresses 234 Brian Carpenter 235 Department of Computer Science 236 University of Auckland 237 PB 92019 238 Auckland, 1142 239 New Zealand 241 Email: brian.e.carpenter@gmail.com 242 Robert M. Hinden 243 Check Point Software Technologies, Inc. 244 800 Bridge Parkway 245 Redwood City, CA 94065 246 US 248 Email: bob.hinden@gmail.com