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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group D. Dhody 3 Internet-Draft S. Peng 4 Intended status: Experimental Huawei Technologies 5 Expires: August 24, 2021 Y. Lee 6 Samsung Electronics 7 D. Ceccarelli 8 Ericsson 9 A. Wang 10 China Telecom 11 G. Mishra 12 Verizon Inc. 13 February 20, 2021 15 PCEP extensions for Distribution of Link-State and TE Information 16 draft-dhodylee-pce-pcep-ls-20 18 Abstract 20 In order to compute and provide optimal paths, a Path Computation 21 Elements (PCEs) require an accurate and timely Traffic Engineering 22 Database (TED). Traditionally, this TED has been obtained from a 23 link state (LS) routing protocol supporting the traffic engineering 24 extensions. 26 This document extends the Path Computation Element Communication 27 Protocol (PCEP) with Link-State and TE Information as an experimental 28 extension. 30 Requirements Language 32 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 33 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 34 "OPTIONAL" in this document are to be interpreted as described in BCP 35 14 [RFC2119] [RFC8174] when, and only when, they appear in all 36 capitals, as shown here. 38 Status of This Memo 40 This Internet-Draft is submitted in full conformance with the 41 provisions of BCP 78 and BCP 79. 43 Internet-Drafts are working documents of the Internet Engineering 44 Task Force (IETF). Note that other groups may also distribute 45 working documents as Internet-Drafts. The list of current Internet- 46 Drafts is at https://datatracker.ietf.org/drafts/current/. 48 Internet-Drafts are draft documents valid for a maximum of six months 49 and may be updated, replaced, or obsoleted by other documents at any 50 time. It is inappropriate to use Internet-Drafts as reference 51 material or to cite them other than as "work in progress." 53 This Internet-Draft will expire on August 24, 2021. 55 Copyright Notice 57 Copyright (c) 2021 IETF Trust and the persons identified as the 58 document authors. All rights reserved. 60 This document is subject to BCP 78 and the IETF Trust's Legal 61 Provisions Relating to IETF Documents 62 (https://trustee.ietf.org/license-info) in effect on the date of 63 publication of this document. Please review these documents 64 carefully, as they describe your rights and restrictions with respect 65 to this document. Code Components extracted from this document must 66 include Simplified BSD License text as described in Section 4.e of 67 the Trust Legal Provisions and are provided without warranty as 68 described in the Simplified BSD License. 70 Table of Contents 72 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 73 1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5 74 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 75 3. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 6 76 4. Requirements for PCEP extensions . . . . . . . . . . . . . . 7 77 5. New Functions to distribute link-state (and TE) via PCEP . . 8 78 6. Overview of Extensions to PCEP . . . . . . . . . . . . . . . 8 79 6.1. New Messages . . . . . . . . . . . . . . . . . . . . . . 8 80 6.2. Capability Advertisement . . . . . . . . . . . . . . . . 8 81 6.3. Initial Link-State (and TE) Synchronization . . . . . . . 9 82 6.3.1. Optimizations for LS Synchronization . . . . . . . . 11 83 6.4. LS Report . . . . . . . . . . . . . . . . . . . . . . . . 12 84 7. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 12 85 8. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 12 86 8.1. LS Report Message . . . . . . . . . . . . . . . . . . . . 12 87 8.2. The PCErr Message . . . . . . . . . . . . . . . . . . . . 13 88 9. Objects and TLV . . . . . . . . . . . . . . . . . . . . . . . 13 89 9.1. TLV Format . . . . . . . . . . . . . . . . . . . . . . . 14 90 9.2. Open Object . . . . . . . . . . . . . . . . . . . . . . . 14 91 9.2.1. LS Capability TLV . . . . . . . . . . . . . . . . . . 14 92 9.3. LS Object . . . . . . . . . . . . . . . . . . . . . . . . 15 93 9.3.1. Routing Universe TLV . . . . . . . . . . . . . . . . 16 94 9.3.2. Route Distinguisher TLV . . . . . . . . . . . . . . . 17 95 9.3.3. Virtual Network TLV . . . . . . . . . . . . . . . . . 18 96 9.3.4. Local Node Descriptors TLV . . . . . . . . . . . . . 18 97 9.3.5. Remote Node Descriptors TLV . . . . . . . . . . . . . 19 98 9.3.6. Node Descriptors Sub-TLVs . . . . . . . . . . . . . . 19 99 9.3.7. Link Descriptors TLV . . . . . . . . . . . . . . . . 20 100 9.3.8. Prefix Descriptors TLV . . . . . . . . . . . . . . . 21 101 9.3.9. PCEP-LS Attributes . . . . . . . . . . . . . . . . . 21 102 9.3.9.1. Node Attributes TLV . . . . . . . . . . . . . . . 21 103 9.3.9.2. Link Attributes TLV . . . . . . . . . . . . . . . 22 104 9.3.9.3. Prefix Attributes TLV . . . . . . . . . . . . . . 22 105 9.3.10. Removal of an Attribute . . . . . . . . . . . . . . . 23 106 10. Other Considerations . . . . . . . . . . . . . . . . . . . . 23 107 10.1. Inter-AS Links . . . . . . . . . . . . . . . . . . . . . 23 108 11. Security Considerations . . . . . . . . . . . . . . . . . . . 23 109 12. Manageability Considerations . . . . . . . . . . . . . . . . 24 110 12.1. Control of Function and Policy . . . . . . . . . . . . . 24 111 12.2. Information and Data Models . . . . . . . . . . . . . . 24 112 12.3. Liveness Detection and Monitoring . . . . . . . . . . . 25 113 12.4. Verify Correct Operations . . . . . . . . . . . . . . . 25 114 12.5. Requirements On Other Protocols . . . . . . . . . . . . 25 115 12.6. Impact On Network Operations . . . . . . . . . . . . . . 25 116 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 117 13.1. PCEP Messages . . . . . . . . . . . . . . . . . . . . . 25 118 13.2. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 26 119 13.3. LS Object . . . . . . . . . . . . . . . . . . . . . . . 26 120 13.4. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 27 121 13.5. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 27 122 13.6. PCEP-LS Sub-TLV Type Indicators . . . . . . . . . . . . 28 123 14. TLV Code Points Summary . . . . . . . . . . . . . . . . . . . 29 124 15. Implementation Status . . . . . . . . . . . . . . . . . . . . 29 125 15.1. Hierarchical Transport PCE controllers . . . . . . . . . 29 126 15.2. ONOS-based Controller (MDSC and PNC) . . . . . . . . . . 30 127 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30 128 17. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 129 17.1. Normative References . . . . . . . . . . . . . . . . . . 30 130 17.2. Informative References . . . . . . . . . . . . . . . . . 31 131 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 35 132 A.1. All Nodes . . . . . . . . . . . . . . . . . . . . . . . . 35 133 A.2. Designated Node . . . . . . . . . . . . . . . . . . . . . 36 134 A.3. Between PCEs . . . . . . . . . . . . . . . . . . . . . . 36 135 Appendix B. Contributor Addresses . . . . . . . . . . . . . . . 38 136 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38 138 1. Introduction 140 In Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS), 141 a Traffic Engineering Database (TED) is used in computing paths for 142 connection-oriented packet services and for circuits. The TED 143 contains all relevant information that a Path Computation Element 144 (PCE) needs to perform its computations. It is important that the 145 TED be 'complete and accurate' each time the PCE performs a path 146 computation. 148 In MPLS and GMPLS, interior gateway routing protocols (Interior 149 Gateway Protocol (IGPs)) have been used to create and maintain a copy 150 of the TED at each node running the IGP. One of the benefits of the 151 PCE architecture [RFC4655] is the use of computationally more 152 sophisticated path computation algorithms and the realization that 153 these may need enhanced processing power (not necessarily available 154 at each node). 156 Section 4.3 of [RFC4655] describes the potential load of the TED on a 157 network node and proposes an architecture where the TED is maintained 158 by the PCE rather than the network nodes. However, it does not 159 describe how a PCE would obtain the information needed to populate 160 its TED. PCE may construct its TED by participating in the IGP 161 ([RFC3630] and [RFC5305] for MPLS-TE; [RFC4203] and [RFC5307] for 162 GMPLS). An alternative mechanism is offered by BGP-LS 163 [I-D.ietf-idr-rfc7752bis] . 165 [RFC8231] describes a set of extensions to PCEP to provide stateful 166 control. A stateful PCE has access to not only the information 167 carried by the network's IGP, but also the set of active paths and 168 their reserved resources for its computations. Path Computation 169 Client (PCC) can delegate the rights to modify the LSP parameters to 170 an Active Stateful PCE. This requires PCE to quickly be updated on 171 any changes in the topology/TED, so that PCE can meet the need for 172 updating LSPs effectively and in a timely manner. The fastest way 173 for a PCE to be updated on TED changes is via a direct session with 174 each network node and with an incremental update from each network 175 node with only the attributes that gets modified. 177 [RFC8281] describes the setup, maintenance, and teardown of PCE- 178 initiated LSPs under the stateful PCE model, without the need for 179 local configuration on the PCC, thus allowing for a dynamic network 180 that is centrally controlled and deployed. This model requires 181 timely topology and TED update at the PCE. 183 [RFC5440] describes the specifications for the Path Computation 184 Element Communication Protocol (PCEP). PCEP specifies the 185 communication between a PCC and a PCE, or between two PCEs based on 186 the PCE architecture [RFC4655]. 188 This document describes a mechanism by which link-state and TE 189 information can be collected from networks and shared with PCE using 190 the PCEP itself. This is achieved using a new PCEP message format. 192 The mechanism is applicable to physical and virtual links as well as 193 further subjected to various policies. 195 A network node maintains one or more databases for storing link-state 196 and TE information about nodes and links in any given area. Link 197 attributes stored in these databases include: local/remote IP 198 addresses, local/remote interface identifiers, link metric, and TE 199 metric, link bandwidth, reservable bandwidth, per CoS class 200 reservation state, preemption, and Shared Risk Link Groups (SRLG). 201 The node's PCEP process can retrieve topology from these databases 202 and distribute it to a PCE, either directly or via another PCEP 203 Speaker, using the encoding specified in this document. 205 Further [RFC6805] describes Hierarchical-PCE architecture, where a 206 parent PCE maintains a domain topology map. To build this domain 207 topology map, the child PCE can carry the border nodes and inter- 208 domain link information to the parent PCE using the mechanism 209 described in this document. Further as described in [RFC8637], the 210 child PCE can also transport abstract Link-State and TE information 211 from child PCE to a Parent PCE using the mechanism described in this 212 document to build an abstract topology at the parent PCE. 214 [RFC8231] describe LSP state synchronization between PCCs and PCEs in 215 case of stateful PCE. This document does not make any change to the 216 LSP state synchronization process. The mechanism described in this 217 document are on top of the existing LSP state synchronization. 219 1.1. Scope 221 The procedures described in this document are experimental. The 222 experiment is intended to enable research for the usage of PCEP to 223 populate the Link-State and TE Information from a PCC to the PCE. 224 For this purpose, this document specifies new PCEP message and 225 object/TLVs. 227 The experiment will end three years after the RFC is published. At 228 that point, the RFC authors will attempt to determine how widely this 229 has been implemented and deployed. 231 The new message introduced by this document will not be understood by 232 legacy implementations. On receiving the message, a legacy 233 implementation will behave according to the rules for a unknown 234 message as per [RFC5440]. It is assumed that this experiment will be 235 conducted only when both the PCE and PCC form part of the experiment. 236 It is possible that a PCC or PCE can operate with peers, some of 237 which form part of the experiment and some that do not. In this 238 case, the capability exchange required before using this extension 239 would take care of the mismatch. 241 When the results of implementation and deployment are available, this 242 document will be updated and refined, and then it could be moved from 243 Experimental to Standards Track. 245 2. Terminology 247 The terminology is as per [RFC4655] and [RFC5440]. 249 3. Applicability 251 The mechanism specified in this draft is applicable to deployments: 253 o Where there is no IGP or BGP-LS running in the network. 255 o Where there is no IGP or BGP-LS running at the PCE to learn link- 256 state and TE information. 258 o Where there is IGP or BGP-LS running but with a need for a faster 259 and direct TE and link-state population and convergence at the 260 PCE. 262 * A PCE may receive partial information (say basic TE, link- 263 state) from IGP and other information (optical and impairment) 264 from PCEP. 266 * A PCE may receive an incremental update (as opposed to the full 267 (entire) information of the node/link). 269 * A PCE may receive full information from both existing 270 mechanisms (IGP or BGP-LS) and PCEP. 272 o Where there is a need for transporting (abstract) Link-State and 273 TE information from child PCE to a Parent PCE in H-PCE [RFC6805]; 274 as well as for Provisioning Network Controller (PNC) to Multi- 275 Domain Service Coordinator (MDSC) in Abstraction and Control of TE 276 Networks (ACTN) [RFC8453]. 278 o Where there is an existing PCEP session between all the nodes and 279 the PCE-based central controller (PCECC) [RFC8283], and the 280 operator would like to use PCEP as direct southbound interface to 281 all the nodes in the network. This enables the operator to use 282 PCEP as a single direct protocol between the controller and all 283 the nodes in the network. In this mode, all nodes send only the 284 local information. 286 Based on the local policy and deployment scenario, a PCC chooses to 287 send only local information or both local and remote learned 288 information. How a PCE manages the link-state (and TE) information 289 is implementation specific and thus out of the scope of this 290 document. 292 The prefix information in PCEP-LS can also help in determining the 293 domain of the tunnel destination in the H-PCE (and ACTN) scenario. 294 Section 4.5 of [RFC6805] describe various mechanisms and procedures 295 that might be used, PCEP-LS provides a simple mechanism to exchange 296 this information within PCEP. 298 [RFC8453] defines three types of topology abstraction - (1) Native/ 299 White Topology; (2) Black Topology; and (3) Grey Topology. Based on 300 the local policy, the PNC (or child PCE) would share the domain 301 topology to the MDSC (or Parent PCE) based on the abstraction type. 302 The protocol extensions defined in this document can carry any type 303 of topology abstraction. 305 4. Requirements for PCEP extensions 307 Following key requirements associated with link-state (and TE) 308 distribution are identified for PCEP: 310 1. The PCEP speaker supporting this draft MUST have a mechanism to 311 advertise the Link-State (and TE) distribution capability. 313 2. PCC supporting this draft MUST have the capability to report the 314 link-state (and TE) information to the PCE. This MUST include 315 self originated (local) information and MAY also allow remote 316 information learned via routing protocols. PCC MUST be capable 317 to do the initial bulk sync at the time of session initialization 318 as well as any changes there after. 320 3. A PCE MAY learn link-state (and TE) from PCEP as well as from 321 existing mechanisms like IGP/BGP-LS. PCEP extensions MUST have a 322 mechanism to correlate the information learned via other means. 323 There MUST NOT be any changes to the existing link-state (and TE) 324 population mechanism via IGP/BGP-LS. PCEP extension SHOULD keep 325 the properties in a protocol (IGP or BGP-LS) neutral way, such 326 that an implementation need not know about any OSPF or IS-IS or 327 BGP-LS protocol specifics. 329 4. It SHOULD be possible to encode only the changes in link-state 330 (and TE) properties (after the initial sync) in PCEP messages. 331 This leads to faster convergence. 333 5. The same mechanism SHOULD be used for both MPLS TE as well as 334 GMPLS, optical, and impairment aware properties. 336 6. The same mechanism SHOULD be used for PCE to PCE Link-state (and 337 TE) synchronization. 339 5. New Functions to distribute link-state (and TE) via PCEP 341 Several new functions are required in PCEP to support distribution of 342 link-state (and TE) information. A function can be initiated either 343 from a PCC towards a PCE (C-E) or from a PCE towards a PCC (E-C). 344 The new functions are: 346 o Capability advertisement (E-C,C-E): both the PCC and the PCE MUST 347 announce during PCEP session establishment that they support PCEP 348 extensions for distribution of link-state (and TE) information 349 defined in this document. 351 o Link-State (and TE) synchronization (C-E): after the session 352 between the PCC and a PCE is initialized, the PCE must learn Link- 353 State (and TE) information before it can perform path 354 computations. In the case of stateful PCE it is RECOMMENDED that 355 this operation be done before LSP state synchronization. 357 o Link-State (and TE) Report (C-E): a PCC sends an LS (and TE) 358 report to a PCE whenever the Link-State and TE information 359 changes. 361 6. Overview of Extensions to PCEP 363 6.1. New Messages 365 In this document, we define a new PCEP message called LS Report 366 (LSRpt), a PCEP message sent by a PCC to a PCE to report link-state 367 (and TE) information. Each LS Report in an LSRpt message can contain 368 the node or link properties. A unique PCEP specific LS identifier 369 (LS-ID) is also carried in the message to identify a node or link and 370 that remains constant for the lifetime of a PCEP session. This 371 identifier on its own is sufficient when no IGP or BGP-LS running in 372 the network for PCE to learn link-state (and TE) information. In 373 case PCE learns some information from PCEP and some from the existing 374 mechanism, the PCC SHOULD include the mapping of IGP or BGP-LS 375 identifier to map the information populated via PCEP with IGP/BGP-LS. 376 See Section 8.1 for details. 378 6.2. Capability Advertisement 380 During PCEP Initialization Phase, PCEP Speakers (PCE or PCC) 381 advertise their support of LS (and TE) distribution via PCEP 382 extensions. A PCEP Speaker includes the "LS Capability" TLV, 383 described in Section 9.2.1, in the OPEN Object to advertise its 384 support for PCEP-LS extensions. The presence of the LS Capability 385 TLV in PCC's OPEN Object indicates that the PCC is willing to send LS 386 Reports with local link-state (and TE) information. The presence of 387 the LS Capability TLV in PCE's Open message indicates that the PCE is 388 interested in receiving LS Reports with local link-state (and TE) 389 information. 391 The PCEP extensions for LS (and TE) distribution MUST NOT be used if 392 one or both PCEP Speakers have not included the LS Capability TLV in 393 their respective OPEN message. If the PCE that supports the 394 extensions of this draft but did not advertise this capability, then 395 upon receipt of an LSRpt message from the PCC, it SHOULD generate a 396 PCErr with error-type 19 (Invalid Operation), error-value TBD1 397 (Attempted LS Report if LS capability was not advertised) and it will 398 terminate the PCEP session. 400 The LS reports sent by PCC MAY carry the remote link-state (and TE) 401 information learned via existing means like IGP and BGP-LS only if 402 both PCEP Speakers set the R (remote) Flag in the "LS Capability" TLV 403 to 'Remote Allowed (R Flag = 1)'. If this is not the case and LS 404 reports carry remote link-state (and TE) information, then a PCErr 405 with error-type 19 (Invalid Operation) and error-value TBD1 406 (Attempted LS Report if LS remote capability was not advertised) and 407 it will terminate the PCEP session. 409 6.3. Initial Link-State (and TE) Synchronization 411 The purpose of LS Synchronization is to provide a checkpoint-in-time 412 state replica of a PCC's link-state (and TE) database in a PCE. 413 State Synchronization is performed immediately after the 414 Initialization phase (see [RFC5440]). In case of stateful PCE 415 ([RFC8231]) it is RECOMMENDED that the LS synchronization should be 416 done before LSP state synchronization. 418 During LS Synchronization, a PCC first takes a snapshot of the state 419 of its database, then sends the snapshot to a PCE in a sequence of LS 420 Reports. Each LS Report sent during LS Synchronization has the SYNC 421 Flag in the LS Object set to 1. The end of synchronization marker is 422 an LSRpt message with the SYNC Flag set to 0 for an LS Object with 423 LS-ID equal to the reserved value 0. If the PCC has no link-state to 424 synchronize, it will only send the end of synchronization marker. 426 Either the PCE or the PCC MAY terminate the session using the PCEP 427 session termination procedures during the synchronization phase. If 428 the session is terminated, the PCE MUST clean up the state it 429 received from this PCC. The session re-establishment MUST be re- 430 attempted per the procedures defined in [RFC5440], including the use 431 of a back-off timer. 433 If the PCC encounters a problem which prevents it from completing the 434 LS synchronization, it MUST send a PCErr message with error-type TBD2 435 (LS Synchronization Error) and error-value 2 (indicating an internal 436 PCC error) to the PCE and terminate the session. 438 The PCE does not send positive acknowledgments for properly received 439 LS synchronization messages. It MUST respond with a PCErr message 440 with error-type TBD2 (LS Synchronization Error) and error-value 1 441 (indicating an error in processing the LSRpt) if it encounters a 442 problem with the LS Report it received from the PCC and it MUST 443 terminate the session. 445 The LS reports can carry local as well as remote link-state (and TE) 446 information depending on the R flag in LS capability TLV. 448 The successful LS Synchronization sequence is shown in Figure 1. 450 +-+-+ +-+-+ 451 |PCC| |PCE| 452 +-+-+ +-+-+ 453 | | 454 |-----LSRpt, SYNC=1----->| (Sync start) 455 | | 456 |-----LSRpt, SYNC=1----->| 457 | . | 458 | . | 459 | . | 460 |-----LSRpt, SYNC=1----->| 461 | . | 462 | . | 463 | . | 464 | | 465 |-----LSRpt, SYNC=0----->| (End of sync marker 466 | | LS Report 467 | | for LS-ID=0) 468 | | (Sync done) 470 Figure 1: Successful LS synchronization 472 The sequence where the PCE fails during the LS Synchronization phase 473 is shown in Figure 2. 475 +-+-+ +-+-+ 476 |PCC| |PCE| 477 +-+-+ +-+-+ 478 | | 479 |-----LSRpt, SYNC=1----->| 480 | | 481 |-----LSRpt, SYNC=1----->| 482 | . | 483 | . | 484 | . | 485 |-----LSRpt, SYNC=1----->| 486 | | 487 |---LSRpt,SYNC=1 | 488 | \ ,-PCErr---| 489 | \ / | 490 | \/ | 491 | /\ | 492 | / `-------->| (Ignored) 493 |<--------` | 495 Figure 2: Failed LS synchronization (PCE failure) 497 The sequence where the PCC fails during the LS Synchronization phase 498 is shown in Figure 3. 500 +-+-+ +-+-+ 501 |PCC| |PCE| 502 +-+-+ +-+-+ 503 | | 504 |-----LSRpt, SYNC=1----->| 505 | | 506 |-----LSRpt, SYNC=1----->| 507 | . | 508 | . | 509 | . | 510 |-------- PCErr--------->| 511 | | 513 Figure 3: Failed LS synchronization (PCC failure) 515 6.3.1. Optimizations for LS Synchronization 517 These optimizations are described in 518 [I-D.kondreddy-pce-pcep-ls-sync-optimizations]. 520 6.4. LS Report 522 The PCC MUST report any changes in the link-state (and TE) 523 information to the PCE by sending an LS Report carried on an LSRpt 524 message to the PCE. Each node and Link would be uniquely identified 525 by a PCEP LS identifier (LS-ID). The LS reports may carry local as 526 well as remote link-state (and TE) information depending on the R 527 flag in LS capability TLV. It MAY also include the mapping of IGP or 528 BGP-LS identifier to map the information populated via PCEP with IGP/ 529 BGP-LS identifiers. 531 More details about the LSRpt message are in Section 8.1. 533 7. Transport 535 A permanent PCEP session (section 4.2.8 of [RFC5440]) MUST be 536 established between a PCE and PCC supporting link-state (and TE) 537 distribution via PCEP. In the case of session failure, session re- 538 establishment is re-attempted as per the procedures defined in 539 [RFC5440]. 541 8. PCEP Messages 543 As defined in [RFC5440], a PCEP message consists of a common header 544 followed by a variable-length body made of a set of objects that can 545 be either mandatory or optional. An object is said to be mandatory 546 in a PCEP message when the object must be included for the message to 547 be considered valid. For each PCEP message type, a set of rules is 548 defined that specify the set of objects that the message can carry. 549 An implementation MUST form the PCEP messages using the object 550 ordering specified in this document. 552 8.1. LS Report Message 554 A PCEP LS Report message (also referred to as LSRpt message) is a 555 PCEP message sent by a PCC to a PCE to report the link-state (and TE) 556 information. An LSRpt message can carry more than one LS Reports (LS 557 object). The Message-Type field of the PCEP common header for the 558 LSRpt message is set to [TBD3]. 560 The format of the LSRpt message is as follows: 562 ::= 563 564 Where: 566 ::= [] 567 The LS object is a mandatory object which carries LS information of a 568 node/prefix or a link. Each LS object has a unique LS-ID as 569 described in Section 9.3. If the LS object is missing, the receiving 570 PCE MUST send a PCErr message with Error-type=6 (Mandatory Object 571 missing) and Error-value=[TBD4] (LS object missing). 573 A PCE may choose to implement a limit on the LS information a single 574 PCC can populate. If an LSRpt is received that causes the PCE to 575 exceed this limit, it MUST send a PCErr message with error-type 19 576 (invalid operation) and error-value 4 (indicating resource limit 577 exceeded) in response to the LSRpt message triggering this condition 578 and SHOULD terminate the session. 580 8.2. The PCErr Message 582 If a PCEP speaker has advertised the LS capability on the PCEP 583 session, the PCErr message MAY include the LS object. If the error 584 reported is the result of an LS report, then the LS-ID number MUST be 585 the one from the LSRpt that triggered the error. 587 The format of a PCErr message from [RFC5440] is extended as follows: 589 ::= 590 ( [] ) | 591 [] 593 ::=[] 595 ::=[ | ] 596 598 ::=[] 600 ::=[] 602 ::=[] 604 9. Objects and TLV 606 The PCEP objects defined in this document are compliant with the PCEP 607 object format defined in [RFC5440]. The P flag and the I flag of the 608 PCEP objects defined in this document MUST always be set to 0 on 609 transmission and MUST be ignored on receipt since these flags are 610 exclusively related to path computation requests. 612 9.1. TLV Format 614 The TLV and the sub-TLV format (and padding) in this document, is as 615 per section 7.1 of [RFC5440]. 617 9.2. Open Object 619 This document defines a new optional TLV for use in the OPEN Object. 621 9.2.1. LS Capability TLV 623 The LS-CAPABILITY TLV is an optional TLV for use in the OPEN Object 624 for link-state (and TE) distribution via PCEP capability 625 advertisement. Its format is shown in the following figure: 627 0 1 2 3 628 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 1 629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 | Type=[TBD5] | Length=4 | 631 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 | Flags |R| 633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 635 The type of the TLV is [TBD5] and it has a fixed length of 4 octets. 637 The value comprises a single field - Flags (32 bits): 639 o R (remote allowed - 1 bit): if set to 1 by a PCC, the R Flag 640 indicates that the PCC allows reporting of remote LS information 641 learned via other means like IGP and BGP-LS; if set to 1 by a PCE, 642 the R Flag indicates that the PCE is capable of receiving remote 643 LS information (from the PCC point of view). The R Flag must be 644 advertised by both PCC and PCE for LSRpt messages to report remote 645 as well as local LS information on a PCEP session. The TLVs 646 related to IGP/BGP-LS identifier MUST be encoded when both PCEP 647 speakers have the R Flag set. 649 Unassigned bits are considered reserved. They MUST be set to 0 on 650 transmission and MUST be ignored on receipt. 652 Advertisement of the LS capability implies support of local link- 653 state (and TE) distribution, as well as the objects, TLVs and 654 procedures defined in this document. 656 9.3. LS Object 658 The LS (link-state) object MUST be carried within LSRpt messages and 659 MAY be carried within PCErr messages. The LS object contains a set 660 of fields used to specify the target node or link. It also contains 661 a flag indicating to a PCE that the LS synchronization is in 662 progress. The TLVs used with the LS object correlate with the IGP/ 663 BGP-LS encodings. 665 LS Object-Class is TBD6. 667 Four Object-Type values are defined for the LS object so far: 669 o LS Node: LS Object-Type is 1. 671 o LS Link: LS Object-Type is 2. 673 o LS IPv4 Topology Prefix: LS Object-Type is 3. 675 o LS IPv6 Topology Prefix: LS Object-Type is 4. 677 The format of all types of LS object is as follows: 679 0 1 2 3 680 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 1 681 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 682 | Protocol-ID | Flag |R|S| 683 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 684 | LS-ID | 685 | | 686 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 687 // TLVs // 688 | | 689 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 691 Protocol-ID (8-bit): The field provides the source information. The 692 protocol could be an IGP, BGP-LS, or an abstraction algorithm. In 693 case PCC only provides local information of the PCC, it MUST use 694 Protocol-ID as Direct. The following values are defined (some of the 695 initial values are the same as [I-D.ietf-idr-rfc7752bis]): 697 +-------------+----------------------------------+ 698 | Protocol-ID | Source protocol | 699 +-------------+----------------------------------+ 700 | 1 | IS-IS Level 1 | 701 | 2 | IS-IS Level 2 | 702 | 3 | OSPFv2 | 703 | 4 | Direct | 704 | 5 | Static configuration | 705 | 6 | OSPFv3 | 706 | 7 | BGP | 707 | 8 | RSVP-TE | 708 | 9 | Segment Routing | 709 | 10 | PCEP | 710 | 11 | Abstraction | 711 +-------------+----------------------------------+ 713 Flags (24-bit): 715 o S (SYNC - 1 bit): the S Flag MUST be set to 1 on each LSRpt sent 716 from a PCC during LS Synchronization. The S Flag MUST be set to 0 717 in other LSRpt messages sent from the PCC. 719 o R (Remove - 1 bit): On LSRpt messages, the R Flag indicates that 720 the node/link/prefix has been removed from the PCC and the PCE 721 SHOULD remove from its database. Upon receiving an LS Report with 722 the R Flag set to 1, the PCE SHOULD remove all state for the 723 node/link/prefix identified by the LS Identifiers from its 724 database. 726 LS-ID(64-bit): A PCEP-specific identifier for the node, link, or 727 prefix information. A PCC creates a unique LS-ID for each node/link/ 728 prefix that is constant for the lifetime of a PCEP session. The PCC 729 will advertise the same LS-ID on all PCEP sessions it maintains at a 730 given time. All subsequent PCEP messages then address the node/link/ 731 prefix by the LS-ID. The values of 0 and 0xFFFFFFFFFFFFFFFF are 732 reserved. 734 Unassigned bits are considered reserved. They MUST be set to 0 on 735 transmission and MUST be ignored on receipt. 737 TLVs that may be included in the LS Object are described in the 738 following sections. 740 9.3.1. Routing Universe TLV 742 In the case of remote link-state (and TE) population when existing 743 IGP/BGP-LS are also used, OSPF and IS-IS may run multiple routing 744 protocol instances over the same link as described in 746 [I-D.ietf-idr-rfc7752bis]. See [RFC8202] and [RFC6549] for more 747 information. These instances define an independent "routing 748 universe". The 64-bit 'Identifier' field is used to identify the 749 "routing universe" where the LS object belongs. The LS objects 750 representing IGP objects (nodes or links or prefix) from the same 751 routing universe MUST have the same 'Identifier' value; LS objects 752 with different 'Identifier' values MUST be considered to be from 753 different routing universes. 755 The format of the optional ROUTING-UNIVERSE TLV is shown in the 756 following figure: 758 0 1 2 3 759 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 1 760 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 761 | Type=[TBD7] | Length=8 | 762 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 763 | Identifier | 764 | | 765 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 767 The below table lists the 'Identifier' values that are defined as 768 well-known in this draft (same as [I-D.ietf-idr-rfc7752bis]). 770 +------------+-----------------------------------+ 771 | Identifier | Routing Universe | 772 +------------+-----------------------------------+ 773 | 0 | Default Layer 3 Routing topology | 774 +------------+-----------------------------------+ 776 If this TLV is not present the default value 0 is assumed. 778 9.3.2. Route Distinguisher TLV 780 To allow identification of VPN link, node, and prefix information in 781 PCEP-LS, a Route Distinguisher (RD) [RFC4364] is used. The LS 782 objects from the same VPN MUST have the same RD; LS objects with 783 different RD values MUST be considered to be from different VPNs. 785 The ROUTE-DISTINGUISHER TLV is defined in 786 [I-D.ietf-pce-pcep-flowspec] as a Flow Specification TLVs with a 787 seperate registry. This document also adds the ROUTE-DISTINGUISHER 788 TLV with TBD15 in the PCEP TLV registry to be used inside the LS 789 object. 791 9.3.3. Virtual Network TLV 793 To realize ACTN, the MDSC needs to build a multi-domain topology. 794 This topology is best served if this is an abstracted view of the 795 underlying network resources of each domain. It is also important to 796 provide a customer view of the network slice for each customer. 797 There is a need to control the level of abstraction based on the 798 deployment scenario and business relationship between the 799 controllers. 801 Virtual service coordination function in ACTN incorporates customer 802 service-related knowledge into the virtual network operations in 803 order to seamlessly operate virtual networks while meeting customer's 804 service requirements. [I-D.ietf-teas-actn-requirements] describes 805 various VN operations initiated by a customer/application. In this 806 context, there is a need for associating the abstracted link-state 807 and TE topology with a VN "construct" to facilitate VN operations in 808 PCE architecture. 810 VIRTUAL-NETWORK-TLV as per [I-D.ietf-pce-vn-association] can be 811 included in LS object to identify the link, node, and prefix 812 information belongs to a particular VN. 814 9.3.4. Local Node Descriptors TLV 816 As described in [I-D.ietf-idr-rfc7752bis], each link is anchored by a 817 pair of Router-IDs that are used by the underlying IGP, namely, 818 48-bit ISO System-ID for IS-IS and 32-bit Router-ID for OSPFv2 and 819 OSPFv3. In case of additional auxiliary Router-IDs used for TE, 820 these MUST also be included in the link attribute TLV (see 821 Section 9.3.9.2). 823 It is desirable that the Router-ID assignments inside the Node 824 Descriptors TLV are globally unique. Some considerations for 825 globally unique Node/Link/Prefix identifiers are described in 826 [I-D.ietf-idr-rfc7752bis]. 828 The Local Node Descriptors TLV contains Node Descriptors for the node 829 anchoring the local end of the link. This TLV MUST be included in 830 the LS Report when during a given PCEP session a node/link/prefix is 831 first reported to a PCE. A PCC sends to a PCE the first LS Report 832 either during State Synchronization, or when a new node/link/prefix 833 is learned at the PCC. The value contains one or more Node 834 Descriptor Sub-TLVs, which allows the specification of a flexible key 835 for any given node/link/prefix information such that the global 836 uniqueness of the node/link/prefix is ensured. 838 This TLV is applicable for all LS Object-Type. 840 0 1 2 3 841 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 1 842 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 843 | Type=[TBD8] | Length | 844 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 845 | | 846 // Node Descriptor Sub-TLVs (variable) // 847 | | 848 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 850 The value contains one or more Node Descriptor Sub-TLVs defined in 851 Section 9.3.6. 853 9.3.5. Remote Node Descriptors TLV 855 The Remote Node Descriptors contain Node Descriptors for the node 856 anchoring the remote end of the link. This TLV MUST be included in 857 the LS Report when during a given PCEP session a link is first 858 reported to a PCE. A PCC sends to a PCE the first LS Report either 859 during State Synchronization, or when a new link is learned at the 860 PCC. The length of this TLV is variable. The value contains one or 861 more Node Descriptor Sub-TLVs defined in Section 9.3.6. 863 This TLV is applicable for LS Link Object-Type. 865 0 1 2 3 866 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 1 867 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 868 | Type=[TBD9] | Length | 869 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 870 | | 871 // Node Descriptor Sub-TLVs (variable) // 872 | | 873 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 875 9.3.6. Node Descriptors Sub-TLVs 877 The Node Descriptors TLV (Local and Remote) carries one or more Node 878 Descriptor Sub-TLV follows the format of all PCEP TLVs as defined in 879 [RFC5440], however, the Type values are selected from a new PCEP-LS 880 sub-TLV IANA registry (see Section 13.6). 882 Type values are chosen so that there can be commonality with BGP-LS 883 [I-D.ietf-idr-rfc7752bis]. This is possible because the "BGP-LS Node 884 Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs" 885 registry marks 0-255 as reserved. Thus the space of the sub-TLV 886 values for the Type field can be partitioned as shown below - 887 Range | 888 ---------------+--------------------------------------------- 889 0 | Reserved - must not be allocated. 890 | 891 1 .. 255 | New PCEP sub-TLV allocated according to the 892 | registry defined in this document. 893 | 894 256 .. 65535 | Per BGP registry defined by 895 | [I-D.ietf-idr-rfc7752bis]. 896 | Not to be allocated in this registry. 898 All Node Descriptors TLVs defined for BGP-LS can then be used with 899 PCEP-LS as well. One new PCEP sub-TLVs for Node Descriptor are 900 defined in this document. 902 +----------+-------------------+----------+----------------+ 903 | Sub-TLV | Description | Length |Value defined in| 904 +----------+-------------------+----------+----------------+ 905 | 1 | SPEAKER-ENTITY-ID | Variable | [RFC8232] | 906 +----------+-------------------+----------+----------------+ 908 A new sub-TLV type (1) is allocated for SPEAKER-ENTITY-ID sub-TLV. 909 The length and value fields are as per [RFC8232]. 911 9.3.7. Link Descriptors TLV 913 The Link Descriptors TLV contains Link Descriptors for each link. 914 This TLV MUST be included in the LS Report when during a given PCEP 915 session a link is first reported to a PCE. A PCC sends to a PCE the 916 first LS Report either during State Synchronization, or when a new 917 link is learned at the PCC. The length of this TLV is variable. The 918 value contains one or more Link Descriptor Sub-TLVs. 920 The 'Link descriptor' TLVs uniquely identify a link among multiple 921 parallel links between a pair of anchor routers similar to 922 [I-D.ietf-idr-rfc7752bis]. 924 This TLV is applicable for LS Link Object-Type. 926 0 1 2 3 927 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 1 928 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 929 | Type=[TBD10] | Length | 930 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 931 | | 932 // Link Descriptor Sub-TLVs (variable) // 933 | | 934 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 936 All Link Descriptors TLVs defined for BGP-LS can then be used with 937 PCEP-LS as well. No new PCEP sub-TLVs for Link Descriptor are 938 defined in this document. 940 The format and semantics of the 'value' fields in most 'Link 941 Descriptor' sub-TLVs correspond to the format and semantics of value 942 fields in IS-IS Extended IS Reachability sub-TLVs, defined in 943 [RFC5305], [RFC5307] and [RFC6119]. Although the encodings for 'Link 944 Descriptor' TLVs were originally defined for IS-IS, the TLVs can 945 carry data sourced either by IS-IS or OSPF or direct. 947 The information about a link present in the LSA/LSP originated by the 948 local node of the link determines the set of sub-TLVs in the Link 949 Descriptor of the link as described in [I-D.ietf-idr-rfc7752bis]. 951 9.3.8. Prefix Descriptors TLV 953 The Prefix Descriptors TLV contains Prefix Descriptors that uniquely 954 identify an IPv4 or IPv6 Prefix originated by a Node. This TLV MUST 955 be included in the LS Report when during a given PCEP session a 956 prefix is first reported to a PCE. A PCC sends to a PCE the first LS 957 Report either during State Synchronization, or when a new prefix is 958 learned at the PCC. The length of this TLV is variable. 960 This TLV is applicable for LS Prefix Object-Types for both IPv4 and 961 IPv6. 963 0 1 2 3 964 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 1 965 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 966 | Type=[TBD11] | Length | 967 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 968 | | 969 // Prefix Descriptor Sub-TLVs (variable) // 970 | | 971 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 973 All Prefix Descriptors TLVs defined for BGP-LS can then be used with 974 PCEP-LS as well. No new PCEP sub-TLVs for Prefix Descriptor are 975 defined in this document. 977 9.3.9. PCEP-LS Attributes 979 9.3.9.1. Node Attributes TLV 981 This is an optional attribute that is used to carry node attributes. 982 This TLV is applicable for LS Node Object-Type. 984 0 1 2 3 985 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 1 986 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 987 | Type=[TBD12] | Length | 988 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 989 | | 990 // Node Attributes Sub-TLVs (variable) // 991 | | 992 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 994 All Node Attributes TLVs defined for BGP-LS can then be used with 995 PCEP-LS as well. No new PCEP sub-TLVs for Node Attributes are 996 defined in this document. 998 9.3.9.2. Link Attributes TLV 1000 This TLV is applicable for LS Link Object-Type. The format and 1001 semantics of the 'value' fields in some 'Link Attribute' sub-TLVs 1002 correspond to the format and semantics of the 'value' fields in IS-IS 1003 Extended IS Reachability sub-TLVs, defined in [RFC5305], [RFC5307] 1004 and [I-D.ietf-idr-rfc7752bis]. Although the encodings for 'Link 1005 Attribute' TLVs were originally defined for IS-IS, the TLVs can carry 1006 data sourced either by IS-IS or OSPF or direct. 1008 0 1 2 3 1009 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 1010 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1011 | Type=[TBD13] | Length | 1012 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1013 | | 1014 // Link Attributes Sub-TLVs (variable) // 1015 | | 1016 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1018 All Link Attributes TLVs defined for BGP-LS can then be used with 1019 PCEP-LS as well. No new PCEP sub-TLVs for Link Attributes are 1020 defined in this document. 1022 9.3.9.3. Prefix Attributes TLV 1024 This TLV is applicable for LS Prefix Object-Types for both IPv4 and 1025 IPv6. Prefixes are learned from the IGP (IS-IS or OSPF) or BGP 1026 topology with a set of IGP attributes (such as metric, route tags, 1027 etc.). This section describes the different attributes related to 1028 the IPv4/IPv6 prefixes. Prefix Attributes TLVs SHOULD be encoded in 1029 the LS Prefix Object. 1031 0 1 2 3 1032 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 1033 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1034 | Type=[TBD14] | Length | 1035 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1036 | | 1037 // Prefix Attributes Sub-TLVs (variable) // 1038 | | 1039 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1041 All Prefix Attributes TLVs defined for BGP-LS can then be used with 1042 PCEP-LS as well. No new PCEP sub-TLVs for Prefix Attributes are 1043 defined in this document. 1045 9.3.10. Removal of an Attribute 1047 One of the key objectives of PCEP-LS is to encode and carry only the 1048 impacted attributes of a Node, a Link, or a Prefix. To accommodate 1049 this requirement, in case of a removal of an attribute, the sub-TLV 1050 MUST be included with no 'value' field and length=0 to indicate that 1051 the attribute is removed. On receiving a sub-TLV with zero length, 1052 the receiver removes the attribute from the database. An absence of 1053 a sub-TLV that was included earlier MUST be interpreted as no change. 1055 10. Other Considerations 1057 10.1. Inter-AS Links 1059 The main source of LS (and TE) information is the IGP, which is not 1060 active on inter-AS links. In some cases, the IGP may have 1061 information of inter-AS links ([RFC5392], [RFC5316]). In other 1062 cases, an implementation SHOULD provide a means to inject inter-AS 1063 links into PCEP. The exact mechanism used to provision the inter-AS 1064 links is outside the scope of this document. 1066 11. Security Considerations 1068 This document extends PCEP for LS (and TE) distribution including a 1069 new LSRpt message with a new object and TLVs. Procedures and 1070 protocol extensions defined in this document do not effect the 1071 overall PCEP security model. See [RFC5440], [RFC8253]. Tampering 1072 with the LSRpt message may have an effect on path computations at 1073 PCE. It also provides adversaries an opportunity to eavesdrop and 1074 learn sensitive information and plan sophisticated attacks on the 1075 network infrastructure. The PCE implementation SHOULD provide 1076 mechanisms to prevent strains created by network flaps and amount of 1077 LS (and TE) information. Thus it is suggested that any mechanism 1078 used for securing the transmission of other PCEP message be applied 1079 here as well. As a general precaution, it is RECOMMENDED that these 1080 PCEP extensions only are activated on authenticated and encrypted 1081 sessions belonging to the same administrative authority. 1083 Further, as stated in [RFC6952], PCEP implementations SHOULD support 1084 the TCP-AO [RFC5925] and not use TCP MD5 because of TCP MD5's known 1085 vulnerabilities and weaknesses. PCEP also support Transport Layer 1086 Security (TLS) [RFC8253] as per the recommendations and best current 1087 practices in [RFC7525]. 1089 12. Manageability Considerations 1091 All manageability requirements and considerations listed in [RFC5440] 1092 apply to PCEP protocol extensions defined in this document. In 1093 addition, requirements, and considerations listed in this section 1094 apply. 1096 12.1. Control of Function and Policy 1098 A PCE or PCC implementation MUST allow configuring the PCEP-LS 1099 capabilities as described in this document. 1101 A PCC implementation SHOULD allow configuration to suggest if remote 1102 information learned via routing protocols should be reported or not. 1104 An implementation SHOULD allow the operator to specify the maximum 1105 number of LS data to be reported. 1107 An implementation SHOULD also allow the operator to create abstracted 1108 topologies that are reported to the peers and create different 1109 abstractions for different peers. 1111 An implementation SHOULD allow the operator to configure a 64-bit 1112 identifier for Routing Universe TLV. 1114 12.2. Information and Data Models 1116 An implementation SHOULD allow the operator to view the LS 1117 capabilities advertised by each peer. To serve this purpose, the 1118 PCEP YANG module [I-D.ietf-pce-pcep-yang] can be extended to include 1119 advertised capabilities. 1121 An implementation SHOULD also provide the statistics: 1123 o Total number of LSRpt sent/received, as well as per neighbour 1125 o Number of errors received for LSRpt, per neighbour 1126 o Total number of locally originated Link-State Information 1128 These statistics should be recorded as absolute counts since system 1129 or session start time. An implementation MAY also enhance this 1130 information by recording peak per-second counts in each case. 1132 An operator SHOULD define an import policy to limit inbound LSRpt to 1133 "drop all LSRpt from a particular peer" as well provide means to 1134 limit inbound LSRpts. 1136 12.3. Liveness Detection and Monitoring 1138 Mechanisms defined in this document do not imply any new liveness 1139 detection and monitoring requirements in addition to those already 1140 listed in [RFC5440]". 1142 12.4. Verify Correct Operations 1144 Mechanisms defined in this document do not imply any new operation 1145 verification requirements in addition to those already listed in 1146 [RFC5440] . 1148 12.5. Requirements On Other Protocols 1150 Mechanisms defined in this document do not imply any new requirements 1151 on other protocols. 1153 12.6. Impact On Network Operations 1155 Mechanisms defined in this document do not have any impact on network 1156 operations in addition to those already listed in [RFC5440]. 1158 13. IANA Considerations 1160 This document requests IANA actions to allocate code points for the 1161 protocol elements defined in this document. 1163 13.1. PCEP Messages 1165 IANA created a registry for "PCEP Messages". Each PCEP message has a 1166 message type value. This document defines a new PCEP message value. 1168 Value Meaning Reference 1169 TBD3 LSRpt [This I-D] 1171 13.2. PCEP Objects 1173 This document defines the following new PCEP Object-classes and 1174 Object-values: 1176 Object-Class Value Name Reference 1177 TBD6 LS Object [This I-D] 1178 Object-Type=1 1179 (LS Node) 1180 Object-Type=2 1181 (LS Link) 1182 Object-Type=3 1183 (LS IPv4 Prefix) 1184 Object-Type=4 1185 (LS IPv6 Prefix) 1187 13.3. LS Object 1189 This document requests that a new sub-registry, named "LS Object 1190 Protocol-ID Field", is created within the "Path Computation Element 1191 Protocol (PCEP) Numbers" registry to manage the Flag field of the LSP 1192 object. New values are to be assigned by Standards Action [RFC8126]. 1194 Value Meaning Reference 1195 0 Reserved [This I-D] 1196 1 IS-IS Level 1 [This I-D] 1197 2 IS-IS Level 2 [This I-D] 1198 3 OSPFv2 [This I-D] 1199 4 Direct [This I-D] 1200 5 Static configuration [This I-D] 1201 6 OSPFv3 [This I-D] 1202 7 BGP [This I-D] 1203 8 RSVP-TE [This I-D] 1204 9 Segment Routing [This I-D] 1205 10 PCEP [This I-D] 1206 11 Abstraction [This I-D] 1207 12-255 Unassigned 1209 Further, this document also requests that a new sub-registry, named 1210 "LS Object Flag Field", is created within the "Path Computation 1211 Element Protocol (PCEP) Numbers" registry to manage the Flag field of 1212 the LSP object.New values are to be assigned by Standards Action 1213 [RFC8126]. Each bit should be tracked with the following qualities: 1215 o Bit number (counting from bit 0 as the most significant bit) 1217 o Capability description 1218 o Defining RFC 1220 The following values are defined in this document: 1222 Bit Description Reference 1223 0-21 Unassigned 1224 22 R (Remove bit) [This I-D] 1225 23 S (Sync bit) [This I-D] 1227 13.4. PCEP-Error Object 1229 IANA is requested to make the following allocation in the "PCEP-ERROR 1230 Object Error Types and Values" registry. 1232 Error-Type Meaning Reference 1233 6 Mandatory Object missing [RFC5440] 1234 Error-Value=TBD4 [This I-D] 1235 (LS object missing) 1237 19 Invalid Operation [RFC8231] 1238 Error-Value=TBD1 [This I-D] 1239 (Attempted LS Report if LS 1240 remote capability was not 1241 advertised) 1243 TBD2 LS Synchronization Error [This I-D] 1244 Error-Value=1 1245 (An error in processing the 1246 LSRpt) 1247 Error-Value=2 1248 (An internal PCC error) 1250 13.5. PCEP TLV Type Indicators 1252 This document defines the following new PCEP TLVs. 1254 Value Meaning Reference 1255 TBD5 LS-CAPABILITY TLV [This I-D] 1256 TBD7 ROUTING-UNIVERSE TLV [This I-D] 1257 TBD15 ROUTE-DISTINGUISHER TLV [This I-D] 1258 TBD8 Local Node Descriptors TLV [This I-D] 1259 TBD9 Remote Node Descriptors TLV [This I-D] 1260 TBD10 Link Descriptors TLV [This I-D] 1261 TBD11 Prefix Descriptors TLV [This I-D] 1262 TBD12 Node Attributes TLV [This I-D] 1263 TBD13 Link Attributes TLV [This I-D] 1264 TBD14 Prefix Attributes TLV [This I-D] 1266 13.6. PCEP-LS Sub-TLV Type Indicators 1268 This document specifies the PCEP-LS Sub-TLVs. IANA is requested to 1269 create an "PCEP-LS Sub-TLV Types" sub-registry for the sub-TLVs 1270 carried in the PCEP-LS TLV (Local and Remote Node Descriptors TLV, 1271 Link Descriptors TLV, Prefix Descriptors TLV, Node Attributes TLV, 1272 Link Attributes TLV and Prefix Attributes TLV. 1274 Allocations from this registry are to be made according to the 1275 following assignment policies [RFC8126]: 1277 Range | Assignment policy 1278 ---------------+--------------------------------------------------- 1279 0 | Reserved - must not be allocated. 1280 | 1281 1 .. 251 | Specification Required 1282 | 1283 252 .. 255 | Experimental Use 1284 | 1285 256 .. 65535 | Reserved - must not be allocated. 1286 | Usage mirrors the BGP-LS TLV registry 1287 | [I-D.ietf-idr-rfc7752bis] 1288 | 1290 IANA is requested to pre-populate this registry with values defined 1291 in this document as follows, taking the new values from the range 1 1292 to 251: 1294 Value | Meaning 1295 -------+------------------------ 1296 1 | SPEAKER-ENTITY-ID 1298 14. TLV Code Points Summary 1300 This section contains the global table of all TLVs in LS object 1301 defined in this document. 1303 +-----------+---------------------+---------------+-----------------+ 1304 | TLV | Description | Ref TLV | Value defined | 1305 | | | | in: | 1306 +-----------+---------------------+---------------+-----------------+ 1307 | TBD7 | Routing Universe | -- | Sec 9.2.1 | 1308 | TBD15 | Route | -- | Sec 9.2.2 | 1309 | | Distinguisher | | | 1310 | * | Virtual Network | -- | [ietf-pce- | 1311 | | | | vn-association] | 1312 | TBD8 | Local Node | 256 | [I-D.ietf-idr- | 1313 | | | | rfc7752bis] | 1314 | | Descriptors | | /3.2.1.2 | 1315 | TBD9 | Remote Node | 257 | [I-D.ietf-idr- | 1316 | | | | rfc7752bis] | 1317 | | Descriptors | | /3.2.1.3 | 1318 | TBD10 | Link Descriptors | -- | Sec 9.2.8 | 1319 | TBD11 | Prefix Descriptors | -- | Sec 9.2.9 | 1320 | TBD12 | Node Attributes | -- | Sec 9.2.10.1 | 1321 | TBD13 | Link Attributes | -- | Sec 9.2.10.2 | 1322 | TBD14 | Prefix Attributes | -- | Sec 9.2.10.3 | 1323 +-----------+---------------------+---------------+-----------------+ 1325 * this TLV is defined in a different PCEP document 1327 TLV Table 1329 15. Implementation Status 1331 The PCEP-LS protocol extensions as described in this I-D were 1332 implemented and tested for a variety of applications. Apart from the 1333 below implementation, there exist other experimental implementations 1334 done for optical networks. 1336 15.1. Hierarchical Transport PCE controllers 1338 The PCEP-LS has been implemented as part of IETF97 Hackathon and 1339 Bits-N-Bites demonstration. The use-case demonstrated was DCI use- 1340 case of ACTN architecture in which to show the following scenarios: 1342 - connectivity services on the ACTN based recursive hierarchical 1343 SDN/PCE platform that has the three-tier level SDN controllers 1344 (two-tier level MDSC and PNC) on the top of the PTN systems 1345 managed by EMS. 1347 - Integration test of two tier-level MDSC: The SBI of the low 1348 level MDSC is the YANG based Korean national standards and the one 1349 of the high-level MDSC the PCEP-LS based ACTN protocols. 1351 - Performance test of three types of SDN controller based recovery 1352 schemes including protection, reactive, and proactive restoration. 1353 PCEP-LS protocol was used to demonstrate a quick report of failed 1354 network components. 1356 15.2. ONOS-based Controller (MDSC and PNC) 1358 Huawei (PNC, MDSC) and SKT (MDSC) implemented PCEP-LS during 1359 Hackathon and IETF97 Bits-N-Bites demonstration. The demonstration 1360 was ONOS-based ACTN architecture in which to show the following 1361 capabilities: 1363 Both packet PNC and optical PNC (with optical PCEP-LS extensions) 1364 implemented PCEP-LS on its SBI as well as its NBI (towards MDSC). 1366 SKT orchestrator (acting as MDSC) also supported PCEP-LS (as well 1367 as RestConf) towards packet and optical PNCs on its SBI. 1369 Further description can be found at and the code at 1370 . 1372 16. Acknowledgments 1374 This document borrows some of the structure and text from the 1375 [I-D.ietf-idr-rfc7752bis]. 1377 Thanks to Eric Wu, Venugopal Kondreddy, Mahendra Singh Negi, 1378 Avantika, and Zhengbin Li for the reviews. 1380 Thanks to Ramon Casellas for his comments and suggestions based on 1381 his implementation experience. 1383 17. References 1385 17.1. Normative References 1387 [I-D.ietf-idr-rfc7752bis] 1388 Talaulikar, K., "Distribution of Link-State and Traffic 1389 Engineering Information Using BGP", draft-ietf-idr- 1390 rfc7752bis-05 (work in progress), November 2020. 1392 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1393 Requirement Levels", BCP 14, RFC 2119, 1394 DOI 10.17487/RFC2119, March 1997, 1395 . 1397 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 1398 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 1399 2008, . 1401 [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions 1402 in Support of Generalized Multi-Protocol Label Switching 1403 (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, 1404 . 1406 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 1407 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 1408 DOI 10.17487/RFC5440, March 2009, 1409 . 1411 [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic 1412 Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119, 1413 February 2011, . 1415 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1416 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1417 May 2017, . 1419 [RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 1420 and D. Dhody, "Optimizations of Label Switched Path State 1421 Synchronization Procedures for a Stateful PCE", RFC 8232, 1422 DOI 10.17487/RFC8232, September 2017, 1423 . 1425 17.2. Informative References 1427 [I-D.ietf-pce-pcep-flowspec] 1428 Dhody, D., Farrel, A., and Z. Li, "PCEP Extension for Flow 1429 Specification", draft-ietf-pce-pcep-flowspec-12 (work in 1430 progress), October 2020. 1432 [I-D.ietf-pce-pcep-yang] 1433 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 1434 YANG Data Model for Path Computation Element 1435 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 1436 yang-15 (work in progress), October 2020. 1438 [I-D.ietf-pce-vn-association] 1439 Lee, Y., Zheng, H., and D. Ceccarelli, "Path Computation 1440 Element communication Protocol (PCEP) extensions for 1441 Establishing Relationships between sets of LSPs and 1442 Virtual Networks", draft-ietf-pce-vn-association-03 (work 1443 in progress), October 2020. 1445 [I-D.ietf-teas-actn-requirements] 1446 Lee, Y., Ceccarelli, D., Miyasaka, T., Shin, J., and K. 1447 Lee, "Requirements for Abstraction and Control of TE 1448 Networks", draft-ietf-teas-actn-requirements-09 (work in 1449 progress), March 2018. 1451 [I-D.kondreddy-pce-pcep-ls-sync-optimizations] 1452 Kondreddy, V. and M. Negi, "Optimizations of PCEP Link- 1453 State(LS) Synchronization Procedures", draft-kondreddy- 1454 pce-pcep-ls-sync-optimizations-00 (work in progress), 1455 October 2015. 1457 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 1458 (TE) Extensions to OSPF Version 2", RFC 3630, 1459 DOI 10.17487/RFC3630, September 2003, 1460 . 1462 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in 1463 Support of Generalized Multi-Protocol Label Switching 1464 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, 1465 . 1467 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 1468 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 1469 2006, . 1471 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 1472 Element (PCE)-Based Architecture", RFC 4655, 1473 DOI 10.17487/RFC4655, August 2006, 1474 . 1476 [RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in 1477 Support of Inter-Autonomous System (AS) MPLS and GMPLS 1478 Traffic Engineering", RFC 5316, DOI 10.17487/RFC5316, 1479 December 2008, . 1481 [RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF Extensions in 1482 Support of Inter-Autonomous System (AS) MPLS and GMPLS 1483 Traffic Engineering", RFC 5392, DOI 10.17487/RFC5392, 1484 January 2009, . 1486 [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP 1487 Authentication Option", RFC 5925, DOI 10.17487/RFC5925, 1488 June 2010, . 1490 [RFC6549] Lindem, A., Roy, A., and S. Mirtorabi, "OSPFv2 Multi- 1491 Instance Extensions", RFC 6549, DOI 10.17487/RFC6549, 1492 March 2012, . 1494 [RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the 1495 Path Computation Element Architecture to the Determination 1496 of a Sequence of Domains in MPLS and GMPLS", RFC 6805, 1497 DOI 10.17487/RFC6805, November 2012, 1498 . 1500 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 1501 BGP, LDP, PCEP, and MSDP Issues According to the Keying 1502 and Authentication for Routing Protocols (KARP) Design 1503 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 1504 . 1506 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 1507 "Recommendations for Secure Use of Transport Layer 1508 Security (TLS) and Datagram Transport Layer Security 1509 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 1510 2015, . 1512 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1513 Writing an IANA Considerations Section in RFCs", BCP 26, 1514 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1515 . 1517 [RFC8202] Ginsberg, L., Previdi, S., and W. Henderickx, "IS-IS 1518 Multi-Instance", RFC 8202, DOI 10.17487/RFC8202, June 1519 2017, . 1521 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 1522 Computation Element Communication Protocol (PCEP) 1523 Extensions for Stateful PCE", RFC 8231, 1524 DOI 10.17487/RFC8231, September 2017, 1525 . 1527 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 1528 "PCEPS: Usage of TLS to Provide a Secure Transport for the 1529 Path Computation Element Communication Protocol (PCEP)", 1530 RFC 8253, DOI 10.17487/RFC8253, October 2017, 1531 . 1533 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 1534 Computation Element Communication Protocol (PCEP) 1535 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 1536 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 1537 . 1539 [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An 1540 Architecture for Use of PCE and the PCE Communication 1541 Protocol (PCEP) in a Network with Central Control", 1542 RFC 8283, DOI 10.17487/RFC8283, December 2017, 1543 . 1545 [RFC8453] Ceccarelli, D., Ed. and Y. Lee, Ed., "Framework for 1546 Abstraction and Control of TE Networks (ACTN)", RFC 8453, 1547 DOI 10.17487/RFC8453, August 2018, 1548 . 1550 [RFC8637] Dhody, D., Lee, Y., and D. Ceccarelli, "Applicability of 1551 the Path Computation Element (PCE) to the Abstraction and 1552 Control of TE Networks (ACTN)", RFC 8637, 1553 DOI 10.17487/RFC8637, July 2019, 1554 . 1556 Appendix A. Examples 1558 These examples are for illustration purposes only to show how the new 1559 PCEP-LS message could be encoded. They are not meant to be an 1560 exhaustive list of all possible use cases and combinations. 1562 A.1. All Nodes 1564 Each node (PCC) in the network chooses to provide its own local node 1565 and link information, and in this way PCE can build the full link- 1566 state and TE information. 1568 +--------------------+ +--------------------+ 1569 | | | | 1570 | RTA |10.1.1.1 | RTB | 1571 | 1.1.1.1 |--------------------| 2.2.2.2 | 1572 | Area 0 | 10.1.1.2| Area 0 | 1573 | | | | 1574 +--------------------+ +--------------------+ 1575 RTA 1576 --- 1577 LS Node 1578 TLV - Local Node Descriptors 1579 Sub-TLV - 514: OSPF Area-ID: 0.0.0.0 1580 Sub-TLV - 515: Router-ID: 1.1.1.1 1581 TLV - Node Attributes TLV 1582 Sub-TLV(s) 1584 LS Link 1585 TLV - Local Node Descriptors 1586 Sub-TLV - 514: OSPF Area-ID: 0.0.0.0 1587 Sub-TLV - 515: Router-ID: 1.1.1.1 1588 TLV - Remote Node Descriptors 1589 Sub-TLV - 514: OSPF Area-ID: 0.0.0.0 1590 Sub-TLV - 515: Router-ID: 2.2.2.2 1591 TLV - Link Descriptors 1592 Sub-TLV - 259: IPv4 interface: 10.1.1.1 1593 Sub-TLV - 260: IPv4 neighbor: 10.1.1.2 1594 TLV - Link Attributes TLV 1595 Sub-TLV(s) 1597 RTB 1598 --- 1599 LS Node 1600 TLV - Local Node Descriptors 1601 Sub-TLV - 514: OSPF Area-ID: 0.0.0.0 1602 Sub-TLV - 515: Router-ID: 2.2.2.2 1604 TLV - Node Attributes TLV 1605 Sub-TLV(s) 1607 LS Link 1608 TLV - Local Node Descriptors 1609 Sub-TLV - 514: OSPF Area-ID: 0.0.0.0 1610 Sub-TLV - 515: Router-ID: 2.2.2.2 1611 TLV - Remote Node Descriptors 1612 Sub-TLV - 514: OSPF Area-ID: 0.0.0.0 1613 Sub-TLV - 515: Router-ID: 1.1.1.1 1614 TLV - Link Descriptors 1615 Sub-TLV - 259: IPv4 interface: 10.1.1.2 1616 Sub-TLV - 260: IPv4 neighbor: 10.1.1.1 1617 TLV - Link Attributes TLV 1618 Sub-TLV(s) 1620 A.2. Designated Node 1622 A designated node(s) in the network will provide its own local node 1623 as well as all learned remote information, and in this way PCE can 1624 build the full link-state and TE information. 1626 As described in Appendix A.1, the same LS Node and Link objects will 1627 be generated with a difference that it would be a designated router 1628 say RTA that generate all this information. 1630 A.3. Between PCEs 1632 As per Hierarchical-PCE [RFC6805], Parent PCE builds an abstract 1633 domain topology map with each domain as an abstract node and inter- 1634 domain links as an abstract link. Each child PCE may provide this 1635 information to the parent PCE. Considering the example in figure 1 1636 of [RFC6805], following LS object will be generated: 1638 PCE1 1639 ---- 1640 LS Node 1641 TLV - Local Node Descriptors 1642 Sub-TLV - 512: Autonomous System: 100 (Domain 1) 1643 Sub-TLV - 515: Router-ID: 11.11.11.11 (abstract) 1645 LS Link 1646 TLV - Local Node Descriptors 1647 Sub-TLV - 512: Autonomous System: 100 1648 Sub-TLV - 515: Router-ID: 11.11.11.11 (abstract) 1649 TLV - Remote Node Descriptors 1650 Sub-TLV - 512: Autonomous System: 200 (Domain 2) 1651 Sub-TLV - 515: Router-ID: 22.22.22.22 (abstract) 1652 TLV - Link Descriptors 1653 Sub-TLV - 259: IPv4 interface: 11.1.1.1 1654 Sub-TLV - 260: IPv4 neighbor: 11.1.1.2 1655 TLV - Link Attributes TLV 1656 Sub-TLV(s) 1658 LS Link 1659 TLV - Local Node Descriptors 1660 Sub-TLV - 512: Autonomous System: 100 1661 Sub-TLV - 515: Router-ID: 11.11.11.11 (abstract) 1662 TLV - Remote Node Descriptors 1663 Sub-TLV - 512: Autonomous System: 200 1664 Sub-TLV - 515: Router-ID: 22.22.22.22 (abstract) 1665 TLV - Link Descriptors 1666 Sub-TLV - 259: IPv4 interface: 12.1.1.1 1667 Sub-TLV - 260: IPv4 neighbor: 12.1.1.2 1668 TLV - Link Attributes TLV 1669 Sub-TLV(s) 1671 LS Link 1672 TLV - Local Node Descriptors 1673 Sub-TLV - 512: Autonomous System: 100 1674 Sub-TLV - 515: Router-ID: 11.11.11.11 (abstract) 1675 TLV - Remote Node Descriptors 1676 Sub-TLV - 512: Autonomous System: 400 (Domain 4) 1677 Sub-TLV - 515: Router-ID: 44.44.44.44 (abstract) 1678 TLV - Link Descriptors 1679 Sub-TLV - 259: IPv4 interface: 13.1.1.1 1680 Sub-TLV - 260: IPv4 neighbor: 13.1.1.2 1681 TLV - Link Attributes TLV 1682 Sub-TLV(s) 1684 * similar information will be generated by other PCE 1685 to help form the abstract domain topology. 1687 Further the exact border nodes and abstract internal path between the 1688 border nodes may also be transported to the Parent PCE to enable ACTN 1689 as described in [RFC8637] using the similar LS node and link objects 1690 encodings. 1692 Appendix B. Contributor Addresses 1694 Udayasree Palle 1696 EMail: udayasreereddy@gmail.com 1698 Sergio Belotti 1699 Nokia 1701 EMail: sergio.belotti@nokia.com 1703 Satish Karunanithi 1704 Huawei Technologies 1705 Divyashree Techno Park, Whitefield 1706 Bangalore, Karnataka 560066 1707 India 1709 Email: satishk@huawei.com 1711 Cheng Li 1712 Huawei Technologies 1713 Huawei Campus, No. 156 Beiqing Rd. 1714 Beijing 100095 1715 China 1717 Email: c.l@huawei.com 1719 Authors' Addresses 1721 Dhruv Dhody 1722 Huawei Technologies 1723 Divyashree Techno Park, Whitefield 1724 Bangalore, Karnataka 560066 1725 India 1727 EMail: dhruv.ietf@gmail.com 1728 Shuping Peng 1729 Huawei Technologies 1730 Huawei Bld., No.156 Beiqing Rd. 1731 Beijing 100095 1732 China 1734 EMail: pengshuping@huawei.com 1736 Young Lee 1737 Samsung Electronics 1738 Seoul 1739 South Korea 1741 EMail: younglee.tx@gmail.com 1743 Daniele Ceccarelli 1744 Ericsson 1745 Torshamnsgatan,48 1746 Stockholm 1747 Sweden 1749 EMail: daniele.ceccarelli@ericsson.com 1751 Aijun Wang 1752 China Telecom 1753 Beiqijia Town, Changping District 1754 Beijing, Beijing 102209 1755 China 1757 EMail: wangaj3@chinatelecom.cn 1759 Gyan Mishra 1760 Verizon Inc. 1762 EMail: gyan.s.mishra@verizon.com