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Summary: 4 errors (**), 0 flaws (~~), 11 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 TEAS Working Group A.Wang 2 Internet Draft China Telecom 4 Intended status: Standard Track March 5, 2018 5 Expires: September 4, 2018 7 BGP-LS extend for inter-AS topology retrieval 8 draft-wang-idr-bgpls-inter-as-topology-ext-00.txt 10 Status of this Memo 12 This Internet-Draft is submitted in full conformance with the 13 provisions of BCP 78 and BCP 79. 15 Internet-Drafts are working documents of the Internet Engineering 16 Task Force (IETF). Note that other groups may also distribute 17 working documents as Internet-Drafts. The list of current Internet- 18 Drafts is at https://datatracker.ietf.org/drafts/current/. 20 Internet-Drafts are draft documents valid for a maximum of six 21 months and may be updated, replaced, or obsoleted by other documents 22 at any time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as "work in progress." 25 This Internet-Draft will expire on August 31, 2018. 27 Copyright Notice 29 Copyright (c) 2018 IETF Trust and the persons identified as the 30 document authors. All rights reserved. 32 This document is subject to BCP 78 and the IETF Trust's Legal 33 Provisions Relating to IETF Documents 34 (http://trustee.ietf.org/license-info) in effect on the date of 35 publication of this document. Please review these documents 36 carefully, as they describe your rights and restrictions with 37 respect to this document. 39 Abstract 41 This document describes new TLVs extended for BGP-LS to transfer the 42 originator of redistributed routes and other inter-AS TE related 43 TLVs to let the SDN controller to retrieve the network topology 44 automatically under the multi-domain environments. 46 This extension can expand the usage of BGP-LS protocol to multi- 47 domain; enable the network operator to collect the connection 48 relationship between different domains and then calculate the 49 overall network topology automatically based on the information 50 provided by BGP-LS protocol. 52 Internet-Draft BGP-LS extend for inter-AS topology retrieval March 5, 53 2018 54 Table of Contents 56 1. Introduction ................................................ 2 57 2. Conventions used in this document............................ 3 58 3. Multi-Domain Scenarios....................................... 3 59 3.1. IS-IS/OSPF Native IP Scenario............................ 4 60 3.2. IS-IS/OSPF inter-AS TE Scenario ......................... 4 61 3.3. Proposed Solution........................................ 5 62 3.3.1. Redistributed Routes Originator TLV ................ 5 63 3.3.2. Inter-AS TE related TLVs............................ 6 64 3.3.3. Topology Reconstruction............................. 6 65 4. Security Considerations....................................... 6 66 5. IANA Considerations .......................................... 6 67 6. Conclusions .................................................. 7 68 7. References ................................................... 7 69 7.1. Normative References..................................... 7 70 7.2. Informative References .................................. 7 71 8. Acknowledgments ............................................. 8 73 1. Introduction 75 BGP-LS [RFC 7752] describes the methodology that using BGP protocol 76 to transfer the Link-State information. Such method can enable SDN 77 controller to collect the underlay network topology automatically, 78 but normally it can only get the information within one IGP domain. 79 If the operator has more than one IGP domain, and these domains 80 interconnect each other, there is no general TLV within current BGP- 81 LS to transfer the interconnect information. 83 Draft[I-D.ietf-idr-bgpls-segment-routing-epe]defines some extensions 84 for exporting BGP peering node topology information (including its 85 peers, interfaces and peering ASs) in a way that is exploitable in 86 order to compute efficient BGP Peering Engineering policies and 87 strategies. Such information can also be used to calculate the 88 interconnection topology among different IGP domains, but it requires 89 the border routers to run BGP-LS protocol to collect this information 90 and report them to the PCE/SDN controller, which restricts the 91 deployment flexibility of BGP-LS protocol. 93 Draft[I-D.ietf-idr-bgpls-segment-routing-ext]defines some extensions 94 for exporting segment routing related information. It proposes one 95 "Source Router Identifier" TLV which is defined in [RFC7794] to 96 transfer the originator information of redistributed prefixes. But 98 Internet-Draft BGP-LS extend for inter-AS topology retrieval March 5, 99 2018 100 the definition of such TLV focuses mainly on the IS-IS domain, and it 101 will only be reported when the network deploys segment routing 102 technology. 104 But beyond the segment routing scenario, draft [I-D.ietf-teas-native- 105 ip-scenarios] defines other non segment routing scenarios that the 106 PCE/SDN controller needs to get the topology information among 107 different domains automatically, and the IGP protocol in these 108 domains is not limited to IS-IS. Then we need to broader and reshape 109 the definition of "Source Router Identifier" TLV to include and cover 110 more general situations. 112 This draft analysis the situations that the PCE/SDN controller needs 113 to get the originator information of the prefixes between different 114 domains, define new TLVs to extend the BGP-LS protocol to transfer 115 the key information related to the interconnect topology. After that, 116 the SDN controller can then deduce the multi-domain topology 117 automatically based on the information from BGP-LS protocol. 119 2. Conventions used in this document 121 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 122 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 123 document are to be interpreted as described in RFC 2119 [RFC2119]. 125 3. Multi-Domain Scenarios. 127 Fig.1 illustrates the multi-domain scenarios that this draft 128 discussed. Normally, SDN Controller can get the topology of IGP A and 129 IGP B individually via the BGP-LS protocol, but it can't get the 130 topology connection information between these two IGP domains because 131 there is normally no IGP protocol run on the connected links. 133 +--------------+ 134 ---|SDN Controller---- 135 | +--------------+ | 136 | | 137 BGP-LS BGP-LS 138 | | 139 | | 140 ------ --- 141 ///- -\\\ //-- --\\ 142 / \ / \ 143 | R3-------R1--|------|-T1-------T3 | 145 Internet-Draft BGP-LS extend for inter-AS topology retrieval March 5, 146 2018 147 | | | | 148 | IGP A | | IGP B | 149 | | | | 150 | R4 ------R2--|------|-T2-------T4 | 151 \ / \ / 152 \\\- -/// \\-- --// 153 ----- --- 155 Fig.1 Multi-Domain Scenarios 157 3.1. IS-IS/OSPF Native IP Scenario 159 When the IGP A or IGP B runs IS-IS/OSPF protocol, normally the 160 operator will redistribute the prefixes of interconnect links into 161 IS-IS/OSPF protocol to ensure the inter-domain connectivity. 163 [RFC7794] defines the "IPv4/IPv6 Source Router ID" to indicate this 164 information and it will flood within the IGP domain. If BGP-LS 165 protocol that runs on one of the interior router can carry such 166 information, the PCE/SDN controller will know the anchor router of 167 the inter-domain links. Such information is needed within not only 168 for segment routing scenario as described in [I-D.ietf-idr-bgpls- 169 segment-routing-ext], but also in non segment routing scenario as 170 described in [I-D.ietf-teas-native-ip-scenarios]. 172 [RFC2328] defines the type 5 external LSA to transfer the external 173 routes; [draft-ietf-ospf-ospfv3-lsa-extend] defines the "External- 174 Prefix TLV" to transfer the external routes; these LSAs have also 175 the advertising router information that initiates the redistribute 176 activity. If such information can be reported also via the 177 "IPv4/IPv6 Source Router ID", then the PCE/SDN controller can 178 construct the underlay inter-domain topology according to procedure 179 described in section 3.5. 181 3.2. IS-IS/OSPF inter-AS TE Scenario 183 [RFC5316] and [RFC5392] define the IS-IS and OSPF extensions 184 respectively to deal with the requirements for inter-AS traffic 185 engineering. They define some new sub-TLVs(Remote AS Number IPv4 186 Remote ASBR ID IPv6 Remote ASBR ID) which are associated with the 187 inter-AS TE link TLVs to report the TE topology between different 188 domains. These TLVs are also flooding within the IGP domain. If the 190 Internet-Draft BGP-LS extend for inter-AS topology retrieval March 5, 191 2018 192 PCE/SDN controller can know these information via one of the 193 interior router that runs BGP-LS protocol, the PCE/SDN controller 194 can rebuild the inter-AS TE topology correctly. 196 3.3. Proposed Solution 198 3.3.1. Redistributed Routes Originator TLV 200 This draft proposes to define one new TLV to transfer such key 201 information; we call it "Redistributed Routes Originator" TLV. The 202 format of this TLV is illustrated below: 204 0 1 2 3 205 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 1 206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 207 | Type | Length | 208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 209 // Redistributed Routes Originator // 210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 212 Type: should be allocated by IANA. 214 Length: 4 or 16 Bytes. 216 Redistributed Routes Originator: Router ID of the redistributed 217 routes. 219 For IGP that runs IS-IS protocol, the "Redistributed Routes 220 Originator" should contain the IPv4/IPv6 address of the 221 redistributed router which is defined in [RFC7794]; 223 For IGP that runs OSPF v2/v3 protocol, the "Redistributed Routes 224 Originator" should contain the IPv4/IPv6 address of the 225 redistributed router which is included in the External LSA that 226 defined in [RFC2328] or "External-Prefix TLV" that defined in 227 [draft-ietf-ospf-ospfv3-lsa-extend]; 229 This TLV should be coincided with the IGP Route Tag TLV or OSPF 230 Route Type TLV, because these two TLVs indicate the associated 231 prefixes redistributed via other protocols. They are all under the 232 associated Prefix NLRI. 234 Internet-Draft BGP-LS extend for inter-AS topology retrieval March 5, 235 2018 236 3.3.2. Inter-AS TE related TLVs 238 This draft proposes to add three new TLVs that is associated with 239 the inter-AS TE link NLRI to transfer the information via BGP-LS, 240 which are required to build the inter-AS related topology by the 241 PCE/SDN controller. 243 The following Link Attribute TLVs are added in the BGP-LS attribute 245 with a Link NLRI: 247 +-----------+---------------------+--------------+----------------+ 248 | TLV Code | Description |IS-IS/OSPF TLV| Reference | 249 | Point | | /Sub-TLV | (RFC/Section) | 250 +-----------+---------------------+--------------+----------------+ 251 | TBD |Remote AS Number | 24/21 | [RFC5316]/3.3.1| 252 | | | | [RFC5392]/3.3.1| 253 | TBD |IPv4 Remote ASBR ID | 25/22 | [RFC5316]/3.3.2| 254 | | | | [RFC5392]/3.3.2| 255 | TBD |IPv6 Remote ASBR ID | 26/24 | [RFC5316]/3.3.3| 256 | | | | [RFC5392]/3.3.3| 257 +-----------+---------------------+--------------+----------------+ 259 3.3.3. Topology Reconstruction. 261 When SDN Controller gets such information from BGP-LS protocol, it 262 should compares the proximity of the redistributed prefixes. If they 263 are under the same scope, then it should find the corresponding 264 associated "redistributed route originator" TLV, build the link 265 between these two originators. 267 After iterating the above procedures for all of the redistributed 268 prefixes, the SDN controller can then draw the connection topology 269 between different domains automatically. 271 4. Security Considerations 273 TBD 275 5. IANA Considerations 277 TBD 279 Internet-Draft BGP-LS extend for inter-AS topology retrieval March 5, 280 2018 281 6. Conclusions 283 TBD 285 7. References 287 7.1. Normative References 289 [RFC2328] J. Moy, "OSPF Version 2",RFC2328, April 1998 290 http://www.rfc-editor.org/info/rfc2328 292 [RFC 5316] M. Chen, R. Zhang, X. Duan, "ISIS Extensions in Support 293 of Inter-Autonomous System (AS) MPLS and GMPLS Traffic Engineering", 294 RFC5316, December 2008, http://www.rfc-editor.org/info/rfc5316 296 [RFC5392] M. Chen, R. Zhang, X. Duan, "OSPF Extensions in Support of 297 Inter-Autonomous System (AS) MPLS and GMPLS Traffic Engineering", 298 RFC5392, January 2009, http://www.rfc-editor.org/info/rfc5392 300 [RFC7752] H. Gredler, Ed., J. Medved, S. Previdi, A. Farrel, S. Ray, 301 "North-Bound Distribution of Link-State and Traffic Engineering (TE) 302 Information Using BGP ", RFC7752, March 2016, 303 https://tools.ietf.org/html/rfc7752 305 [RFC7794] L. Ginsberg, Ed., B. Decraene, S. Previdi, X. Xu, U. 306 Chunduri, "IS-IS Prefix Attributes for Extended IPv4 and IPv6 307 Reachability", RFC7794, March 2016 309 7.2. Informative References 311 [I-D.ietf-idr-bgpls-segment-routing-epe] 313 S. Previdi, C. Filsfils, K. Patel, S. Ray, J. Dong, "BGP-LS 314 extensions for Segment Routing BGP Egress Peer Engineering", 316 Internet-Draft BGP-LS extend for inter-AS topology retrieval March 5, 317 2018 318 draft-ietf-idr-bgpls-segment-routing-epe(work in progress), 319 December, 2017 321 [I-D.ietf-idr-bgpls-segment-routing-ext] 323 S.Previdi, K.Talaulikar, C.Filsfils, H.Gredler, M.Chen, "BGP 324 Link-State extensions for Segment Routing", [draft-ietf-idr-bgp- 325 ls-segment-routing-ext](work in progress), January, 2018 327 [I-D.ietf-teas-native-ip-scenarios] 329 A. Wang, Xiaohong Huang, Caixia Kou, Lu Huang, Penghui Mi, "CCDR 330 Scenario, Simulation and Suggestion", [draft-ietf-teas-native- 331 ip-scenarios](work in progress), February, 2018 333 [draft-ietf-ospf-ospfv3-lsa-extend] 335 A.Lindem, A.Roy, D.Goethals, V.Reddy Vallem, "OSPFv3 LSA 336 Extendibility", https://datatracker.ietf.org/doc/draft-ietf-ospf- 337 ospfv3-lsa-extend/ (work in progess), January 2018 339 8. Acknowledgments 341 TBD. 343 Authors' Addresses 345 Aijun Wang 346 China Telecom 347 Beiqijia Town, Changping District 348 Beijing,China 350 Email: wangaj.bri@chinatelecom.cn