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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC5305' is defined on line 453, but no explicit reference was found in the text ** Obsolete normative reference: RFC 5316 (Obsoleted by RFC 9346) ** Obsolete normative reference: RFC 7752 (Obsoleted by RFC 9552) ** Downref: Normative reference to an Informational RFC: RFC 8735 == Outdated reference: A later version (-08) exists of draft-wang-lsr-passive-interface-attribute-00 Summary: 3 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IDR Working Group A. Wang 3 Internet-Draft China Telecom 4 Intended status: Standards Track H. Chen 5 Expires: October 4, 2020 Futurewei 6 K. Talaulikar 7 Cisco Systems 8 S. Zhuang 9 Huawei Technologies 10 April 2, 2020 12 BGP-LS Extension for Inter-AS Topology Retrieval 13 draft-ietf-idr-bgpls-inter-as-topology-ext-08 15 Abstract 17 This document describes the process to build Border Gateway Protocol- 18 Link State (BGP-LS) key parameters in inter-domain scenario, defines 19 one new BGP-LS Network Layer Reachability Information (NLRI) type 20 (Stub Link NLRI) and some new inter Autonomous (inter-AS) Traffic 21 Engineering (TE) related Type-Length-Values (TLVs) for BGP-LS to let 22 Software Definition Network (SDN) controller retrieve the network 23 topology automatically under various inter-AS environments. 25 Such extension and process can enable the network operator to collect 26 the interconnect information between different domains and then 27 calculate the overall network topology automatically based on the 28 information provided by BGP-LS protocol. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at https://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on October 4, 2020. 47 Copyright Notice 49 Copyright (c) 2020 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (https://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 2. Conventions used in this document . . . . . . . . . . . . . . 3 66 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 67 4. Inter-AS Domain Scenarios. . . . . . . . . . . . . . . . . . 3 68 5. Stub Link NLRI . . . . . . . . . . . . . . . . . . . . . . . 4 69 5.1. Inter-AS Native IP Scenario . . . . . . . . . . . . . . . 5 70 5.2. Inter-AS TE Scenario . . . . . . . . . . . . . . . . . . 6 71 6. Inter-AS TE NLRI related TLVs . . . . . . . . . . . . . . . . 6 72 6.1. Remote AS Number TLV . . . . . . . . . . . . . . . . . . 7 73 6.2. IPv4 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7 74 6.3. IPv6 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 8 75 7. Topology Reconstruction. . . . . . . . . . . . . . . . . . . 8 76 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 77 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 78 9.1. New BGP-LS NLRI type . . . . . . . . . . . . . . . . . . 9 79 9.2. New Link Descriptors . . . . . . . . . . . . . . . . . . 10 80 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 10 81 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 82 11.1. Normative References . . . . . . . . . . . . . . . . . . 10 83 11.2. Informative References . . . . . . . . . . . . . . . . . 11 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 86 1. Introduction 88 BGP-LS [RFC7752] describes the methodology that using BGP protocol to 89 transfer the Link-State information. Such method can enable SDN 90 controller to collect the underlay network topology automatically, 91 but normally it can only get the information within one Interior 92 Gateway Protocol (IGP) domain. If the operator has more than one IGP 93 domain, and these domains interconnect with each other, there is no 94 mechanic within current BGP- LS to transfer the interconnect topology 95 information. 97 Draft [I-D.ietf-idr-bgpls-segment-routing-epe] defines some 98 extensions for exporting BGP peering node topology information 99 (including its peers, interfaces and peering ASs) in a way that is 100 exploitable in order to compute efficient BGP Peering Engineering 101 policies and strategies. Such information can also be used to 102 calculate the interconnection topology among different IGP domains, 103 but it requires every border router to run BGP-LS protocol and report 104 the information to SDN controller. Considering there will be several 105 border routers on the network boundary, such solution restricts its 106 deployment flexibility. 108 This draft analysis the situations that the SDN controller needs to 109 get the interconnected topology information between different AS 110 domains, defines the new Stub Link NLRI and some new TLVs within the 111 BGP-LS protocol to transfer the key information related to them. 112 After that, the SDN controller can then deduce the multi-domain 113 topology automatically based on the information from BGP-LS protocol. 115 2. Conventions used in this document 117 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 118 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 119 document are to be interpreted as described in RFC 2119 [RFC2119] . 121 3. Terminology 123 The following terms are defined in this document: 125 o IDCs: Internet Data Centers 127 o MAN: Metrio-Area-Network 129 o SDN: Software Definition Network 131 4. Inter-AS Domain Scenarios. 133 Figure 1 illustrates the multi-domain scenarios that this draft 134 discusses. Normally, SDN Controller can get the topology of IGP A 135 and IGP B individually via the BGP-LS protocol, but it can't get the 136 topology connection information between these two IGP domains because 137 there is generally no IGP protocol run on the connected links. 139 +-----------------+ 140 +----+IP SDN Controller+----+ 141 | +-----------------+ | 142 | | 143 |BGP-LS |BGP-LS 144 | | 145 +---------------+-----+ +-----+--------------+ 146 | +--+ +-++ ++-+ +-++ +|-+ +--+| 147 | |S1+--------+S2+---+B1+-----------+B2+---+T1+--------+T2|| 148 | +-++ N1 +-++ ++-+ +-++ ++++ N2 +-++| 149 | | | | | || | | 150 | | | | | || | | 151 | +-++ +-++ ++-+ +-++ ++++ +-++| 152 | |S4+--------+S3+---+B3+-----------+B4+---+T3+--------+T4|| 153 | +--+ +--+ ++-+ +-++ ++-+ +--+| 154 | | | | 155 | | | | 156 | IGP A | | IGP B | 157 +---------------------+ +--------------------+ 159 Figure 1: Inter-AS Domain Scenarios 161 5. Stub Link NLRI 163 [RFC7752] defines four NLRI types(Node NLRI, Link NLRI, IPv4 Topology 164 Prefix NLRI, IPv6 Topology Prefix NLRI) to transfer the topology and 165 prefix information. For inter-as link, the two ends of the link 166 locates in different IGP domains, then it is not appropriate to 167 transfer their information within the current defined NLRI types. 169 This draft defines one new NLRI type, called Stub Link NLRI, which is 170 coded as the following format: 172 0 1 2 3 173 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 1 174 +-+-+-+-+-+-+-+-+ 175 | Protocol-ID | 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 177 | Identifier | 178 | (64 bits) | 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 // Local Node Descriptors (variable) // 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 // Stub Link Descriptors (variable) // 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 185 Figure 2: Stub Link NLRI Format 187 The "Protocol-ID" should be set to the value that indicates "Direct" 188 protocol. 190 The semantics of "Local Node Descriptors" and "Stub Link Descriptors" 191 are same as that defined in [RFC7752] for "Node Descriptors" and 192 "Link Descriptor". 194 This newly defined NLRI can be used to describe the link that has 195 only one end located within the IGP domain, as described in the 196 following sections. 198 5.1. Inter-AS Native IP Scenario 200 Draft [RFC8735] describes the situation that operator needs some 201 traffic engineering solution for the inter-as native IP environment. 202 In such situation, different domain may run different IGP protocol. 203 The operator needs to know the inter-as topology first to calculate 204 the end to end optimal path centrally. 206 When IGP A or IGP B in Figure 1 runs native IS-IS/OSPF protocol, the 207 operator can use passive feature for the inter-domain links to let 208 the routers within the IGP domain know these links. Such stub links 209 information can then be carried within the Stub Link NLRI reported 210 via the BGP-LS protocol to the SDN controller. 212 For OSPF, when the interface is configured as passive, the "Linktype" 213 field in corresponding Router LSA will be set to 3, to indicate it 214 connects with stub network. Other routers in the IGP domain can 215 identify such interfaces via this characteristics, and report them 216 via the newly defined "Stub Link NLRI". 218 For ISIS, [I-D.wang-lsr-passive-interface-attribute] describe the 219 method to label the passive interfaces within the network. The 220 router that runs BGP-LS can extract these passive interfaces from 221 other interfaces that participate in the IGP protocol and report them 222 via the newly defined "Stub Link NLRI". Or else such router can only 223 extract such information from the adjacency of interfaces. If the 224 number of adjacency of the interface is zero, then such interfaces 225 can be reported via the newly defined "Stub Link NLRI". 227 The "Local Node Descriptors" should describe the characteristics of 228 ASBRs that are connected these stub links. 230 When such information is reported via the BGP-LS protocol, the SDN 231 controller can construct the underlay inter-domain topology according 232 to procedure described in Section 7 234 5.2. Inter-AS TE Scenario 236 When IGP A or IGP B in Figure 1 runs IS-IS TE/OSPF-TE protocol, 237 [RFC5316] and [RFC5392] define IS-IS and OSPF extensions respectively 238 to deal with the situation for inter-AS traffic engineering. Three 239 new sub-TLVs(Remote AS Number、IPv4 Remote ASBR ID、IPv6 240 Remote ASBR ID) which are associated with the inter-AS TE link are 241 defined. 243 These TLVs are flooded within the IGP domain automatically. They 244 should be carried within the newly defined Stub Link NLRI within the 245 BGP-LS protocol, as the descriptors for the inter-AS stub link. 247 The "Local Node Descriptors" should describe the the characteristics 248 of ASBRs that are connected these inter-AS TE links. 250 If the SDN controller knows these information via one of the interior 251 router that runs BGP-LS protocol, the SDN controller can rebuild the 252 inter-AS TE topology correctly according to the procedure described 253 in Section 7 255 6. Inter-AS TE NLRI related TLVs 257 This draft proposes to add three new TLVs that is included within the 258 Stub Link NLRI to transfer the information via BGP-LS, which are 259 required to build the inter-AS TE related topology by the SDN 260 controller. 262 The following Link Descriptor TLVs are added into the BGP-LS protocol 263 : 265 +-----------+---------------------+--------------+----------------+ 266 | TLV Code | Description |IS-IS/OSPF TLV| Reference | 267 | Point | | /Sub-TLV | (RFC/Section) | 268 +-----------+---------------------+--------------+----------------+ 269 | TBD |Remote AS Number | 24/21 | [RFC5316]/3.3.1| 270 | | | | [RFC5392]/3.3.1| 271 | TBD |IPv4 Remote ASBR ID | 25/22 | [RFC5316]/3.3.2| 272 | | | | [RFC5392]/3.3.2| 273 | TBD |IPv6 Remote ASBR ID | 26/24 | [RFC5316]/3.3.3| 274 | | | | [RFC5392]/3.3.3| 275 +-----------+---------------------+--------------+----------------+ 276 Figure 3: Link Descriptor TLVs 278 Detail encoding of these TLVs are synchronized with the corresponding 279 parts in [RFC5316] and [RFC5392], which keeps the BGP-LS protocol 280 agnostic to the underly protocol. 282 6.1. Remote AS Number TLV 284 A new TLV, the remote AS number TLV, is defined for inclusion in the 285 link descriptor when advertising inter-AS TE links. The remote AS 286 number TLV specifies the AS number of the neighboring AS to which the 287 advertised link connects. 289 The remote AS number TLV is TLV type TBD (see Section 9 ) and is 4 290 octets in length. The format is as follows: 292 0 1 2 3 293 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 1 294 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 295 | Type | Length | 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 297 | Remote AS Number | 298 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 299 Figure 4: Remote AS Number TLV Format 301 The Remote AS number field has 4 octets. When only 2 octets are used 302 for the AS number, as in current deployments, the left (high-order) 2 303 octets MUST be set to 0. The remote AS number TLV MUST be included 304 when a router advertises an inter-AS TE link. 306 6.2. IPv4 Remote ASBR ID 308 A new TLV, which is referred to as the IPv4 remote ASBR ID TLV, is 309 defined for inclusion in the link descriptor when advertising inter- 310 AS TE links. The IPv4 remote ASBR ID TLV specifies the IPv4 311 identifier of the remote ASBR to which the advertised inter-AS link 312 connects. This could be any stable and routable IPv4 address of the 313 remote ASBR. Use of the TE Router ID as specified in the Traffic 314 Engineering router ID TLV [RFC5316] is RECOMMENDED. 316 The IPv4 remote ASBR ID TLV is TLV type TBD (see Section 9) and is 4 317 octets in length. The format of the IPv4 remote ASBR ID sub-TLV is 318 as follows: 320 0 1 2 3 321 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 1 322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 323 | Type | Length | 324 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 325 | Remote ASBR ID | 326 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 327 Figure 5: IPv4 Remote ASBR ID TLV Format 329 The IPv4 remote ASBR ID TLV MUST be included if the neighboring ASBR 330 has an IPv4 address. If the neighboring ASBR does not have an IPv4 331 address (not even an IPv4 TE Router ID), the IPv6 remote ASBR ID TLV 332 MUST be included instead. An IPv4 remote ASBR ID TLV and IPv6 remote 333 ASBR ID TLV MAY both be present in an inter-AS TE link NLRI. 335 6.3. IPv6 Remote ASBR ID 337 A new TLV, which is referred to as the IPv6 remote ASBR ID TLV, is 338 defined for inclusion in the link descriptor when advertising inter- 339 AS links. The IPv6 remote ASBR ID TLV specifies the IPv6 identifier 340 of the remote ASBR to which the advertised inter-AS link connects. 341 This could be any stable and routable IPv6 address of the remote 342 ASBR. Use of the TE Router ID as specified in the IPv6 Traffic 343 Engineering router ID TLV [RFC5316] is RECOMMENDED. 345 The IPv6 remote ASBR ID TLV is TLV type TBD (see Section 9) and is 16 346 octets in length. The format of the IPv6 remote ASBR ID TLV is as 347 follows: 349 0 1 2 3 350 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 1 351 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 352 | Type | Length | 353 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 354 | Remote ASBR ID | 355 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 356 | Remote ASBR ID (continued) | 357 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 358 | Remote ASBR ID (continued) | 359 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 360 | Remote ASBR ID (continued) | 361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 362 Figure 6: IPv6 Remote ASBR ID TLV Format 364 The IPv6 remote ASBR ID TLV MUST be included if the neighboring ASBR 365 has an IPv6 address. If the neighboring ASBR does not have an IPv6 366 address, the IPv4 remote ASBR ID TLV MUST be included instead. An 367 IPv4 remote ASBR ID TLV and IPv6 remote ASBR ID TLV MAY both be 368 present in an inter-AS TE link NLRI. 370 7. Topology Reconstruction. 372 When SDN controller gets such information from BGP-LS protocol, it 373 should compares the proximity of these stub links. If they are under 374 the same network scope and in different AS, then it should find the 375 corresponding associated router information, build the link between 376 these two border routers. 378 If the prefixes reported via the "Stub Link" NLRI are under the same 379 network scope, and in the same AS, the SDN controller can then 380 determine there is some IGP adjacency irregular. The usage of such 381 information is out of scope of this draft. 383 After iterating the above procedures for all of the stub links, the 384 SDN controller can then retrieve the connection topology between 385 different domains automatically. 387 8. Security Considerations 389 It is common for one operator to occupy several IGP domains that are 390 composited by its backbone network and several MAN(Metrio-Area- 391 Network)s/Internet Data Centers (IDCs). When they do traffic 392 engineering which spans MAN, Backbone and IDC, they need to know the 393 inter-as topology via the process described in this draft. Using the 394 passive interface features or configuring the Traffic Engineering 395 (TE) parameters on the interconnect links will not spread the 396 topology fluctuation across each other domain. 398 9. IANA Considerations 400 This document defines: 402 o A new BGP NLRI Type: Stub Link NLRI. The codepoint is from the 403 "BGP-LS NLRI Types" 405 o Three new Link Descriptors TLV: Remote AS Number TLV, IPv4 Remote 406 ASBR ID, IPv6 Remote ASBR ID. The codepoint are from "BGP-LS Node 407 Descriptor, Link Descriptor, Prefix Descriptor, and Attribute 408 TLVs" registry. 410 9.1. New BGP-LS NLRI type 412 This document defines a new value in the registry "BGP-LS NLRI 413 Types": 415 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 416 | Code Point | Description | Status | 417 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 | TBD | Stub Link NLRI | Allocation from IANA | 419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 420 Figure 7: Stub Link NLRI Codepoint 422 9.2. New Link Descriptors 424 This document defines three new values in the registry "BGP-LS Node 425 Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs": 427 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 428 | Code Point | Description | Status | 429 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 430 | TBD | Remote AS Number | Allocation from IANA | 431 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 432 | TBD |IPv4 Remote ASBR ID| Allocation from IANA | 433 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 434 | TBD |IPv6 Remote ASBR ID| Allocation from IANA | 435 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 436 Figure 8: BGP-LS Link Descriptors TLV 438 10. Acknowledgement 440 The author would like to thank Acee Lindem, Jie Dong, Shaowen Ma, 441 Jeff Tantsura and Dhruv Dhody for their valuable comments and 442 suggestions. 444 11. References 446 11.1. Normative References 448 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 449 Requirement Levels", BCP 14, RFC 2119, 450 DOI 10.17487/RFC2119, March 1997, 451 . 453 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 454 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 455 2008, . 457 [RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in 458 Support of Inter-Autonomous System (AS) MPLS and GMPLS 459 Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316, 460 December 2008, . 462 [RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in 463 Support of Inter-Autonomous System (AS) MPLS and GMPLS 464 Traffic Engineering", RFC 5392, DOI 10.17487/RFC5392, 465 January 2009, . 467 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 468 S. Ray, "North-Bound Distribution of Link-State and 469 Traffic Engineering (TE) Information Using BGP", RFC 7752, 470 DOI 10.17487/RFC7752, March 2016, 471 . 473 [RFC8735] Wang, A., Huang, X., Kou, C., Li, Z., and P. Mi, 474 "Scenarios and Simulation Results of PCE in a Native IP 475 Network", RFC 8735, DOI 10.17487/RFC8735, February 2020, 476 . 478 11.2. Informative References 480 [I-D.ietf-idr-bgpls-segment-routing-epe] 481 Previdi, S., Talaulikar, K., Filsfils, C., Patel, K., Ray, 482 S., and J. Dong, "BGP-LS extensions for Segment Routing 483 BGP Egress Peer Engineering", draft-ietf-idr-bgpls- 484 segment-routing-epe-19 (work in progress), May 2019. 486 [I-D.wang-lsr-passive-interface-attribute] 487 Wang, A. and Z. Hu, "Passive Interface Attribute", draft- 488 wang-lsr-passive-interface-attribute-00 (work in 489 progress), January 2020. 491 Authors' Addresses 493 Aijun Wang 494 China Telecom 495 Beiqijia Town, Changping District 496 Beijing, Beijing 102209 497 China 499 Email: wangaj3@chinatelecom.cn 501 Huaimo Chen 502 Futurewei 503 Boston, MA 504 USA 506 Email: hchen@futurewei.com 508 Ketan Talaulikar 509 Cisco Systems 511 Email: ketant@cisco.com 512 Shunwan Zhuang 513 Huawei Technologies 514 Huawei Building, No.156 Beiqing Rd. 515 Beijing 100095 516 China 518 Email: zhuangshunwan@huawei.com