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Found 'MUST not' in this paragraph: Just as in [2], if a prefix is advertised with a metric larger than MAX_V6_PATH_METRIC (0xFE000000), this prefix MUST not be considered during the normal SPF computation. This will allow advertisement of a prefix for purposes other than building the normal IPv6 routing table. -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. 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 (8 January 2003) is 7772 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) -- Possible downref: Non-RFC (?) normative reference: ref. '0' -- Possible downref: Non-RFC (?) normative reference: ref. '2' Summary: 5 errors (**), 0 flaws (~~), 4 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Internet Engineering Task Force Christian E. Hopps 2 INTERNET-DRAFT Allegro Networks 3 Expires June 2003 8 January 2003 5 Routing IPv6 with IS-IS 6 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/1id-abstracts.html 26 The list of Internet-Draft Shadow Directories can be accessed at 27 http://www.ietf.org/shadow.html 29 Copyright Notice 31 Copyright (C) The Internet Society 2003. All Rights Reserved. 33 Draft Routing IPv6 with IS-IS January 2003 35 Abstract 37 This draft specifies a method for exchanging IPv6 routing information 38 using the IS-IS routing protocol. The described method utilizes 2 39 new TLVs, a reachability TLV and an interface address TLV to 40 distribute the necessary IPv6 information throughout a routing 41 domain. Using this method one can route IPv6 along with IPv4 and OSI 42 using a single intra-domain routing protocol. 44 1. Terms 46 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 47 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 48 document are to be interpreted as described in RFC 2119. 50 2. Overview 52 IS-IS [0] is an extendible intra-domain routing protocol. Each 53 router in the routing domain issues an LSP that contains information 54 pertaining to that router. The LSP contains typed variable length 55 data often referred to as TLVs (type-length-values). We extend the 56 protocol with 2 new TLVs to carry information required to perform 57 IPv6 routing. 59 In [1] a method is described to route both OSI and IPv4. We utilize 60 this same method with some minor changes to allow for IPv6. To do so 61 we must define 2 new TLVs, namely "IPv6 Reachability" and "IPv6 62 Interface Address" and a new IPv6 protocol identifier. In our new 63 TLVs we utilize the extended metrics and up/down semantics of [2]. 65 3. IPv6 Reachability TLV 67 The "IPv6 Reachability" TLV is TLV type 236 (0xEC). 69 [1] defines 2 Reachability TLVs, "IP Internal Reachability 70 Information" and "IP External Reachability Information". We provide 71 the equivalent IPv6 data with the "IPv6 Reachability" TLV and an 72 "external" bit. 74 The "IPv6 Reachability" TLV describes network reachability through 75 the specification of a routing prefix, metric information, a bit to 76 indicate if the prefix is being advertised down from a higher level, 78 Draft Routing IPv6 with IS-IS January 2003 80 a bit to indicate if the prefix is being distributed from another 81 routing protocol and OPTIONALLY the existence of sub-TLVs to allow 82 for later extension. This data is represented by the following 83 structure: 85 0 1 2 3 86 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 87 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 88 | Type = 236 | Length | Metric .. | 89 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 90 | .. Metric |U|X|S| Reserve | Prefix Len | 91 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 92 | Prefix ... 93 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 94 |Sub-TLV Len(*) | Sub-TLVs(*) ... 95 * - if present 97 U - up/down bit 98 X - external original bit 99 S - subtlv present bit 101 This structure MAY appear any number of times (including none) within 102 the TLV. 104 As is described in [2], "the up/down bit is set to 0 when a prefix is 105 first injected into IS-IS. If a prefix is redistributed from a 106 higher level to a lower level (e.g., level two to level one), the bit 107 SHALL be set to 1 to indicate that the prefix has travelled down the 108 hierarchy. If a prefix is redistributed from an area to another area 109 at the same level then the up/down bit SHALL be set to 1." 111 If the prefix was distributed into IS-IS from another routing 112 protocol the external bit SHALL be set to 1. This information is 113 useful when distributing prefixes from IS-IS to other protocols. 115 If the sub-TLV bit is set to 0 then the octets of sub-TLVs are not 116 present. Otherwise the bit is 1 and the octet following the prefix 117 will contain the length of the sub-TLV portion of the structure. 119 The prefix is "packed" in the data structure. That is, only the 120 required number of octets of prefix are present. This number can be 121 computed from the prefix length octet as follows: 123 prefix octets = integer of ((prefix length + 7) / 8) 125 Draft Routing IPv6 with IS-IS January 2003 127 Just as in [2], if a prefix is advertised with a metric larger than 128 MAX_V6_PATH_METRIC (0xFE000000), this prefix MUST not be considered 129 during the normal SPF computation. This will allow advertisement of 130 a prefix for purposes other than building the normal IPv6 routing 131 table. 133 If sub-TLVs are present they have the same form as normal TLVs as 134 shown below. 136 0 1 2 3 137 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 1 138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 139 | Type | Length | Value(*) .. 140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 141 * - if present 143 Length indicates how many octets of value are present and can be 0. 145 4. IPv6 Interface Address TLV 147 The "IPv6 Interface Address" TLV is TLV type 232 (0xE8). 149 This TLV maps directly to [1]'s "IP Interface Address" TLV. We 150 necessarily modify the contents to be 0-15 16 octet IPv6 interface 151 addresses instead of 0-63 4 octet IPv4 interface address. 153 0 1 2 3 154 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 1 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | Type = 232 | Length | Interface Address 1(*) .. | 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | .. Interface Address 1(*) .. | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | .. Interface Address 1(*) .. | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 | .. Interface Address 1(*) .. | 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | Interface Address 1(*) .. | Interface Address 2(*) .. 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 * - if present 168 We further restrict the semantics of this TLV depending on where it 169 is advertised. For Hello PDUs the "Interfaces Address" TLV MUST 170 contain only the link-local IPv6 addresses assigned to the interface 172 Draft Routing IPv6 with IS-IS January 2003 174 which is sending the Hello. For LSPs the "Interfaces Address" TLVs 175 MUST contain only the non-link-local IPv6 addresses assigned to the 176 IS. 178 5. IPv6 NLPID 180 The value of the IPv6 NLPID is 142 (0x8E). 182 As with [1] and IPv4, if the IS supports IPv6 routing using IS-IS, it 183 MUST advertise this in the "NLPID" TLV by adding the IPv6 NLPID. 185 6. Operation 187 We utilize the same changes to [1] as made in [2] for the processing 188 of prefix information. These changes are both related to the SPF 189 calculation. 191 Since the metric space has been extended we need to redefine the 192 MAX_PATH_METRIC (1023) from the original specification in [1]. This 193 new value MAX_V6_PATH_METRIC is the same as in [2] (0xFE000000). If 194 during the SPF a path metric would exceed MAX_V6_PATH_METRIC it SHALL 195 be considered to be MAX_V6_PATH_METRIC. 197 The order of preference between paths for a given prefix MUST be 198 modified to consider the up/down bit. The new order of preference is 199 as follows (from best to worst). 201 1. Level 1 up prefix 202 2. Level 2 up prefix 203 3. Level 2 down prefix 204 4. Level 1 down prefix 206 If multiple paths have the same best preference then selection occurs 207 based on metric. Any remaining multiple paths SHOULD be considered 208 for equal-cost multi-path routing if the router supports this, otherwise 209 the router can select any one of the multiple paths. 211 7. Security Considerations 213 This document raises no new security considerations. 215 Draft Routing IPv6 with IS-IS January 2003 217 8. References 219 [0] "Intermediate System to Intermediate System Intra-Domain Routeing 220 Exchange Protocol for use in Conjunction with the Protocol for 221 Providing the Connectionless-mode Network Service (ISO 8473)", ISO 222 10589, 1992. 224 [1] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual 225 Environments", RFC 1195, December 1990. 227 [2] Smit, H., and T. Li, "IS-IS extensions for Traffic Engineering", 228 Work in Progress, August 2001. 230 9. Author's Address 232 Christian E. Hopps 233 Allagro Networks 234 6399 San Ignacio Ave. 235 San Jose, CA 95119 236 U.S.A. 237 Phone: +1 408 281 5500 238 Email: chopps@allegronetworks.com 240 10. Full Copyright Statement 242 Copyright (C) The Internet Society 2003. All Rights Reserved. 244 This document and translations of it may be copied and furnished to 245 others, and derivative works that comment on or otherwise explain it 246 or assist in its implementation may be prepared, copied, published 247 and distributed, in whole or in part, without restriction of any 248 kind, provided that the above copyright notice and this paragraph are 249 included on all such copies and derivative works. However, this 250 document itself may not be modified in any way, such as by removing 251 the copyright notice or references to the Internet Society or other 252 Internet organizations, except as needed for the purpose of 253 developing Internet standards in which case the procedures for 254 copyrights defined in the Internet Standards process must be 255 followed, or as required to translate it into languages other than 256 English. 258 The limited permissions granted above are perpetual and will not be 259 revoked by the Internet Society or its successors or assigns. 261 Draft Routing IPv6 with IS-IS January 2003 263 This document and the information contained herein is provided on an 264 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 265 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 266 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 267 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 268 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.