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'I-D.ietf-teas-native-ip-scenarios') == Outdated reference: A later version (-13) exists of draft-ietf-teas-pcecc-use-cases-01 ** Downref: Normative reference to an Informational draft: draft-ietf-teas-pcecc-use-cases (ref. 'I-D.ietf-teas-pcecc-use-cases') ** Obsolete normative reference: RFC 7752 (Obsoleted by RFC 9552) == Outdated reference: A later version (-02) exists of draft-wang-idr-bgpls-inter-as-topology-ext-00 Summary: 4 errors (**), 0 flaws (~~), 9 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 LSR Working Group A. Wang 3 Internet-Draft China Telecom 4 Intended status: Standards Track June 28, 2018 5 Expires: December 30, 2018 7 OSPF Extend for Inter-Area Topology Retrieval 8 draft-wang-lsr-ospf-inter-area-topology-ext-00 10 Abstract 12 This document describes method to transfer the source router id of 13 inter-area prefixes for OSPFv2 [RFC2328] and OSPFv3 [RFC5340], which 14 is needed in topology retrieval processing for inter-area scenario. 16 Status of This Memo 18 This Internet-Draft is submitted in full conformance with the 19 provisions of BCP 78 and BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF). Note that other groups may also distribute 23 working documents as Internet-Drafts. The list of current Internet- 24 Drafts is at https://datatracker.ietf.org/drafts/current/. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 This Internet-Draft will expire on December 30, 2018. 33 Copyright Notice 35 Copyright (c) 2018 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents 40 (https://trustee.ietf.org/license-info) in effect on the date of 41 publication of this document. Please review these documents 42 carefully, as they describe your rights and restrictions with respect 43 to this document. Code Components extracted from this document must 44 include Simplified BSD License text as described in Section 4.e of 45 the Trust Legal Provisions and are provided without warranty as 46 described in the Simplified BSD License. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 51 2. Conventions used in this document . . . . . . . . . . . . . . 2 52 3. Inter-Area Topology Retrieval Scenario . . . . . . . . . . . 3 53 3.1. OSPFv2 Extend Solution (IPv4 Source Router ID) . . . . . 4 54 3.2. OSPFv3 Extend Solution (IPv6 Source Router ID) . . . . . 5 55 3.3. Prefix Source Router ID sub TLV . . . . . . . . . . . . . 7 56 3.4. Extend LSA generate process . . . . . . . . . . . . . . . 8 57 3.5. Inter-Area Topology Retrieval Process . . . . . . . . . . 8 58 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 59 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 60 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 61 6.1. Normative References . . . . . . . . . . . . . . . . . . 9 62 6.2. Informative References . . . . . . . . . . . . . . . . . 10 63 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10 65 1. Introduction 67 BGP-LS [RFC7752] describes the methodology that using BGP protocol to 68 transfer the Link-State information. Such method can enable SDN 69 controller to collect the underlay network topology automatically. 71 But if the underlay network is divided into multi area and running 72 OSPF protocol, it is not easy for the SDN controller to rebuild the 73 multi-area topology, because normally the ABR that locates on the 74 boundary of different area will hide the detail topology information 75 in non-backbone area, and the router in backbone area that runs BGP- 76 LS protocol can only get and report the summary network information 77 in non-backbone area. 79 [RFC7794] introduces "IPv4/IPv6 Source Router IDs" TLV to label the 80 source of the prefixes redistributed from different Level, this TLV 81 can be used to reconstruct the detail overall topology within level 1 82 and level 2. Such solution can also be applied into network that run 83 OSPF protocol, but the related LSP message must be redefined. 85 This draft gives such solution for the OSPF v2 and OSPF v3 protocol. 87 2. Conventions used in this document 89 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 90 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 91 document are to be interpreted as described in [RFC2119] . 93 3. Inter-Area Topology Retrieval Scenario 95 Fig.1 illustrates the topology retrieval scenario when OSPF is 96 running in multi-area. R0-R4 are routers in backbone area, 97 S1-S4,T1-T4 are interal router in area 1 and area 2 respectively. R1 98 and R3 are border routers between area 0 and area 1; R2 and R4 are 99 border routers between area 0 and area 2. N1 is the network between 100 router S1 and S2, N2 is the network between router T1 and T2. 102 Normally, ABR router R1 or R3 will send the summary LSA(for OSPFv2) 103 or Inter-Area-Prefix-LSAs(for OSPFv3) for network N1. When R0 104 receives such LSA, it can only know network N1 locates behind R1, and 105 does not know where it is originated. When R0 reports the summary 106 LSA information via BGP-LS protocol, the IP SDN controller can't 107 certainly deduce the detail network topology within area 1. The 108 situation is same as that in Area 2. 110 +-----------------+ 111 |IP SDN Controller| 112 +--------+--------+ 113 | 114 |BGP-LS 115 | 116 +---------------------+------+--------+-----+--------------+ 117 | +--+ +--+ ++-+ ++-+ +-++ + -+ +--+| 118 | |S1+--------+S2+---+R1+---|R0+----+R2+---+T1+--------+T2|| 119 | +-++ N1 +-++ ++-+ +--+ +-++ ++++ N2 +-++| 120 | | | | | || | | 121 | | | | | || | | 122 | +-++ +-++ ++-+ +-++ ++++ +-++| 123 | |S4+--------+S3+---+R3+-----------+R4+---+T3+--------+T4|| 124 | +--+ +--+ ++-+ +-++ ++-+ +--+| 125 | | | | 126 | | | | 127 | Area 1 | Area 0 | Area 2 | 128 +---------------------+---------------+--------------------+ 130 Fig.1 OSPF Inter-Area Topology Retrieval Scenario 132 If R0 has some methods to know the originator of network N1 and 133 reports such information to IP SDN controller, then it is easy for 134 the controller to retrieval the detail topology in non-backbone area. 136 Because traditional OSPFv2/v3 packet is not in the TLV format, we 137 need to find some solutions to reuse or redefine the existing fields 138 in summary LSA (OSPFv2) and Inter-Area-Prefix-LSAs(for OSPFv3)to 139 transfer the additional information. The extend methods should not 140 conflict with the usage of existing semantics. 142 Section 3.1 and section 3.2 give the proposed solutions for OSPFv2 143 and OSPFv3 respectively. 145 3.1. OSPFv2 Extend Solution (IPv4 Source Router ID) 147 0 1 2 3 148 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 1 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 150 | LS age | Options | 3 or 4 | 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 | Link State ID | 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 154 | Advertising Router | 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | LS sequence number | 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | LS checksum | length | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 | Network Mask | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 | 0 | metric | 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 | TOS | TOS metric | 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 | ... | 168 Fig.2 Summary LSA Format 170 Fig.2 illustrates the format of summary LSA. There is one byte that 171 originately defined for the number of TOS types but in actually this 172 feature does not applied in real network or implemented in the main 173 stream router. 175 To transfer the additional information, this draft proposes to reuse/ 176 redefine this field. In order to prevent possible conflict, even it 177 is in very rare event, we can start the usage of this field from the 178 upper limit, for example, 0xFE. Then the proposed extend summary LSA 179 format is the followings: 181 0 1 2 3 182 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 1 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 184 | LS age | Options | 3 or 4 | 185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 186 | Link State ID | 187 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 188 | Advertising Router | 189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 190 | LS sequence number | 191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 192 | LS checksum | length | 193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 | Network Mask | 195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 196 | 0xFE | metric | 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | IPv4 Source Router ID | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | Area ID | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 Fig.3 Extended Summary LSA Format 205 That is to say, if the field of "Numbers of TOS" equal "0xFE", then 206 the "IPv4 Source Router ID"(4 bytes) of the inter-area network 207 reported in summary LSA and its associated area id(4 bytes) are 208 included in the field that follows the "metric" field. 210 3.2. OSPFv3 Extend Solution (IPv6 Source Router ID) 211 0 1 2 3 212 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 1 213 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 214 | LS Age |0|0|1| 3 | 215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 | Link State ID | 217 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 | Advertising Router | 219 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 220 | LS Sequence Number | 221 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 222 | LS Checksum | Length | 223 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 224 | 0 | Metric | 225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 | PrefixLength | PrefixOptions | 0 | 227 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 | Address Prefix | 229 | ... | 230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 232 Fig.4 Inter-Area-Prefix-LSA Format 234 For OSPFv3, this draft proposes the similar method, because the 235 semantic of the Inter-Area-Prefix-LSA format is almost same as the 236 summary LSA format. 238 0 1 2 3 239 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 1 240 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 241 | LS Age |0|0|1| 3 | 242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 243 | Link State ID | 244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 245 | Advertising Router | 246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 247 | LS Sequence Number | 248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 249 | LS Checksum | Length | 250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 251 | 0xFE | Metric | 252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 253 | Prefix Source Router ID | 254 | ... | 255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 | Area ID | 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 258 | PrefixLength | PrefixOptions | 0 | 259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 260 | Address Prefix | 261 | ... | 262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 263 Fig.5 Extended Inter-Area-Prefix-LSA Format 265 If the value of "Numbers of TOS" equal "0xFE", then the "IPv6 source 266 router ID" (16 bytes) and its corresponding area ID (4 bytes) 267 information are inserted in the "Inter-Area-Prefix-LSA" after the 268 field "Metric". After this, the normal Prefix information is 269 followed as shown in Fig.5 271 3.3. Prefix Source Router ID sub TLV 273 [RFC7684] and [RFC8362] define the TLV format extension for OSPFv2 274 and OSPFv3 respectively. These documents give the flexibility to add 275 new attributes for the prefixes and links. Based on these formats, 276 we can define new sub TLV to transfer the "Prefix Source Router ID", 277 as that defined in [RFC7794]. 279 The proposed "Prefix Source Router ID" format is the following: 281 For IPv4 network, it is the following: 283 o Pv4 Source Router ID Type: TBD 285 o Length: 4 286 o Value: IPv4 Router ID of the source of the advertisement 288 This sub TLV should be included in the "OSPFv2 Extended Prefix Opaque 289 LSA" that defined in [RFC7684] 291 For IPv6 network, it is the following: 293 o IPv6 Source Router ID Type: TBD 295 o Length: 16 297 o Value: IPv6 Router ID of the source of the advertisement 299 This sub TLV should be included in "E-Inter-Area-Prefix-LSA" that 300 defined in [RFC8362] 302 3.4. Extend LSA generate process 304 When ABR(for example R1 in Fig.1)receives the "Router LSA" 305 announcement in area 1, it should generate the corresponding extend 306 "Summary LSA" or "Inter-Area-Prefix-LSA" that includes the "Source 307 Router ID" of the network prefixes, which labels the corresponding 308 link and the "area ID" that the source router belongs to. 310 When R0 receives such extend LSA, it then strips this additional 311 information, put it into the corresponding part that in BGP-LS 312 protocol as described in[I-D.wang-idr-bgpls-inter-as-topology-ext] 313 and reports them to the IP SDN Controller. 315 3.5. Inter-Area Topology Retrieval Process 317 When IP SDN Controller receives this information, it should compare 318 the prefix NLRI that included in the BGP-LS packet. When it 319 encounters the same prefix but with different source router ID, it 320 should extract the corresponding area ID, rebuild the link between 321 these two different source router in non-backbone area. 323 Iterating the above process continuously, the IP SDN controller can 324 then retrieve the detail topology that span multi-area. 326 4. Security Considerations 328 TBD. 330 5. IANA Considerations 332 TBD. 334 6. References 336 6.1. Normative References 338 [I-D.ietf-pce-pcep-extension-native-ip] 339 Wang, A., Khasanov, B., Cheruathur, S., and C. Zhu, "PCEP 340 Extension for Native IP Network", draft-ietf-pce-pcep- 341 extension-native-ip-00 (work in progress), June 2018. 343 [I-D.ietf-teas-native-ip-scenarios] 344 Wang, A., Huang, X., Qou, C., Huang, L., and K. Mi, "CCDR 345 Scenario, Simulation and Suggestion", draft-ietf-teas- 346 native-ip-scenarios-00 (work in progress), February 2018. 348 [I-D.ietf-teas-pcecc-use-cases] 349 Zhao, Q., Li, Z., Khasanov, B., Ke, Z., Fang, L., Zhou, 350 C., Communications, T., and A. Rachitskiy, "The Use Cases 351 for Using PCE as the Central Controller(PCECC) of LSPs", 352 draft-ietf-teas-pcecc-use-cases-01 (work in progress), May 353 2017. 355 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 356 Requirement Levels", BCP 14, RFC 2119, 357 DOI 10.17487/RFC2119, March 1997, 358 . 360 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 361 DOI 10.17487/RFC2328, April 1998, 362 . 364 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 365 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 366 . 368 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 369 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 370 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 371 2015, . 373 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 374 S. Ray, "North-Bound Distribution of Link-State and 375 Traffic Engineering (TE) Information Using BGP", RFC 7752, 376 DOI 10.17487/RFC7752, March 2016, 377 . 379 [RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and 380 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 381 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, 382 March 2016, . 384 [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and 385 F. Baker, "OSPFv3 Link State Advertisement (LSA) 386 Extensibility", RFC 8362, DOI 10.17487/RFC8362, April 387 2018, . 389 6.2. Informative References 391 [I-D.wang-idr-bgpls-inter-as-topology-ext] 392 Wang, A., "BGP-LS extend for inter-AS topology retrieval", 393 draft-wang-idr-bgpls-inter-as-topology-ext-00 (work in 394 progress), March 2018. 396 Author's Address 398 Aijun Wang 399 China Telecom 400 Beiqijia Town, Changping District 401 Beijing, Beijing 102209 402 China 404 Email: wangaj.bri@chinatelecom.cn