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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 Y. Lee 4 Intended status: Informational Huawei Technologies 5 Expires: September 14, 2017 D. Ceccarelli 6 Ericsson 7 J. Shin 8 SK Telecom 9 D. King 10 Lancaster University 11 O. Gonzalez de Dios 12 Telefonica I+D 13 March 13, 2017 15 Hierarchical Stateful Path Computation Element (PCE). 16 draft-dhodylee-pce-stateful-hpce-03 18 Abstract 20 A Stateful Path Computation Element (PCE) maintains information on 21 the current network state, including: computed Label Switched Path 22 (LSPs), reserved resources within the network, and pending path 23 computation requests. This information may then be considered when 24 computing new traffic engineered LSPs, and for associated 25 and dependent LSPs, received from Path Computation Clients (PCCs). 27 The Hierarchical Path Computation Element (H-PCE) architecture, 28 provides an architecture to allow the optimum sequence of 29 inter-connected domains to be selected, and network policy to be 30 applied if applicable, via the use of a hierarchical relationship 31 between PCEs. 33 Combining the capabilities of Stateful PCE and the Hierarchical PCE 34 would be advantageous. This document describes general considerations 35 and use cases for the deployment of Stateful PCE(s) using the 36 Hierarchical PCE architecture. 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 http://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 Copyright Notice 55 Copyright (c) 2016 IETF Trust and the persons identified as the 56 document authors. All rights reserved. 58 This document is subject to BCP 78 and the IETF Trust's Legal 59 Provisions Relating to IETF Documents 60 (http://trustee.ietf.org/license-info) in effect on the date of 61 publication of this document. Please review these documents 62 carefully, as they describe your rights and restrictions with respect 63 to this document. Code Components extracted from this document must 64 include Simplified BSD License text as described in Section 4.e of 65 the Trust Legal Provisions and are provided without warranty as 66 described in the Simplified BSD License. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 71 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 72 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 73 3. Hierarchical Stateful PCE . . . . . . . . . . . . . . . . . . 4 74 3.1. Passive Operations . . . . . . . . . . . . . . . . . . . 4 75 3.2. Active Operations . . . . . . . . . . . . . . . . . . . . 7 76 3.3. PCE Initiation Operation . . . . . . . . . . . . . . . . 8 77 3.3.1. Per Domain Stitched LSP . . . . . . . . . . . . . . . 8 78 4. Other Considerations . . . . . . . . . . . . . . . . . . . . 10 79 4.1. Applicability to Inter-Layer . . . . . . . . . . . . . . 10 80 4.2. Applicability to ACTN . . . . . . . . . . . . . . . . . . 11 81 5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 82 6. Manageability Considerations . . . . . . . . . . . . . . . . 12 83 6.1. Control of Function and Policy . . . . . . . . . . . . . 12 84 6.2. Information and Data Models . . . . . . . . . . . . . . . 12 85 6.3. Liveness Detection and Monitoring . . . . . . . . . . . . 12 86 6.4. Verify Correct Operations . . . . . . . . . . . . . . . . 12 87 6.5. Requirements On Other Protocols . . . . . . . . . . . . . 12 88 6.6. Impact On Network Operations . . . . . . . . . . . . . . 12 89 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 90 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 91 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 92 9.1. Normative References . . . . . . . . . . . . . . . . . . 12 93 9.2. Informative References . . . . . . . . . . . . . . . . . 13 94 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 14 95 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 97 1. Introduction 99 The Path Computation Element communication Protocol (PCEP) provides 100 mechanisms for Path Computation Elements (PCEs) to perform path 101 computations in response to Path Computation Clients' (PCCs) 102 requests. 104 A stateful PCE is capable of considering, for the purposes of 105 path computation, not only the network state in terms of links and 106 nodes (referred to as the Traffic Engineering Database or TED) but 107 also the status of active services (previously computed paths, 108 and currently reserved resources, stored in the Label Switched 109 Paths Database (LSPDB). 111 [RFC8051] describes general considerations for a stateful PCE 112 deployment and examines its applicability and benefits, as well as 113 its challenges and limitations through a number of use cases. 115 [I-D.ietf-pce-stateful-pce] describes a set of extensions to PCEP to 116 provide stateful control. A stateful PCE has access to not only the 117 information carried by the network's Interior Gateway Protocol (IGP), 118 but also the set of active paths and their reserved resources for its 119 computations. The additional state allows the PCE to compute 120 constrained paths while considering individual LSPs and their 121 interactions. [I-D.ietf-pce-pce-initiated-lsp] describes the setup, 122 maintenance and teardown of PCE-initiated LSPs under the stateful PCE 123 model. 125 [I-D.ietf-pce-stateful-pce] also describes the active stateful PCE. 126 The active PCE functionality allows a PCE to reroute an existing 127 LSP or make changes to the attributes of an existing LSP, or delegate 128 control of specific LSPs to a new PCE. 130 The ability to compute shortest constrained TE LSPs in Multiprotocol 131 Label Switching (MPLS) and Generalized MPLS (GMPLS) networks across 132 multiple domains has been identified as a key motivation for PCE 133 development. [RFC6805] describes a Hierarchical PCE (H-PCE) 134 architecture which can be used for computing end-to-end paths for 135 inter-domain MPLS Traffic Engineering (TE) and GMPLS Label Switched 136 Paths (LSPs). Within the Hierarchical PCE (H-PCE) architecture 137 [RFC6805], the Parent PCE (P-PCE) is used to compute a multi-domain 138 path based on the domain connectivity information. A Child PCE 139 (C-PCE) may be responsible for a single domain or multiple domains, 140 it is used to compute the intra-domain path based on its domain 141 topology information. 143 This document presents general considerations for stateful PCE(s) in 144 hierarchical PCE architecture. In particular, the behavior changes 145 and additions to the existing stateful PCE mechanisms (including PCE- 146 initiated LSP setup and active PCE usage) in the context of networks 147 using the H-PCE architecture. 149 1.1. Requirements Language 151 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 152 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 153 document are to be interpreted as described in [RFC2119]. 155 2. Terminology 157 The terminology is as per [RFC4655], [RFC5440], [RFC6805], and 158 [I-D.ietf-pce-stateful-pce]. 160 3. Hierarchical Stateful PCE 162 As described in [RFC6805], in the hierarchical PCE architecture, a 163 P-PCE maintains a domain topology map that contains the child domains 164 (seen as vertices in the topology) and their interconnections (links 165 in the topology). The P-PCE has no information about the content of 166 the child domains. Each child domain has at least one PCE capable of 167 computing paths across the domain. These PCEs are known as C-PCEs 168 and have a direct relationship with the P-PCE. The P-PCE builds the 169 domain topology map either via direct configuration (allowing network 170 policy to also be applied) or from learned information received from 171 each C-PCE. 173 [I-D.ietf-pce-stateful-pce] specifies new functions to support a 174 stateful PCE. It also specifies that a function can be initiated 175 either from a PCC towards a PCE (C-E) or from a PCE towards a PCC 176 (E-C). 178 This document extends these functions to support H-PCE Architecture 179 from a C-PCE towards a P-PCE (CE-PE) or from a P-PCE 180 towards a C-PCE (PE-CE). All PCE types herein (i.e., PE or CE) 181 are assumed to be 'stateful PCE'. 183 A number of interactions are expected in the Hierarchical Stateful 184 PCE architecture, these include: 186 LSP State Report (CE-PE): a child stateful PCE sends an LSP state 187 report to a Parent Stateful PCE whenever the state of a LSP 188 changes. 190 LSP State Synchronization (CE-PE): after the session between the 191 Child and Parent stateful PCEs is initialized, the P-PCE must 192 learn the state of C-PCE's TE LSPs. 194 LSP Control Delegation (CE-PE,PE-CE): a C-PCE grants to the 195 P-PCE the right to update LSP attributes on one or more LSPs; 196 the C-PCE may withdraw the delegation or the P-PCE may 197 give up the delegation at any time. 199 LSP Update Request (PE-CE): a stateful P-PCE requests 200 modification of attributes on a C-PCE's TE LSP. 202 PCE LSP Initiation Request (PE-CE): a stateful P-PCE requests 203 C-PCE to initiate a TE LSP. 205 Note that this hierarchy is recursive and thus a LSR could delegate 206 the control to a PCE, which may delegate to its parent, which may 207 further delegate it to its parent (if it exist or needed). Similarly 208 update operations could also be applied recursively. 210 [I-D.ietf-pce-hierarchy-extensions] defines the H-PCE capability TLV 211 that should be used in the OPEN message to advertise the H-PCE 212 capability. [I-D.ietf-pce-stateful-pce] defines the stateful PCE 213 capability TLV. The presence of both TLVs represent the support for 214 stateful H-PCE operations as described in this document. 216 [I-D.litkowski-pce-state-sync] describes the procedures to allow a 217 stateful communication between PCEs for various use-cases. The 218 procedures and extensions as described in Section 3 of 219 [I-D.litkowski-pce-state-sync] are also applicable to Child and 220 Parent PCE communication. 222 3.1. Passive Operations 224 Procedures as described in [RFC6805] are applied, where the ingress 225 C-PCE sends a request to the P-PCE. The P-PCE selects a set of 226 candidate domain paths based on the domain topology and the state of 227 the inter-domain links. It then sends computation requests to the C- 228 PCEs responsible for each of the domains on the candidate domain 229 paths. Each C-PCE computes a set of candidate path segments across 230 its domain and sends the results to the P-PCE. The P-PCE uses this 231 information to select path segments and concatenate them to derive 232 the optimal end-to-end inter-domain path. The end-to-end path is 233 then sent to the C-PCE that received the initial path request, and 234 this C-PCE passes the path on to the PCC that issued the original 235 request. 237 As per [I-D.ietf-pce-stateful-pce], PCC sends an LSP State Report 238 carried on a PCRpt message to the C-PCE, indicating the LSP's status. 239 The C-PCE MAY further propagate the State Report to the P-PCE. A 240 local policy at C-PCE MAY dictate which LSPs to be reported to the P- 241 PCE. The PCRpt message is sent from C-PCE to P-PCE. 243 State synchronization mechanism as described in 244 [I-D.ietf-pce-stateful-pce] and 245 [I-D.ietf-pce-stateful-sync-optimizations] are applicable to PCEP 246 session between C-PCE and P-PCE as well. 248 Taking the sample hierarchical domain topology example from [RFC6805] 249 as the reference topology for the entirety of this document. 251 ----------------------------------------------------------------- 252 | Domain 5 | 253 | ----- | 254 | |PCE 5| | 255 | ----- | 256 | | 257 | ---------------- ---------------- ---------------- | 258 | | Domain 1 | | Domain 2 | | Domain 3 | | 259 | | | | | | | | 260 | | ----- | | ----- | | ----- | | 261 | | |PCE 1| | | |PCE 2| | | |PCE 3| | | 262 | | ----- | | ----- | | ----- | | 263 | | | | | | | | 264 | | ----| |---- ----| |---- | | 265 | | |BN11+---+BN21| |BN23+---+BN31| | | 266 | | - ----| |---- ----| |---- - | | 267 | | |S| | | | | |D| | | 268 | | - ----| |---- ----| |---- - | | 269 | | |BN12+---+BN22| |BN24+---+BN32| | | 270 | | ----| |---- ----| |---- | | 271 | | | | | | | | 272 | | ---- | | | | ---- | | 273 | | |BN13| | | | | |BN33| | | 274 | -----------+---- ---------------- ----+----------- | 275 | \ / | 276 | \ ---------------- / | 277 | \ | | / | 278 | \ |---- ----| / | 279 | ----+BN41| |BN42+---- | 280 | |---- ----| | 281 | | | | 282 | | ----- | | 283 | | |PCE 4| | | 284 | | ----- | | 285 | | | | 286 | | Domain 4 | | 287 | ---------------- | 288 | | 289 ----------------------------------------------------------------- 291 Figure 1: Sample Hierarchical Domain Topology 293 Steps 1 to 11 are exactly as described in section 4.6.2 (Hierarchical 294 PCE End-to-End Path Computation Procedure) of [RFC6805], the 295 following additional steps are added for stateful PCE: 297 (1) The Ingress LSR initiates the setup of the LSP as per the path 298 and reports to the PCE1 the LSP status ("GOING-UP"). 300 (2) The PCE1 further reports the status of the LSP to the P-PCE 301 (PCE5). 303 (3) The Ingress LSR notifies the LSP state to PCE1 when the state is 304 "UP". 306 (4) The PCE1 further reports the status of the LSP to the P-PCE 307 (PCE5). 309 3.2. Active Operations 311 [I-D.ietf-pce-stateful-pce] describes the case of active stateful 312 PCE. The active PCE functionality uses two specific PCEP messages: 314 o Update Request (PCUpd) 315 o State Report (PCRpt) 317 The first is sent by the PCE to a Path Computation Client (PCC) for 318 modifying LSP attributes. The PCC sends back a PCRpt to acknowledge 319 the requested operation or report any change in LSP's state. 321 As per [RFC8051], Delegation is an operation to 322 grant a PCE, temporary rights to modify a subset of LSP parameters on 323 one or more PCC's LSPs. The C-PCE may further choose to delegate 324 to P-PCE based on a local policy. The PCRpt message with "D" 325 (delegate) flag is sent from C-PCE to P-PCE. 327 To update an LSP, a PCE send to the PCC, an LSP Update Request using 328 a PCUpd message. For LSP delegated to the P-PCE via the child 329 PCE, the P-PCE can use the same PCUpd message to request change 330 to the C-PCE (the Ingress domain PCE), the PCE further propagates 331 the update request to the PCC. 333 The P-PCE uses the same mechanism described in Section 3.1 to compute 334 the end to end path using PCReq and PCRep messages. 336 The following additional steps are also initially performed, 337 for active operations, again using the reference architecture 338 described in Figure 1 (Sample Hierarchical Domain Topology). 340 (1) The Ingress LSR delegates the LSP to the PCE1 via PCRpt message 341 with D flag set. 343 (2) The PCE1 further delegates the LSP to the P-PCE (PCE5). 345 Steps 4 to 10 of section 4.6.2 of [RFC6805] are executed to determine 346 the end to end path. 348 (3) The P-PCE (PCE5) sends the update request to the C-PCE 349 (PCE1) via PCUpd message. 351 (4) The PCE1 further updates the LSP to the Ingress LSR (PCC). 353 (5) The Ingress LSR initiates the setup of the LSP as per the path 354 and reports to the PCE1 the LSP status ("GOING-UP"). 356 (6) The PCE1 further reports the status of the LSP to the P-PCE 357 (PCE5). 359 (7) The Ingress LSR notifies the LSP state to PCE1 when the state is 360 "UP". 362 (8) The PCE1 further reports the status of the LSP to the P-PCE 363 (PCE5). 365 3.3. PCE Initiation Operation 367 [I-D.ietf-pce-pce-initiated-lsp] describes the setup, maintenance and 368 teardown of PCE-initiated LSPs under the stateful PCE model, without 369 the need for local configuration on the PCC, thus allowing for a 370 dynamic network that is centrally controlled and deployed. To 371 instantiate or delete an LSP, the PCE sends the Path Computation LSP 372 Initiate Request (PCInitiate) message to the PCC. In case of inter- 373 domain LSP in Hierarchical PCE architecture, the initiation 374 operations can be carried out at the P-PCE. In which case after 375 P-PCE finishes the E2E path computation, it can send the 376 PCInitiate message to the C-PCE (the Ingress domain PCE), the PCE 377 further propagates the initiate request to the PCC. 379 The following additional steps are also initially performed, 380 for PCE initiated operations, again using the reference 381 architecture described in Figure 1 (Sample Hierarchical Domain 382 Topology): 384 (1) The P-PCE (PCE5) is requested to initiate a LSP. 386 Steps 4 to 10 of section 4.6.2 of [RFC6805] are executed to determine 387 the end to end path. 389 (2) The P-PCE (PCE5) sends the initiate request to the child 390 PCE (PCE1) via PCInitiate message. 392 (3) The PCE1 further propagates the initiate message to the Ingress 393 LSR (PCC). 395 (4) The Ingress LSR initiates the setup of the LSP as per the path 396 and reports to the PCE1 the LSP status ("GOING-UP"). 398 (5) The PCE1 further reports the status of the LSP to the P-PCE 399 (PCE5). 401 (6) The Ingress LSR notifies the LSP state to PCE1 when the state is 402 "UP". 404 (7) The PCE1 further reports the status of the LSP to the P-PCE 405 (PCE5). 407 3.3.1. Per Domain Stitched LSP 409 The hierarchical PCE architecture as per [RFC6805] is primarily used 410 for E2E LSP. With PCE-Initiated capability, another mode of 411 operation is possible, where multiple intra-domain LSPs are initiated 412 in each domain which are further stitched to form an E2E LSP. The 413 P-PCE sends PCInitiate message to each C-PCE separately to 414 initiate individual LSP segments along the domain path. These 415 individual per domain LSP are stitched together by some mechanism, 416 which is out of scope of this document. The P-PCE may also send 417 the PCInitiate message to the ingress C-PCE to initiate the E2E 418 LSP separately. 420 The following additional steps are also initially performed, 421 for the Per Domain stiched LSP operation, again using the reference 422 architecture described in Figure 1 (Sample Hierarchical Domain 423 Topology): 425 (1) The P-PCE (PCE5) is requested to initiate a LSP. 427 Steps 4 to 10 of section 4.6.2 of [RFC6805] are executed to determine 428 the end to end path, which are broken into per-domain LSPs say - 430 o S-BN41 432 o BN41-BN33 434 o BN33-D 436 It should be noted that the P-PCE MAY use other mechanisms to 437 determine the suitable per-domain LSPs (apart from [RFC6805]). 439 For LSP (BN33-D) 441 (2) The P-PCE (PCE5) sends the initiate request to the child 442 PCE (PCE3) via PCInitiate message for LSP (BN33-D). 444 (3) The PCE3 further propagates the initiate message to BN33. 446 (4) BN33 initiates the setup of the LSP as per the path and reports 447 to the PCE3 the LSP status ("GOING-UP"). 449 (5) The PCE3 further reports the status of the LSP to the P-PCE 450 (PCE5). 452 (6) The node BN33 notifies the LSP state to PCE3 when the state is 453 "UP". 455 (7) The PCE3 further reports the status of the LSP to the P-PCE 456 (PCE5). 458 For LSP (BN41-BN33) 460 (8) The P-PCE (PCE5) sends the initiate request to the child PCE 461 (PCE4) via PCInitiate message for LSP (BN41-BN33). 463 (9) The PCE4 further propagates the initiate message to BN41. 465 (10) BN41 initiates the setup of the LSP as per the path and reports 466 to the PCE4 the LSP status ("GOING-UP"). 468 (11) The PCE4 further reports the status of the LSP to the P-PCE 469 (PCE5). 471 (l2) The node BN41 notifies the LSP state to PCE4 when the state is 472 "UP". 474 (13) The PCE4 further reports the status of the LSP to the P-PCE 475 (PCE5). 477 For LSP (S-BN41) 479 (14) The P-PCE (PCE5) sends the initiate request to the child 480 PCE (PCE1) via PCInitiate message for LSP (S-BN41). 482 (15) The PCE1 further propagates the initiate message to node S. 484 (16) S initiates the setup of the LSP as per the path and reports to 485 the PCE1 the LSP status ("GOING-UP"). 487 (17) The PCE1 further reports the status of the LSP to the P-PCE 488 (PCE5). 490 (18) The node S notifies the LSP state to PCE1 when the state is 491 "UP". 493 (19) The PCE1 further reports the status of the LSP to the P-PCE 494 (PCE5). 496 Additionally: 498 (20) Once P-PCE receives report of each per-domain LSP, it 499 should use some stitching mechanism, which is out of scope of 500 this document. In this step, P-PCE (PCE5) could also initiate 501 an E2E LSP (S-D) by sending the PCInitiate message to Ingress 502 C-PCE (PCE1). 504 4. Other Considerations 506 4.1. Applicability to Inter-Layer 508 [RFC5623] describes a framework for applying the PCE-based 509 architecture to inter-layer (G)MPLS traffic engineering. The H-PCE 510 Stateful architecture with stateful P-PCE coordinating with the 511 stateful C-PCEs of higher and lower layer is shown in the figure 512 below. 514 +----------+ 515 /| Parent | 516 / | PCE | 517 / +----------+ 518 / / Stateful 519 / / 520 / / 521 / / 522 Stateful +---+/ / 523 Child + PCE + / 524 PCE Hi + Hi + / 525 +---+ / 526 +---+ +---+ / +---+ +---+ 527 + LSR +--+ LSR +........................+ LSR +--+ LSR + 528 + H1 + + H2 + / + H3 + + H4 + 529 +---+ +---+\ +---+/ /+---+ +---+ 530 \ + PCE + / 531 \ + Lo + / 532 Stateful \ +---+ / 533 C-PCE \ / 534 Lo \+---+ +---+/ 535 + LSR +--+ LSR + 536 + L1 + + L2 + 537 +---+ +---+ 539 Figure 2: Sample Inter-Layer Topology 541 All procedures described in Section 3 are applicable to inter-layer 542 path setup as well. 544 4.2. Applicability to ACTN 546 [I-D.ietf-teas-actn-framework] describes framework for 547 Abstraction and Control of TE Networks (ACTN), where each Physical 548 Network Controller (PNC) is equivalent to C-PCE and P-PCE is 549 the Multi-Domain Service Coordinator (MDSC). The Per domain stitched 550 LSP as per the Hierarchical PCE architecture described in 551 Section 3.3.1 and Section 4.1 is well suited for ACTN. 553 [I-D.dhody-pce-applicability-actn] examines the applicability of PCE 554 to the ACTN framework. To support the function of multi domain 555 coordination via hierarchy, the stateful hierarchy of PCEs plays a 556 crucial role. 558 In ACTN framework, Customer Network Controller (CNC) can request the 559 MDSC to check if there is a possibility to meet Virtual Network (VN) 560 requirements (before requesting for VN provision). The H-PCE 561 architecture as described in [RFC6805] can supports via the use of 562 PCReq and PCRep messages between the P-PCE and C-PCEs. 564 5. Scalability Considerations 566 It should be noted that if all the C-PCEs would report all the LSPs 567 in their domain, it could lead to scalability issues for the P-PCE. 568 Thus it is recommended to only report the LSPs which are involved in 569 H-PCE, i.e. the LSPs which are either delegated to the P-PCE or 570 initiated by the P-PCE. Scalability considerations for PCEP as per 571 [I-D.ietf-pce-stateful-pce] continue to apply for the PCEP session 572 between child and parent PCE. 574 6. Security Considerations 576 The security considerations listed in [I-D.ietf-pce-stateful- 577 pce],[RFC6805] and [RFC5440] apply to this document as well. As per 578 [RFC6805], it is expected that the parent PCE will require all child 579 PCEs to use full security when communicating with the parent. 581 Any multi-domain operation necessarily involves the exchange of 582 information across domain boundaries. This is bound to represent a 583 significant security and confidentiality risk especially when the 584 child domains are controlled by different commercial concerns. PCEP 585 allows individual PCEs to maintain confidentiality of their domain 586 path information using path-keys [RFC5520], and the hierarchical PCE 587 architecture is specifically designed to enable as much isolation of 588 domain topology and capabilities information as is possible. The LSP 589 state in the PCRpt message SHOULD continue to use this. 591 The security consideration for PCE-Initiated LSP as per 592 [I-D.ietf-pce-pce-initiated-lsp] is also applicable from P-PCE to C- 593 PCE. 595 Thus securing the PCEP session (between the P-PCE and the C-PCE) 596 using mechanism like TCP Authentication Option (TCP-AO) [RFC5925] or 597 Transport Layer Security (TLS) [I-D.ietf-pce-pceps] is RECOMMENDED. 599 7. Manageability Considerations 601 All manageability requirements and considerations listed in 602 [RFC5440], [RFC6805], [I-D.ietf-pce-stateful-pce], and 603 [I-D.ietf-pce-pce-initiated-lsp] apply to Stateful H-PCE defined in 604 this document. In addition, requirements and considerations listed 605 in this section apply. 607 7.1. Control of Function and Policy 609 Support of the hierarchical procedure will be controlled by the 610 management organization responsible for each child PCE. The parent 611 PCE must only accept path computation requests from authorized child 612 PCEs. If a parent PCE receives report from an unauthorized child 613 PCE, the report should be dropped. All mechanism as described in [I- 614 D.ietf-pce-stateful-pce] and [I-D.ietf-pce-pce-initiated-lsp] 615 continue to apply. 617 7.2. Information and Data Models 619 An implementation SHOULD allow the operator to view the stateful and 620 H-PCE capabilities advertised by each peer. The PCEP YANG module [I- 621 D.ietf-pce-pcep-yang] can be extended to include details stateful H- 622 PCE. 624 7.3. Liveness Detection and Monitoring 626 Mechanisms defined in this document do not imply any new liveness 627 detection and monitoring requirements in addition to those already 628 listed in [RFC5440]. 630 7.4. Verify Correct Operations 632 Mechanisms defined in this document do not imply any new operation 633 verification requirements in addition to those already listed in 634 [RFC5440] and [I-D.ietf-pce-stateful-pce]. 636 7.5. Requirements On Other Protocols 638 Mechanisms defined in this document do not imply any new requirements 639 on other protocols. 641 7.6. Impact On Network Operations 643 Mechanisms defined in [RFC5440] and [I-D.ietf-pce-stateful-pce] also 644 apply to PCEP extensions defined in this document. 646 The stateful H-PCE technique brings the applicability of stateful PCE 647 as described in [RFC8051], for the LSP traversing multiple domains. 649 8. IANA Considerations 651 There are no IANA considerations. 653 9. Acknowledgments 655 Thanks to Manuela Scarella, Haomian Zheng, Sergio Marmo, Stefano 656 Parodi, Giacomo Agostini, Jeff Tantsura and Rajan Rao for 657 suggestions. 659 10. References 661 10.1. Normative References 663 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 664 Requirement Levels", BCP 14, RFC 2119, 665 DOI 10.17487/RFC2119, March 1997, 666 . 668 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 669 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 670 DOI 10.17487/RFC5440, March 2009, 671 . 673 [RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the 674 Path Computation Element Architecture to the Determination 675 of a Sequence of Domains in MPLS and GMPLS", RFC 6805, DOI 676 10.17487/RFC6805, November 2012, 677 . 679 [I-D.ietf-pce-stateful-pce] 680 Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP 681 Extensions for Stateful PCE", draft-ietf-pce-stateful- 682 pce-18 (work in progress), December 2016. 684 [I-D.ietf-pce-pce-initiated-lsp] 685 Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP 686 Extensions for PCE-initiated LSP Setup in a Stateful PCE 687 Model", draft-ietf-pce-pce-initiated-lsp-09 (work in 688 progress), March 2017. 690 10.2. Informative References 692 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 693 Element (PCE)-Based Architecture", RFC 4655, 694 DOI 10.17487/RFC4655, August 2006, 695 . 697 [RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel, 698 "Preserving Topology Confidentiality in Inter-Domain Path 699 Computation Using a Path-Key-Based Mechanism", RFC 5520, 700 DOI 10.17487/RFC5520, April 2009, 701 . 703 [RFC5623] Oki, E., Takeda, T., Le Roux, JL., and A. Farrel, 704 "Framework for PCE-Based Inter-Layer MPLS and GMPLS 705 Traffic Engineering", RFC 5623, DOI 10.17487/RFC5623, 706 September 2009, . 708 [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP 709 Authentication Option", RFC 5925, DOI 10.17487/RFC5925, 710 June 2010, . 712 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 713 Stateful Path Computation Element (PCE)", RFC 8051, 714 DOI 10.17487/RFC8051, January 2017, 715 . 717 [I-D.ietf-pce-stateful-sync-optimizations] 718 Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 719 and D. Dhody, "Optimizations of Label Switched Path State 720 Synchronization Procedures for a Stateful PCE", draft- 721 ietf-pce-stateful-sync-optimizations-09 (work in 722 progress), February 2017. 724 [I-D.ietf-teas-actn-framework] 725 Ceccarelli D. and Y. Lee, "Framework for Abstraction and 726 Control of Transport Networks", draft-ietf-teas- 727 actn-framework-04 (work in progress), February 2017. 729 [I-D.dhody-pce-applicability-actn] 730 Dhody, D., Lee, Y., and D. Ceccarelli, "Applicability of 731 Path Computation Element (PCE) for Abstraction and 732 Control of TE Networks (ACTN)", draft-dhody-pce- 733 applicability-actn-01 (work in progress), October 2016. 735 [I-D.litkowski-pce-state-sync] 736 Litkowski, S., Sivabalan, S., and D. Dhody, "Inter 737 Stateful Path Computation Element communication 738 procedures", draft-litkowski-pce-state-sync-01 (work in 739 progress), February 2017. 741 [I-D.ietf-pce-hierarchy-extensions] 742 Zhang, F., Zhao, Q., Dios, O., Casellas, R., and D. King, 743 "Extensions to Path Computation Element Communication 744 Protocol (PCEP) for Hierarchical Path Computation Elements 745 (PCE)", draft-ietf-pce-hierarchy-extensions-03 (work in 746 progress), July 2016. 748 [I-D.ietf-pce-pceps] 749 Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure 750 Transport for PCEP", draft-ietf-pce-pceps-11 (work in 751 progress), January 2017. 753 Appendix A. Contributor Addresses 755 Avantika 756 Huawei Technologies 757 Divyashree Techno Park, Whitefield 758 Bangalore, Karnataka 560066 759 India 761 EMail: avantika.sushilkumar@huawei.com 763 Xian Zhang 764 Huawei Technologies 765 Bantian, Longgang District 766 Shenzhen, Guangdong 518129 767 P.R.China 769 EMail: zhang.xian@huawei.com 771 Udayasree Palle 772 Huawei Technologies 773 Divyashree Techno Park, Whitefield 774 Bangalore, Karnataka 560066 775 India 777 EMail: udayasree.palle@huawei.com 779 Authors' Addresses 781 Dhruv Dhody 782 Huawei Technologies 783 Divyashree Techno Park, Whitefield 784 Bangalore, Karnataka 560066 785 India 787 EMail: dhruv.ietf@gmail.com 789 Young Lee 790 Huawei Technologies 791 5340 Legacy Drive, Building 3 792 Plano, TX 75023 793 USA 795 EMail: leeyoung@huawei.com 797 Daniele Ceccarelli 798 Ericsson 799 Torshamnsgatan,48 800 Stockholm 801 Sweden 803 EMail: daniele.ceccarelli@ericsson.com 805 Jongyoon Shin 806 SK Telecom 807 6 Hwangsaeul-ro, 258 beon-gil, Bundang-gu, Seongnam-si, 808 Gyeonggi-do 463-784 809 Republic of Korea 811 EMail: jongyoon.shin@sk.com 813 Dan King 814 Lancaster University 815 UK 817 EMail: d.king@lancaster.ac.uk 819 Oscar Gonzalez de Dios 820 Telefonica I+D 821 Don Ramon de la Cruz 82-84 822 Madrid, 28045 823 Spain 825 Phone: +34913128832 826 Email: ogondio@tid.es