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If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (14 Mar 2003) is 7713 days in the past. 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) No issues found here. Summary: 2 errors (**), 0 flaws (~~), 10 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group A.K. Vijayabhaskar 2 Internet-Draft Hewlett-Packard 3 Expires: Sep 14, 2003 14 Mar 2003 5 Client Preferred Prefix option for DHCPv6 6 draft-ietf-dhc-dhcpv6-opt-cliprefprefix-01.txt 8 Status of this Memo 10 This document is an Internet-Draft and is in full conformance with 11 all provisions of Section 10 of RFC2026. 13 Internet-Drafts are working documents of the Internet Engineering 14 Task Force (IETF), its areas, and its working groups. Note that 15 other groups may also distribute working documents as Internet- 16 Drafts. 18 Internet-Drafts are draft documents valid for a maximum of six months 19 and may be updated, replaced, or obsoleted by other documents at any 20 time. It is inappropriate to use Internet-Drafts as reference 21 material or to cite them other than as "work in progress." 23 The list of current Internet-Drafts can be accessed at 24 http://www.ietf.org/ietf/1id-abstracts.txt. 26 The list of Internet-Draft Shadow Directories can be accessed at 27 http://www.ietf.org/shadow.html. 29 This Internet-Draft will expire on September 14, 2003. 31 Copyright Notice 33 Copyright (C) The Internet Society (2003). All Rights Reserved. 35 Abstract 37 This document describes the Client Preferred Prefix option by which 38 the client can specify its preferred prefixes on which the addresses 39 need to be allocated by the server. 41 1. Introduction 43 Scenario 1: The client's link has multiple prefixes of different 44 scopes and the administrator policy on the server insists that the 45 addresses need to be allocated on site-local prefixes only. The 46 client will not be able to communicate with a node that belongs to a 47 different site, as the server allocates only site-local addresses in 48 IAs. 50 Scenario 2: The client's link has two prefixes: site-local and global. 51 The administrator policy insists that addresses need to be allocated 52 on both the prefixes. All the nodes on a link will not communicate 53 with external sites and thus all of them do not require global 54 addresses. However, the server allocates addresses on both the 55 prefixes. So, the client needs to send the release message to release 56 the unwanted addresses, which requires extra transactions. 58 Scenario 3: The node has used the stateless autoconf and learned 59 about prefixes. Say, the link has two prefixes 3ffe::/64 and 60 3fff::/64 and the link has been subnetted to two sets with these 61 prefixes. Now, suddenly the RAs say to use stateful autoconf. It 62 depends up on the dhcpv6 configuration whether the node will get both 63 the prefixes or not. It will be worser if the node using 3ffe::/64 64 has to renumber to 3fff::/64 unnecessarily, though both the prefixes 65 are valid in the link. 67 Scenario 4: In a highly secured environment where there is only a 68 known IPv6 prefix by specific entities provided the knowledge of that 69 prefix out of band not over a network. The entity will request this 70 prefix as a DHCPv6 client and will provide secret security parameter 71 to the DHCPv6 server. The server then provides a complete address for 72 that prefix. The entity client now can use that address for 73 communications with nodes that accept no other prefix on the network. 74 The applications for this are special operations for entities like 75 the Military, Law Enforcement, Fire Departments, and Doctors. 77 To overcome the problems described in the above Scenarios, the client 78 can specify its preferred prefixes to the server using Client 79 Preferred Prefix option. 81 2. Requirements 83 The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, 84 SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this 85 document, are to be interpreted as described in RFC 2119 [2] 87 3. Terminology 89 This document uses terminology specific to IPv6 and DHCPv6 as defined 90 in section "Terminology" of the DHCP specification. 92 4. Client Preferred Prefix option 94 Client Preferred Prefix option is used by the client to specify its 95 preferred prefixes to the server. 97 The format of the Client Preferred Prefix option is as shown below: 99 0 1 2 3 100 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 101 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 102 | OPTION_CLIENT_PREF_PREFIX | option-len | 103 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 104 | prefix-len | | 105 +-+-+-+-+-+-+-+-+-+ | 106 | | 107 | subnet prefix (n bytes) | 108 | | 109 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 110 | prefix-len | | 111 +-+-+-+-+-+-+-+-+-+ | 112 | | 113 | subnet prefix (n bytes) | 114 | | 115 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 116 | ... | 117 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 118 . . 119 . client-pref-prefix-options . 120 . . 121 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 123 option-code: OPTION_CLIENT_PREF_PREFIX (tbd) 125 option-len: total length of the prefix-len and subnet prefix lists 126 and its encapsulated options. 128 prefix-len: prefix length of the subnet address. 130 subnet prefix: 'n' bytes of subnet prefix, where 'n' is minimum 131 number of bytes required to refer 'prefix-len' bits 132 of the prefix. 134 client-pref-prefix-options: options associated with Client 135 Preferred Prefix option. 137 5. Server Behavior 139 If the server policy doesn't support client preferred prefix option, 140 then it can either send reply with OptionUnsupported in the 141 encapsulated error code option in client preferred prefix option or 142 allocate addresses based on its original policy. The server behavior 143 SHOULD be configurable by the administrator. 145 If the server policy supports client preferred prefix option and if 146 this option contains one or more prefixes which are not valid for the 147 client's link, then, the server MUST send the reply with error code 148 NotOnLink. 150 If the server policy supports client preferred prefix option and all 151 the prefixes in this option are valid for the client's link, then the 152 server MUST allocate addresses only on the prefixes specified in 153 client preferred prefix option encapsulated in the IAs. 155 6. Client Behavior 157 If the client has received OptionUnsupported error, it can either 158 choose the next server to send request, till the server list gets 159 exhausted or it can start the configuration exchange as specified in 160 Section 18.1.1 of [1] without the client preferred prefix option. 162 If the server list has exhausted then, it MUST start the configuration 163 exchange as specified in Section 18.1.1 of [1] without the client 164 preferred prefix option. 166 If the client has received the addresses with the prefixes that were 167 not specified in client preferred prefix option, it can release the 168 unwanted addresses. 170 7. Appearance of these options 172 Client Preferred Prefix option MUST occur only in Request and Reply 173 messages. This option MUST occur in Reply messages only if it 174 encapsulates the Error code option. 176 Client Preferred Prefix option MUST occur only as an encapsulated 177 option in the IA or IA_TA option. 179 Client Preferred Prefix option MUST only have Error code option as the 180 encapsulated option. 182 8. Security Considerations 184 Since, this option can occur only in IA or IA_TA option, all the 185 IA-relevant security considerations are applicable to this option too. 187 To avoid attacks through this option, the DHCP client SHOULD use 188 authenticated DHCP (see section "Authentication of DHCP messages" 189 in the DHCPv6 specification [1]). 191 9. IANA Considerations 193 IANA is requested to assign an option code to this option from the 194 option-code space defined in section "DHCPv6 Options" of the DHCPv6 195 specification [1]. 197 10. Normative Reference 199 [1] Bound, J., Carney, M., Perkins, C., Lemon, T., Volz, B. and R. 200 Droms (ed.), "Dynamic Host Configuration Protocol for IPv6 201 (DHCPv6)", draft-ietf-dhc-dhcpv6-28 (work in progress), November 202 2002. 204 11. Informative Reference 206 [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement 207 Levels", BCP 14, RFC 2119, March 1997. 209 Author's Address 211 Vijayabhaskar A K 212 Hewlett-Packard ESD-I 213 29, Cunningham Road 214 Bangalore - 560052 215 India 217 Phone: +91-80-2053085 218 E-Mail: vijayak@india.hp.com 220 Full Copyright Statement 222 Copyright (C) The Internet Society (2003). All Rights Reserved. 224 This document and translations of it may be copied and furnished to 225 others, and derivative works that comment on or otherwise explain it 226 or assist in its implementation may be prepared, copied, published 227 and distributed, in whole or in part, without restriction of any 228 kind, provided that the above copyright notice and this paragraph are 229 included on all such copies and derivative works. However, this 230 document itself may not be modified in any way, such as by removing 231 the copyright notice or references to the Internet Society or other 232 Internet organizations, except as needed for the purpose of 233 developing Internet standards in which case the procedures for 234 copyrights defined in the Internet Standards process must be 235 followed, or as required to translate it into languages other than 236 English. 238 The limited permissions granted above are perpetual and will not be 239 revoked by the Internet Society or its successors or assigns. 241 This document and the information contained herein is provided on an 242 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 243 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 244 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 245 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 246 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 248 Acknowledgement 250 Funding for the RFC Editor function is currently provided by the 251 Internet Society. Thanks to Jim Bound for his thorough review 252 of the document.