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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'Ta' is mentioned on line 358, but not defined == Missing Reference: 'Tb' is mentioned on line 358, but not defined == Missing Reference: 'TBD1' is mentioned on line 581, but not defined == Missing Reference: 'TBD2' is mentioned on line 691, but not defined == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-13 == Outdated reference: A later version (-10) exists of draft-litkowski-pce-state-sync-07 Summary: 0 errors (**), 0 flaws (~~), 7 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group H. Chen, Ed. 3 Internet-Draft Futurewei 4 Intended status: Standards Track Y. Zhuang, Ed. 5 Expires: January 13, 2021 Q. Wu 6 Huawei 7 D. Ceccarelli 8 Ericsson 9 July 12, 2020 11 PCEP Extensions for LSP scheduling with stateful PCE 12 draft-ietf-pce-stateful-pce-lsp-scheduling-20 14 Abstract 16 This document defines a set of extensions needed to the stateful Path 17 Computation Element (PCE) communication Protocol (PCEP), so as to 18 enable Labeled Switched Path (LSP) scheduling for path computation 19 and LSP setup/deletion based on the actual network resource usage and 20 the duration of a traffic service in a centralized network 21 environment as stated in RFC 8413. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on January 13, 2021. 40 Copyright Notice 42 Copyright (c) 2020 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 58 2. Conventions used in this document . . . . . . . . . . . . . . 4 59 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 60 3. Motivation and Objectives . . . . . . . . . . . . . . . . . . 5 61 4. Procedures and Mechanisms . . . . . . . . . . . . . . . . . . 5 62 4.1. LSP Scheduling Overview . . . . . . . . . . . . . . . . . 5 63 4.2. Support of LSP Scheduling . . . . . . . . . . . . . . . . 7 64 4.2.1. LSP Scheduling . . . . . . . . . . . . . . . . . . . 7 65 4.2.2. Periodical LSP Scheduling . . . . . . . . . . . . . . 7 66 4.3. Scheduled LSP creation . . . . . . . . . . . . . . . . . 9 67 4.4. Scheduled LSP Modifications . . . . . . . . . . . . . . . 10 68 4.5. Scheduled LSP activation and deletion . . . . . . . . . . 11 69 5. PCEP Objects and TLVs . . . . . . . . . . . . . . . . . . . . 11 70 5.1. Stateful PCE Capability TLV . . . . . . . . . . . . . . . 11 71 5.2. LSP Object . . . . . . . . . . . . . . . . . . . . . . . 12 72 5.2.1. SCHED-LSP-ATTRIBUTE TLV . . . . . . . . . . . . . . . 12 73 5.2.2. SCHED-PD-LSP-ATTRIBUTE TLV . . . . . . . . . . . . . 15 74 6. The PCEP Messages . . . . . . . . . . . . . . . . . . . . . . 16 75 6.1. The PCRpt Message . . . . . . . . . . . . . . . . . . . . 16 76 6.2. The PCUpd Message . . . . . . . . . . . . . . . . . . . . 16 77 6.3. The PCInitiate Message . . . . . . . . . . . . . . . . . 17 78 6.4. The PCReq message . . . . . . . . . . . . . . . . . . . . 17 79 6.5. The PCRep Message . . . . . . . . . . . . . . . . . . . . 17 80 6.6. The PCErr Message . . . . . . . . . . . . . . . . . . . . 17 81 7. Implementation Status . . . . . . . . . . . . . . . . . . . . 18 82 8. Security Considerations . . . . . . . . . . . . . . . . . . . 19 83 9. Manageability Consideration . . . . . . . . . . . . . . . . . 19 84 9.1. Control of Function and Policy . . . . . . . . . . . . . 19 85 9.2. Information and Data Models . . . . . . . . . . . . . . . 19 86 9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 19 87 9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 20 88 9.5. Requirements On Other Protocols . . . . . . . . . . . . . 20 89 9.6. Impact On Network Operations . . . . . . . . . . . . . . 20 90 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 91 10.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 20 92 10.1.1. Opt Field in SCHED-PD-LSP-ATTRIBUTE TLV . . . . . . 20 93 10.1.2. Schedule TLVs Flag Field . . . . . . . . . . . . . . 21 94 10.2. STATEFUL-PCE-CAPABILITY TLV Flag field . . . . . . . . . 21 95 10.3. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 21 96 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22 97 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 98 12.1. Normative References . . . . . . . . . . . . . . . . . . 22 99 12.2. Informative References . . . . . . . . . . . . . . . . . 23 100 Appendix A. Contributors Addresses . . . . . . . . . . . . . . . 24 101 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 103 1. Introduction 105 The Path Computation Element Protocol (PCEP) defined in [RFC5440] is 106 used between a Path Computation Element (PCE) and a Path Computation 107 Client (PCC) (or other PCE) to enable path computation of Multi- 108 protocol Label Switching (MPLS) Traffic Engineering Label Switched 109 Paths (TE LSPs). 111 [RFC8231] describes a set of extensions to PCEP to provide stateful 112 control. A stateful PCE has access to not only the information 113 carried by the network's Interior Gateway Protocol (IGP) but also the 114 set of active paths and their reserved resources for its 115 computations. The additional state allows the PCE to compute 116 constrained paths while considering individual LSPs and their 117 interactions. 119 Traditionally, the usage and allocation of network resources, 120 especially bandwidth, can be supported by a Network Management System 121 (NMS) operation such as path pre-establishment. However, this does 122 not provide efficient usage of network resources. The established 123 paths reserve the resources forever, which can not be used by other 124 services even when they are not used for transporting any service. 125 [RFC8413] then provides a framework that describes and discusses the 126 problem, and defines an appropriate architecture for the scheduled 127 reservation of TE resources. 129 The scheduled reservation of TE resources allows network operators to 130 reserve resources in advance according to the agreements with their 131 customers, and allows them to transmit data about scheduling such as 132 a specified start time and duration, for example for a scheduled bulk 133 data replication between data centers. It enables the activation of 134 bandwidth usage at the time the service is really being used while 135 letting other services use it when this service is not using it. The 136 requirement of scheduled LSP provision is mentioned in [RFC8231] and 137 [RFC7399]. A solution for providing more efficient network resource 138 usage for traffic engineering is desired. Also, for deterministic 139 networks [I-D.ietf-detnet-architecture], the scheduled LSP or 140 temporal LSP can provide a better network resource usage for 141 guaranteed links. This idea can also be applied in segment routing 142 [RFC8402] to schedule the network resources over the whole network in 143 a centralized manner as well. 145 With this in mind, this document defines a set of extensions needed 146 to PCEP used for stateful PCEs so as to enable LSP scheduling for 147 path computation and LSP setup/deletion based on the actual network 148 resource usage duration of a traffic service. A scheduled LSP is 149 characterized by a starting time and a duration. When the end of the 150 LSP life is reached, it is deleted to free up the resources for other 151 LSPs (scheduled or not). 153 2. Conventions used in this document 155 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 156 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 157 "OPTIONAL" in this document are to be interpreted as described in BCP 158 14 [RFC2119] [RFC8174] when, and only when, they appear in all 159 capitals, as shown here. 161 2.1. Terminology 163 The following terminologies are re-used from existing PCE documents. 165 o Active Stateful PCE [RFC8231]; 167 o Passive Stateful PCE [RFC8231]; 169 o Delegation [RFC8231]; 171 o PCE-Initiated LSP [RFC8281]; 173 o PCC [RFC5440], [RFC8231]; 175 o PCE [RFC5440], [RFC8231]; 177 o TE LSP [RFC5440], [RFC8231]; 179 o TED [RFC5440], [RFC8231]; 181 o LSP-DB [RFC8231]; 183 In addition, this document defines the following terminologies. 185 Scheduled TE LSP (or Scheduled LSP for short): an LSP with the 186 scheduling attributes, that carries traffic flow demand at a 187 starting time and lasts for a certain duration (or from a starting 188 time to an ending time, where the ending time is the starting time 189 plus the duration). A scheduled LSP is also called a temporal 190 LSP. The PCE operates path computation per LSP availability for 191 the required time and duration. 193 Scheduled LSP-DB: a database of scheduled LSPs. 195 Scheduled TED: Traffic engineering database with the awareness of 196 scheduled resources for TE. This database is generated by the PCE 197 from the information in TED and scheduled LSP-DB and allows 198 knowing, at any time, the amount of available resources (does not 199 include failures in the future). 201 Starting time (start-time): This value indicates when the scheduled 202 LSP is used and the corresponding LSP must be setup and active. 203 In other time (i.e., before the starting time or after the 204 starting time plus Duration), the LSP can be inactive to include 205 the possibility of the resources being used by other services. 207 Duration: This value indicates the time duration that the LSP is 208 undertaken by a traffic flow and the corresponding LSP must be 209 setup and active. At the end of which, the LSP is torn down and 210 removed from the database. 212 3. Motivation and Objectives 214 A stateful PCE [RFC8231] can support better efficiency by using LSP 215 scheduling described in the use case of [RFC8051]. This requires the 216 PCE to maintain the scheduled LSPs and their associated resource 217 usage, e.g. bandwidth for Packet-switched network, as well as have 218 the ability to trigger signaling for the LSP setup/tear-down at the 219 correct time. 221 Note that existing configuration tools can be used for LSP 222 scheduling, but as highlighted in section 3.1.3 of [RFC8231] as well 223 as discussions in [RFC8413], doing this as a part of PCEP in a 224 centralized manner, has obvious advantages. 226 This document provides a set of extensions to PCEP to enable LSP 227 scheduling for LSP creation/deletion under the stateful control of a 228 PCE and according to traffic service requests from customers, so as 229 to improve the usage of network resources. 231 4. Procedures and Mechanisms 233 4.1. LSP Scheduling Overview 235 The LSP scheduling allows PCEs and PCCs to provide scheduled LSP for 236 customers' traffic services at its actual usage time, so as to 237 improve the network resource efficient utilization. 239 For stateful PCE supporting LSP scheduling, there are two types of 240 LSP databases used in this document. One is the LSP-DB defined in 241 PCEP [RFC8231], while the other is the scheduled LSP database (SLSP- 242 DB, see section 6). The SLSP-DB records scheduled LSPs and is used 243 in conjunction with the TED and LSP-DB. Note that the two types of 244 LSP databases can be implemented in one physical database or two 245 different databases. This is an implementation matter and this 246 document does not state any preference. 248 Furthermore, a scheduled TED can be generated from the scheduled LSP- 249 DB, LSP-DB and TED to indicate the network links and nodes with 250 resource availability information for now and future. The scheduled 251 TED should be maintained by all PCEs within the network environment. 253 In case of implementing PCC-initiated scheduled LSPs, before a PCC 254 delegates a scheduled LSP, it MAY use the PCReq/PCRep messages to 255 learn the path for the scheduled LSP. A PCC MUST delegate a 256 scheduled LSP with information of its scheduling parameters, 257 including the starting time and the duration using PCRpt message. 258 Since the LSP is not yet signaled, at the time of delegation the LSP 259 would be in down state. Upon receiving the delegation of the 260 scheduled LSP, a stateful PCE SHALL check the scheduled TED for the 261 network resource availability on network nodes and compute a path for 262 the LSP with the scheduling information and update to the PCC as per 263 the active stateful PCE techniques [RFC8231]. 265 Note that the active stateful PCE can update to the PCC with the path 266 for the scheduled LSP at any time. However, the PCC should not 267 signal the LSP over the path on receiving these messages since the 268 path is not active yet; PCC signals the LSP at the starting time. 270 For a multiple PCE environment, a PCE MUST synchronize to other PCEs 271 within the network, so as to keep their scheduling information 272 synchronized. There are many ways that this could be achieved: one 273 such mechanism is described in [I-D.litkowski-pce-state-sync]. Which 274 way is used to achieve this is out of scope for this document. The 275 scheduled TED can be determined from the synchronized SLSP-DB. The 276 PCE with delegation for the scheduled LSP would report the scheduled 277 LSP to other PCEs, any future update to the scheduled LSP is also 278 updated to other PCEs. This way the state of all scheduled LSPs are 279 synchronized among the PCEs. [RFC7399] discusses some 280 synchronization issues and considerations, that are also applicable 281 to the scheduled databases. 283 The scheduled LSP can also be initiated by PCE itself. In case of 284 implementing PCE-initiated scheduled LSP, the stateful PCE shall 285 check the network resource availability for the traffic and computes 286 a path for the scheduled LSP and initiate a scheduled LSP at the PCC 287 and synchronize the scheduled LSP to other PCEs. Note that, the PCC 288 could be notified immediately or at the starting time of the 289 scheduled LSP based on the local policy. For the former SCHED-LSP- 290 ATTRIBUTE TLV (see Section 5.2.1) MUST be included in the message 291 where as for the latter SCHED-LSP-ATTRIBUTE TLV SHOULD NOT be 292 included. Either way the synchronization to other PCEs should be 293 done when the scheduled LSP is created. 295 In both modes, for activation of scheduled LSPs, the PCC could 296 initiate the setup of scheduled LSP at the start time by itself or 297 wait for the PCE to update the PCC to initiate the setup of LSP. 298 Similarly on scheduled usage expires, the PCC could initiate the 299 removal by itself or wait for the PCE to request the removal of the 300 LSP. This is based on the Flag set in SCHED-LSP-ATTRIBUTE TLV. 302 4.2. Support of LSP Scheduling 304 4.2.1. LSP Scheduling 306 For a scheduled LSP, a user configures it with an arbitrary 307 scheduling duration from time Ta to time Tb, which may be represented 308 as [Ta, Tb]. 310 When an LSP is configured with arbitrary scheduling duration [Ta, 311 Tb], a path satisfying the constraints for the LSP in the scheduling 312 duration is computed and the LSP along the path is set up to carry 313 traffic from time Ta to time Tb. 315 4.2.2. Periodical LSP Scheduling 317 In addition to LSP Scheduling at an arbitrary time period, there are 318 also periodical LSP Scheduling. 320 A periodical LSP Scheduling means an LSP has multiple time intervals 321 and the LSP is set up to carry traffic in every time interval. It 322 has a scheduling duration such as [Ta, Tb], a number of repeats such 323 as 10 (repeats 10 times), and a repeat cycle/time interval such as a 324 week (repeats every week). The scheduling interval: "[Ta, Tb] 325 repeats n times with repeat cycle C" represents n+1 scheduling 326 intervals as follows: 328 [Ta, Tb], [Ta+C, Tb+C], [Ta+2C, Tb+2C], ..., [Ta+nC, Tb+nC] 330 When an LSP is configured with a scheduling interval such as "[Ta, 331 Tb] repeats 10 times with a repeat cycle a week" (representing 11 332 scheduling intervals), a path satisfying the constraints for the LSP 333 in every interval represented by the periodical scheduling interval 334 is computed once. And then the LSP along the path is set up to carry 335 traffic in each of the scheduling intervals. If there is no path 336 satisfying the constraints for some of the intervals, the LSP will 337 not be set up at all. It SHOULD generate a PCEP Error (PCErr) with 338 Error-type = 29 (Path computation failure) and Error-value = TBD7 339 (Constraints could not be met for some intervals). 341 4.2.2.1. Elastic Time LSP Scheduling 343 In addition to the basic LSP scheduling at an arbitrary time period, 344 another option is elastic time intervals, which is represented as 345 within -P and Q, where P and Q is an amount of time such as 300 346 seconds. P is called elastic range lower bound and Q is called 347 elastic range upper bound. 349 For a simple time interval such as [Ta, Tb] with an elastic range, 350 elastic time interval: "[Ta, Tb] within -P and Q" means a time period 351 from (Ta+X) to (Tb+X), where -P <= X <= Q. Note that both Ta and Tb 352 are shifted by the same 'X'. 354 When an LSP is configured with elastic time interval "[Ta, Tb] within 355 -P and Q", a path is computed such that the path satisfies the 356 constraints for the LSP in the time period from (Ta+Xv) to (Tb+Xv) 357 and |Xv| is the minimum value for Xv from -P to Q. That is, [Ta+Xv, 358 Tb+Xv] is the time interval closest to time interval [Ta, Tb] within 359 the elastic range. The LSP along the path is set up to carry traffic 360 in the time period from (Ta+Xv) to (Tb+Xv). 362 Similarly, for a recurrent time interval with an elastic range, 363 elastic time interval: "[Ta, Tb] repeats n times with repeat cycle C 364 within -P and Q" represents n+1 simple elastic time intervals as 365 follows: 367 [Ta+X0, Tb+X0], [Ta+C+X1, Tb+C+X1], ..., [Ta+nC+Xn, Tb+nC+Xn] 368 where -P <= Xi <= Q, i = 0, 1, 2, ..., n. 370 If a user wants to keep the same repeat cycle between any two 371 adjacent time intervals, elastic time interval: "[Ta, Tb] repeats n 372 times with repeat cycle C within -P and Q SYNC" may be used, which 373 represents n+1 simple elastic time intervals as follows: 375 [Ta+X, Tb+X], [Ta+C+X, Tb+C+X], ..., [Ta+nC+X, Tb+nC+X] 376 where -P <= X <= Q. 378 4.2.2.2. Grace Periods 380 Besides the stated time scheduling, a user may want to have some 381 grace periods (short for graceful time periods) for each or some of 382 the time intervals for the LSP. Two grace periods may be configured 383 for a time interval. One is the grace period before the time 384 interval, called grace-before, which extends the lifetime of the LSP 385 for grace-before (such as 30 seconds) before the time interval. The 386 other is the one after the time interval, called grace-after, which 387 extends the lifetime of the LSP for grace-after (such as 60 seconds) 388 after the time interval. 390 When an LSP is configured with a simple time interval such as [Ta, 391 Tb] with grace periods such as grace-before GB and grace-after GA, a 392 path is computed such that the path satisfies the constraints for the 393 LSP in the time period from Ta to Tb. The LSP along the path is set 394 up to carry traffic in the time period from (Ta-GB) to (Tb+GA). 395 During grace periods from (Ta-GB) to Ta and from Tb to (Tb+GA), the 396 LSP is up to carry traffic (maybe in best effort). 398 4.3. Scheduled LSP creation 400 In order to realize PCC-Initiated scheduled LSPs in a centralized 401 network environment, a PCC has to separate the setup of an LSP into 402 two steps. The first step is to request/delegate and get an LSP but 403 not signal it over the network. The second step is to signal the 404 scheduled LSP over the LSRs (Label Switching Router) at its starting 405 time. 407 For PCC-Initiated scheduled LSPs, a PCC can delegate the scheduled 408 LSP by sending a path computation report (PCRpt) message by including 409 its demanded resources with the scheduling information to a stateful 410 PCE. Note the PCC MAY use the PCReq/PCRep with scheduling 411 information before delegating. 413 Upon receiving the delegation via PCRpt message, the stateful PCE 414 computes the path for the scheduled LSP per its starting time and 415 duration based on the network resource availability stored in 416 scheduled TED (see Section 4.1). 418 The stateful PCE will send a PCUpd message with the scheduled path 419 information as well as the scheduled resource information for the 420 scheduled LSP to the PCC. The PCE SHOULD add the scheduled LSP into 421 its scheduled LSP-DB and update its scheduled TED. 423 For PCE-Initiated Scheduled LSP, the stateful PCE can compute a path 424 for the scheduled LSP per requests from network management systems 425 automatically based on the network resource availability in the 426 scheduled TED, send a PCInitiate message with the path information 427 back to the PCC. Based on the local policy, the PCInitiate message 428 could be sent immediately to ask PCC to create a scheduled LSP (as 429 per this document) or the PCInitiate message could be sent at the 430 start time to the PCC to create a normal LSP (as per [RFC8281]). 432 For both PCC-Initiated and PCE-Initiated Scheduled LSPs: 434 o The stateful PCE is required to update its local scheduled LSP-DB 435 and scheduled TED with the scheduled LSP. Besides, it shall send 436 a PCRpt message with the scheduled LSP to other PCEs within the 437 network, so as to achieve the scheduling traffic engineering 438 information synchronization. 440 o Upon receiving the PCUpd message or PCInitiate message for the 441 scheduled LSP from PCEs with a found path, the PCC knows that it 442 is a scheduled path for the LSP and does not trigger signaling for 443 the LSP setup on LSRs immediately. 445 o The stateful PCE can update the Scheduled LSP parameters on any 446 network events using the PCUpd message to PCC. These changes are 447 also synchronized to other PCEs. 449 o Based on the configuration (and the C flag in scheduled TLVs), 450 when it is time (i.e., at the start time) for the LSP to be set 451 up, either the PCC triggers the LSP to be signaled or the 452 delegated PCE sends a PCUpd message to the head end LSR providing 453 the updated path to be signaled (with A flag set to indicate LSP 454 activation). 456 4.4. Scheduled LSP Modifications 458 After a scheduled LSP is configured, a user may change its parameters 459 including the requested time as well as the bandwidth. 461 In PCC-Initiated case, the PCC can send a PCRpt message for the 462 scheduled LSP with updated parameters as well as scheduled 463 information included in the SCHED-LSP-ATTRIBUTE TLV (see 464 Section 5.2.1) or SCHED-PD-LSP-ATTRIBUTE TLV (see Section 5.2.2) 465 carried in the LSP Object. The PCE would take the updated resources 466 and schedule into considerations and update the new path for the 467 scheduled LSP to the PCC as well as synchronize to other PCEs in the 468 network. In case path cannot be set based on new requirements, the 469 previous LSP will not be impacted and the same should be conveyed by 470 the use of empty ERO in the PCEP messages. 472 In PCE-Initiated case, the Stateful PCE would recompute the path 473 based on updated parameters as well as scheduled information. In 474 case it has already conveyed to the PCC this information by sending a 475 PCInitiate message, it should update the path and other scheduling 476 and resource information by sending a PCUpd message. 478 4.5. Scheduled LSP activation and deletion 480 In PCC-Initiated case, based on the configuration (and the C flag in 481 scheduled TLVs), when it is time (i.e., at the start time) for the 482 LSP to be set up, either the PCC triggers the LSP to be signaled or 483 the delegated PCE sends a PCUpd message to the head end LSR providing 484 the updated path to be signaled (with A flag set to indicate LSP 485 activation). The PCC would report the status of the active LSP as 486 per the procedures in [RFC8231] and at this time the LSP MUST be 487 considered as part of the LSP-DB. The A flag MUST be set in the 488 scheduled TLVs to indicate that the LSP is active now. After the 489 scheduled duration expires, based on the C flag, the PCC triggers the 490 LSP deletion on itself or the delegated PCE sends a PCUpd message to 491 the PCC to delete the LSP as per the procedures in [RFC8231]. 493 In PCE-Initiated case, based on the local policy, if the scheduled 494 LSP is already conveyed to the PCC at the time of creation, the 495 handling of LSP activation and deletion is handled in the same way as 496 PCC-Initiated case as per the setting of C flag. Otherwise, the PCE 497 would send the PCInitiate message at the start time to the PCC to 498 create a normal LSP without the scheduled TLVs and remove the LSP 499 after the duration expires as per [RFC8281]. 501 5. PCEP Objects and TLVs 503 5.1. Stateful PCE Capability TLV 505 After a PCEP session has been established, a PCC and a PCE indicates 506 its ability to support LSP scheduling during the PCEP session 507 establishment phase. For a multiple-PCE environment, the PCEs should 508 also establish PCEP session and indicate its ability to support LSP 509 scheduling among PCEP peers. The Open Object in the Open message 510 contains the STATEFUL-PCE-CAPABILITY TLV defined in [RFC8231]. Note 511 that the STATEFUL-PCE-CAPABILITY TLV is defined in [RFC8231] and 512 updated in [RFC8281] and [RFC8232]". In this document, we define a 513 new flag bit B (SCHED-LSP-CAPABLITY) flag for the STATEFUL-PCE- 514 CAPABILITY TLV to indicate the support of LSP scheduling and another 515 flag bit PD (PD-LSP-CAPABLITY) to indicate the support of LSP 516 periodical scheduling. 518 B (LSP-SCHEDULING-CAPABILITY - 1 bit) [Bit Position - TBD3]: If set 519 to 1 by a PCC, the B Flag indicates that the PCC allows LSP 520 scheduling; if set to 1 by a PCE, the B Flag indicates that the 521 PCE is capable of LSP scheduling. The B bit MUST be set by both 522 PCEP peers in order to support LSP scheduling for path 523 computation. 525 PD (PD-LSP-CAPABLITY - 1 bit): [Bit Position - TBD4] If set to 1 by 526 a PCC, the PD Flag indicates that the PCC allows LSP scheduling 527 periodically; if set to 1 by a PCE, the PD Flag indicates that the 528 PCE is capable of periodical LSP scheduling. The PD bit MUST be 529 set by both PCEP peers in order to support periodical LSP 530 scheduling for path computation. Setting PD bit requires setting 531 B bit as specified in 5.2.2. Without setting B which indicates 532 basic capability of LSP scheduling, the advanced capability 533 indicated by Setting PD bit (capability of periodical LSP 534 scheduling) could not be achieved. 536 5.2. LSP Object 538 The LSP object is defined in [RFC8231]. This document adds an 539 optional SCHED-LSP-ATTRIBUTE TLV for normal LSP scheduling and an 540 optional SCHED-PD-LSP-ATTRIBUTE TLV for periodical LSP scheduling. 542 The presence of SCHED-LSP-ATTRIBUTE TLV in the LSP object indicates 543 that this LSP is requesting scheduled parameters while the SCHED-PD- 544 LSP-ATTRIBUTE TLV indicates that this scheduled LSP is periodical. 545 The scheduled LSP attribute TLV MUST be present in LSP Object for 546 each scheduled LSP carried in the PCEP messages. For periodical 547 LSPs, the SCHED-PD-LSP-ATTRIBUTE TLV can be used in LSP Object for 548 each periodic scheduled LSP carried in the PCEP messages. 550 Only one of these TLV SHOULD be present in the LSP object. In case 551 more than one scheduling TLV is found, the first instance is 552 processed and others ignored. 554 5.2.1. SCHED-LSP-ATTRIBUTE TLV 556 The SCHED-LSP-ATTRIBUTE TLV MAY be included as an optional TLV within 557 the LSP object for LSP scheduling for the requesting traffic service. 559 This TLV MUST NOT be included unless both PCEP peers have set the B 560 (LSP-SCHEDULING-CAPABILITY bit) in STATEFUL-PCE-CAPABILITY TLV 561 carried in the Open message. 563 The format of the SCHED-LSP-ATTRIBUTE TLV is shown in Figure 1. 565 0 1 2 3 566 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 1 567 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 568 | Type (TBD1) | Length | 569 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 570 | Flags |R|C|A|G| Reserved (0) | 571 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 572 | Start-Time | 573 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 574 | Duration | 575 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 576 | GrB / Elastic-Lower-Bound | GrA / Elastic-Upper-Bound | 577 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 579 Figure 1: SCHED-LSP-ATTRIBUTE TLV 581 The type of the TLV is [TBD1] and the TLV has a fixed length of 20 582 octets. 584 The fields in the format are: 586 Flags (8 bits): Following flags are defined in this document 588 R (1 bit): Set to 1 to indicate the Start-Time is a relative 589 time, which is the number of seconds from the current time. It 590 is necessary to synchronize the clocks of the PCEs and PCCs 591 when relative time is used. When the transmission delay from a 592 PCE or PCC to another PCE or PCC is too big such as greater 593 than 1 second, the scheduling interval represented is not 594 accurate if the delay is not considered. Set to 0 to indicate 595 that the 32-bit Start-Time is an absolute time, which is the 596 number of seconds since the epoch. The epoch is 1 January 1970 597 at 00:00 UTC. It wraps around every 2^32 seconds, which is 598 roughly 136 years. The next wraparound will occur in the year 599 2106. After the wraparound, the value of the 32-bit Start-Time 600 is the number of seconds from the time of wraparound because 601 the Start-Time is always a future time. Before the wraparound 602 and within a constant RANGE-START-TIME to reach the wraparound, 603 if the time at which the LSP is to be activated is after the 604 wraparound, the time is represented by the number of seconds 605 from the time of wraparound in the 32-bit Start-Time. RANGE- 606 START-TIME = 2*365*86400 seconds (about 2 years). 608 C (1 bit): Set to 1 to indicate the PCC is responsible to setup 609 and remove the scheduled LSP based on the Start-Time and 610 duration. 612 A (1 bit): Set to 1 to indicate the scheduled LSP has been 613 activated and should be considered as part of LSP-DB (instead 614 of Scheduled LSP-DB). 616 G (1 bit): Set to 1 to indicate the Grace period is included; set 617 to 0 indicate the elastic range is included. 619 Reserved (24 bits): This field MUST be set to zero on transmission 620 and MUST be ignored on receipt. 622 Start-Time (32 bits): This value in seconds, indicates when the 623 scheduled LSP is used to carry traffic and the corresponding LSP 624 must be setup and activated. Value of 0 MUST NOT be used in 625 Start-Time. Note that the transmission delay SHOULD be considered 626 when R=1 and the value of Start-Time is small. 628 Duration (32 bits): The value in seconds, indicates the duration 629 that the LSP is undertaken by a traffic flow and the corresponding 630 LSP must be up to carry traffic. At the expiry of this duration, 631 the LSP is torn down and deleted. Value of 0 MUST NOT be used in 632 Duration since it does not make any sense. The value of Duration 633 SHOULD be greater than a constant MINIMUM-DURATION seconds, where 634 MINIMUM-DURATION is 5. 636 The Start-Time indicates a time at or before which the scheduled LSP 637 must be set up. The value of the Start-Time represents the number of 638 seconds since the epoch when R bit is set to 0. When R bit is set to 639 1, it represents the number of seconds from the current time. 641 In addition, it contains an non zero grace-before and grace-after if 642 grace periods are configured. It includes an non zero elastic range 643 lower bound and upper bound if there is an elastic range configured. 644 A TLV can configure a non-zero grace period or elastic range, but it 645 MUST NOT provide both for an LSP. 647 o GrB (Grace-Before -16 bits): The grace period time length in 648 seconds before the starting time. 650 o GrA (Grace-After -16 bits): The grace period time length in 651 seconds after time interval [starting time, starting time + 652 duration]. 654 o Elastic-Lower-Bound (16 bits): The maximum amount of time in 655 seconds that time interval can shift to lower/left. 657 o Elastic-Upper-Bound (16 bits): The maximum amount of time in 658 seconds that time interval can shift to upper/right. 660 5.2.2. SCHED-PD-LSP-ATTRIBUTE TLV 662 The periodical LSP is a special case of LSP scheduling. The traffic 663 service happens in a series of repeated time intervals. The SCHED- 664 PD-LSP-ATTRIBUTE TLV can be included as an optional TLV within the 665 LSP object for this periodical LSP scheduling. 667 This TLV MUST NOT be included unless both PCEP peers have set the B 668 (LSP-SCHEDULING-CAPABILITY bit) and PD (PD-LSP-CAPABLITY bit) in 669 STATEFUL-PCE-CAPABILITY TLV carried in open message. 671 The format of the SCHED-PD-LSP-ATTRIBUTE TLV is shown in Figure 2. 673 0 1 2 3 674 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 1 675 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 676 | Type (TBD2) | Length | 677 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 678 | Flags |R|C|A| Opt | NR | Reserved (0) | 679 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 680 | Start-Time | 681 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 682 | Duration | 683 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 684 | Repeat-time-length | 685 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 686 | GrB / Elastic-Lower-Bound | GrA / Elastic-Upper-Bound | 687 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 689 Figure 2: SCHED-PD-LSP-ATTRIBUTE TLV 691 The type of the TLV is [TBD2] and the TLV has a fixed length of 24 692 octets. The description, format and meaning of the Flags (R, C and A 693 bit), Start-Time, Duration, GrB, GrA, Elastic-Lower-Bound and 694 Elastic-Upper-Bound fields remains same as SCHED-LSP-ATTRIBUTE TLV. 696 The following fields are new : 698 Opt: (4 bits) Indicates options to repeat. A new registry "Opt" 699 under SCHED-PD-LSP-ATTRIBUTE is created. When a PCE receives a 700 TLV with a Opt value not defined, it does not compute any path for 701 the LSP. It generates a PCEP Error (PCErr) with a PCEP-ERROR 702 object having Error-type = 4 (Not supported object) and Error- 703 value = 4 (Unsupported parameter). 705 Options = 1: repeat every day; 707 Options = 2: repeat every week; 709 Options = 3: repeat every month; 711 Options = 4: repeat every year; 713 Options = 5: repeat every Repeat-time-length. 715 NR: (12 bits) The number of repeats. In each of repeats, LSP 716 carries traffic. 718 Reserved (8 bits): This field MUST be set to zero on transmission 719 and MUST be ignored on receipt. 721 Repeat-time-length: (32 bits) The time in seconds between the start- 722 time of one repetition and the start-time of the next repetition. 724 6. The PCEP Messages 726 6.1. The PCRpt Message 728 Path Computation State Report (PCRpt) is a PCEP message sent by a PCC 729 to a PCE to report the status of one or more LSPs as per [RFC8231]. 730 Each LSP State Report in a PCRpt message contains the actual LSP's 731 path, bandwidth, operational and administrative status, etc. An LSP 732 Status Report carried on a PCRpt message is also used in delegation 733 or revocation of control of an LSP to/from a PCE. In case of 734 scheduled LSP, the scheduled TLVs MUST be carried in the LSP object 735 and the ERO conveys the intended path for the scheduled LSP. The 736 scheduled LSP MUST be delegated to a PCE. This message is also used 737 to synchronize the scheduled LSPs to other PCE as described in 738 [RFC8231] 740 6.2. The PCUpd Message 742 Path Computation Update Request (PCUpd) is a PCEP message sent by a 743 PCE to a PCC to update LSP parameters, on one or more LSPs as per 744 [RFC8231]. Each LSP Update Request on a PCUpd message contains all 745 LSP parameters that a PCE wishes to be set for a given LSP. In case 746 of scheduled LSP, the scheduled TLVs MUST be carried in the LSP 747 object and the ERO conveys the intended path for the scheduled LSP. 748 In case no path can be found, an empty ERO is used. The A bit is 749 used in PCUpd message to indicate the activation of the scheduled LSP 750 in case the PCE is responsible for the activation (as per the C bit). 752 6.3. The PCInitiate Message 754 An LSP Initiate Request (PCInitiate) message is a PCEP message sent 755 by a PCE to a PCC to trigger LSP instantiation or deletion as per 756 [RFC8281]. In case of scheduled LSP, based on the local policy, PCE 757 MAY convey the scheduled LSP to the PCC by including the scheduled 758 TLVs in the LSP object. Or the PCE would initiate the LSP only at 759 the start time of the scheduled LSP as per the [RFC8281] without the 760 use of scheduled TLVs. 762 6.4. The PCReq message 764 The Path Computation Request (PCReq) message is a PCEP message sent 765 by a PCC to a PCE to request a path computation [RFC5440] and it may 766 contain the LSP object [RFC8231] to identify the LSP for which the 767 path computation is requested. In case of scheduled LSP, the 768 scheduled TLVs MUST be carried in the LSP object in PCReq message to 769 request the path computation based on scheduled TED and LSP-DB. A 770 PCC MAY use PCReq message to obtain the scheduled path before 771 delegating the LSP. 773 6.5. The PCRep Message 775 The Path Computation Reply (PCRep) message is a PCEP message sent by 776 a PCE to a PCC in reply to a path computation request [RFC5440] and 777 it may contain the LSP object [RFC8231] to identify the LSP for which 778 the path is computed. A PCRep message can contain either a set of 779 computed paths if the request can be satisfied, or a negative reply 780 if not. The negative reply may indicate the reason why no path could 781 be found. In case of scheduled LSP, the scheduled TLVs MUST be 782 carried in the LSP object in PCRep message to indicate the path 783 computation based on scheduled TED and LSP-DB. A PCC and PCE MAY use 784 PCReq and PCRep message to obtain the scheduled path before 785 delegating the LSP. 787 6.6. The PCErr Message 789 The Path Computation Error (PCErr) message is a PCEP message as 790 described in [RFC5440] for error reporting. The current document 791 defines new error values for several error types to cover failures 792 specific to scheduling and reuse the applicable error types and error 793 values of [RFC5440] and [RFC8231] wherever appropriate. 795 The PCEP extensions for scheduling MUST NOT be used if one or both 796 PCEP speakers have not set the corresponding bits in the STATEFUL- 797 PCE-CAPABILITY TLV in their respective OPEN message. If the PCEP 798 speaker supports the extensions of this specification but did not 799 advertise this capability, then upon receipt of LSP object with the 800 scheduled TLV, it MUST generate a PCEP Error (PCErr) with Error- 801 type=19 (Invalid Operation) and error-value TBD6 (Attempted LSP 802 Scheduling if the scheduling capability was not advertised), and it 803 SHOULD ignore the TLV. As per Section 7.1 of [RFC5440], a legacy 804 PCEP implementation that does not understand this specification, 805 would consider the scheduled TLVs as unknown and ignore them. 807 If the PCC decides that the scheduling parameters proposed in the 808 PCUpd/PCInitiate message are unacceptable, it MUST report this error 809 by including the LSP-ERROR-CODE TLV (Section 7.3.3) with LSP error- 810 value="Unacceptable parameters" in the LSP object (with scheduled 811 TLVs) in the PCRpt message to the PCE. 813 The scheduled TLVs MUST be included in the LSP object for the 814 scheduled LSPs, if the TLV is missing, the receiving PCEP speaker 815 MUST send a PCErr message with Error-type=6 (Mandatory Object 816 missing) and Error-value TBD5 (Scheduled TLV missing). 818 7. Implementation Status 820 [NOTE TO RFC EDITOR : This whole section and the reference to RFC 821 7942 is to be removed before publication as an RFC] 823 This section records the status of known implementations of the 824 protocol defined by this specification at the time of posting of this 825 Internet-Draft, and is based on a proposal described in [RFC7942]. 826 The description of implementations in this section is intended to 827 assist the IETF in its decision processes in progressing drafts to 828 RFCs. Please note that the listing of any individual implementation 829 here does not imply endorsement by the IETF. Furthermore, no effort 830 has been spent to verify the information presented here that was 831 supplied by IETF contributors. This is not intended as, and must not 832 be construed to be, a catalog of available implementations or their 833 features. Readers are advised to note that other implementations may 834 exist. 836 According to [RFC7942], "this will allow reviewers and working groups 837 to assign due consideration to documents that have the benefit of 838 running code, which may serve as evidence of valuable experimentation 839 and feedback that have made the implemented protocols more mature. 840 It is up to the individual working groups to use this information as 841 they see fit". 843 At the time of posting the -09 version of this document, there are no 844 known implementations of this mechanism. It is believed that two 845 vendors/organizations are considering prototype implementations, but 846 these plans are too vague to make any further assertions. 848 8. Security Considerations 850 This document defines LSP-SCHEDULING-CAPABILITY TLV and SCHED-LSP- 851 ATTRIBUTE TLV, the security considerations discussed in [RFC5440], 852 [RFC8231], and [RFC8281] continue to apply. In some deployments the 853 scheduling information could provide details about the network 854 operations that could be deemed as extra sensitive. Additionally, 855 snooping of PCEP messages with such data or using PCEP messages for 856 network reconnaissance may give an attacker sensitive information 857 about the operations of the network. A single PCEP message can now 858 instruct a PCC to set up and tear down an LSP every second for a 859 number of times. That single message could have a significant effect 860 on the network. Thus, such deployment should employ suitable PCEP 861 security mechanisms like TCP Authentication Option (TCP-AO) [RFC5925] 862 or [RFC8253]. The procedure based on Transport Layer Security (TLS) 863 in [RFC8253] is considered a security enhancement and thus is much 864 better suited for the sensitive information. PCCs may also need to 865 apply some form of rate limit to the processing of scheduled LSPs. 867 9. Manageability Consideration 869 9.1. Control of Function and Policy 871 The LSP-Scheduling feature MUST BE controlled per tunnel by the 872 active stateful PCE, the values for parameters like starting time, 873 duration SHOULD BE configurable by customer applications and based on 874 the local policy at PCE. The suggested default values for starting 875 time and duration are one day in seconds from the current time and 876 one year in seconds respectively. One day has 86,400 seconds. One 877 year has 31,536,000 seconds. 879 When configuring the parameters about time, a user SHOULD consider 880 leap-years and leap-seconds. 882 9.2. Information and Data Models 884 An implementation SHOULD allow the operator to view the capability 885 defined in this document. To serve this purpose, the PCEP YANG 886 module [I-D.ietf-pce-pcep-yang] could be extended. 888 9.3. Liveness Detection and Monitoring 890 Mechanisms defined in this document do not imply any new liveness 891 detection and monitoring requirements in addition to those already 892 listed in [RFC5440]. 894 9.4. Verify Correct Operations 896 Mechanisms defined in this document do not imply any new operation 897 verification requirements in addition to those already listed in 898 [RFC5440]. 900 9.5. Requirements On Other Protocols 902 Mechanisms defined in this document do not imply any new requirements 903 on other protocols. 905 9.6. Impact On Network Operations 907 Mechanisms defined in this document do not have any impact on network 908 operations in addition to those already listed in [RFC5440]. 910 10. IANA Considerations 912 10.1. PCEP TLV Type Indicators 914 This document defines the following new PCEP TLVs. IANA maintains a 915 sub-registry "PCEP TLV Type Indicators" in the "Path Computation 916 Element Protocol (PCEP) Numbers" registry. IANA is requested to make 917 the following allocations from this sub-registry. 919 Value Meaning Reference 920 TBD1 SCHED-LSP-ATTRIBUTE This document 921 TBD2 SCHED-PD-LSP-ATTRIBUTE This document 923 10.1.1. Opt Field in SCHED-PD-LSP-ATTRIBUTE TLV 925 IANA is requested to create and maintain a new sub-registry named 926 "SCHED-PD-LSP-ATTRIBUTE TLV Opt field" within the "Path Computation 927 Element Protocol (PCEP) Numbers" registry. Initial values for the 928 sub-registry are given below. New values are assigned by Standards 929 Action [RFC8126]. 931 Value Name Reference 932 ----- ---- ---------- 933 0 Reserved 934 1 REPEAT-EVERY-DAY This document 935 2 REPEAT-EVERY-WEEK This document 936 3 REPEAT-EVERY-MONTH This document 937 4 REPEAT-EVERY-YEAR This document 938 5 REPEAT-EVERY-REPEAT-TIME-LENGTH This document 939 6-14 Unassigned 940 15 Reserved 942 10.1.2. Schedule TLVs Flag Field 944 IANA is requested to create a new sub-registry, named "Schedule TLVs 945 Flag Field", within the "Path Computation Element Protocol (PCEP) 946 Numbers" registry. New values are assigned by Standards Action 947 [RFC8126]. Each bit should be tracked with the following qualities: 949 o Bit number (counting from bit 0 as the most significant bit) 951 o Capability description 953 o Defining RFC 955 The following values are defined in this document: 957 Bit Description Reference 958 0-3 Unassigned 959 4 R-bit This document 960 5 C-bit This document 961 6 A-bit This document 962 7 G-bit This document 964 10.2. STATEFUL-PCE-CAPABILITY TLV Flag field 966 This document defines new bits in the Flags field in the STATEFUL- 967 PCE-CAPABILITY TLV in the OPEN object. IANA maintains a sub-registry 968 "STATEFUL-PCE-CAPABILITY TLV Flag Field" in the "Path Computation 969 Element Protocol (PCEP) Numbers" registry. IANA is requested to make 970 the following allocations from this sub-registry. 972 The following values are defined in this document: 974 Bit Description Reference 975 TBD3 LSP-SCHEDULING-CAPABILITY (B-bit) This document 976 TBD4 PD-LSP-CAPABLITY (PD-bit) This document 978 10.3. PCEP-Error Object 980 IANA is requested to allocate the following new error types to the 981 existing error values within the "PCEP-ERROR Object Error Types and 982 Values" subregistry of the "Path Computation Element Protocol (PCEP) 983 Numbers" registry: 985 Error-Type Meaning 986 6 Mandatory Object missing 988 Error-value 989 TBD5: Scheduled TLV missing 991 19 Invalid Operation 993 Error-value 994 TBD6: Attempted LSP Scheduling if the scheduling 995 capability was not advertised 997 29 Path computation failure 999 Error-value 1000 TBD7: Constraints could not be met for some intervals 1002 11. Acknowledgments 1004 The authors of this document would also like to thank Rafal Szarecki, 1005 Adrian Farrel, Cyril Margaria for the review and comments. 1007 12. References 1009 12.1. Normative References 1011 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1012 Requirement Levels", BCP 14, RFC 2119, 1013 DOI 10.17487/RFC2119, March 1997, 1014 . 1016 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 1017 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 1018 DOI 10.17487/RFC5440, March 2009, 1019 . 1021 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1022 Writing an IANA Considerations Section in RFCs", BCP 26, 1023 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1024 . 1026 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1027 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1028 May 2017, . 1030 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 1031 Computation Element Communication Protocol (PCEP) 1032 Extensions for Stateful PCE", RFC 8231, 1033 DOI 10.17487/RFC8231, September 2017, 1034 . 1036 [RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 1037 and D. Dhody, "Optimizations of Label Switched Path State 1038 Synchronization Procedures for a Stateful PCE", RFC 8232, 1039 DOI 10.17487/RFC8232, September 2017, 1040 . 1042 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 1043 Computation Element Communication Protocol (PCEP) 1044 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 1045 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 1046 . 1048 12.2. Informative References 1050 [I-D.ietf-detnet-architecture] 1051 Finn, N., Thubert, P., Varga, B., and J. Farkas, 1052 "Deterministic Networking Architecture", draft-ietf- 1053 detnet-architecture-13 (work in progress), May 2019. 1055 [I-D.ietf-pce-pcep-yang] 1056 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 1057 YANG Data Model for Path Computation Element 1058 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 1059 yang-13 (work in progress), October 2019. 1061 [I-D.litkowski-pce-state-sync] 1062 Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter 1063 Stateful Path Computation Element (PCE) Communication 1064 Procedures.", draft-litkowski-pce-state-sync-07 (work in 1065 progress), January 2020. 1067 [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP 1068 Authentication Option", RFC 5925, DOI 10.17487/RFC5925, 1069 June 2010, . 1071 [RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path 1072 Computation Element Architecture", RFC 7399, 1073 DOI 10.17487/RFC7399, October 2014, 1074 . 1076 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 1077 Code: The Implementation Status Section", BCP 205, 1078 RFC 7942, DOI 10.17487/RFC7942, July 2016, 1079 . 1081 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 1082 Stateful Path Computation Element (PCE)", RFC 8051, 1083 DOI 10.17487/RFC8051, January 2017, 1084 . 1086 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 1087 "PCEPS: Usage of TLS to Provide a Secure Transport for the 1088 Path Computation Element Communication Protocol (PCEP)", 1089 RFC 8253, DOI 10.17487/RFC8253, October 2017, 1090 . 1092 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1093 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1094 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1095 July 2018, . 1097 [RFC8413] Zhuang, Y., Wu, Q., Chen, H., and A. Farrel, "Framework 1098 for Scheduled Use of Resources", RFC 8413, 1099 DOI 10.17487/RFC8413, July 2018, 1100 . 1102 Appendix A. Contributors Addresses 1104 Dhruv Dhody 1105 Huawei 1106 Divyashree Techno Park, Whitefield 1107 Bangalore, Karnataka 560066 1108 India 1110 Email: dhruv.ietf@gmail.com 1112 Xufeng Liu 1113 Ericsson 1114 USA 1115 Email: xliu@kuatrotech.com 1117 Mehmet Toy 1118 Verizon 1119 USA 1120 Email: mehmet.toy@verizon.com 1122 Vic Liu 1123 China Mobile 1124 No.32 Xuanwumen West Street, Xicheng District 1125 Beijing, 100053 1126 China 1127 Email: liu.cmri@gmail.com 1129 Lei Liu 1130 Fujitsu 1131 USA 1132 Email: lliu@us.fujitsu.com 1134 Khuzema Pithewan 1135 Infinera 1136 Email: kpithewan@infinera.com 1138 Zitao Wang 1139 Huawei 1140 101 Software Avenue, Yuhua District 1141 Nanjing, Jiangsu 210012 1142 China 1144 Email: wangzitao@huawei.com 1146 Xian Zhang 1147 Huawei Technologies 1148 Research Area F3-1B, 1149 Huawei Industrial Base, 1150 Shenzhen, 518129, China 1152 Email: zhang.xian@huawei.com 1154 Authors' Addresses 1156 Huaimo Chen (editor) 1157 Futurewei 1158 Boston, MA 1159 USA 1161 Email: huaimo.chen@futurewei.com 1163 Yan Zhuang (editor) 1164 Huawei 1165 101 Software Avenue, Yuhua District 1166 Nanjing, Jiangsu 210012 1167 China 1169 Email: zhuangyan.zhuang@huawei.com 1170 Qin Wu 1171 Huawei 1172 101 Software Avenue, Yuhua District 1173 Nanjing, Jiangsu 210012 1174 China 1176 Email: bill.wu@huawei.com 1178 Daniele Ceccarelli 1179 Ericsson 1180 Via A. Negrone 1/A 1181 Genova - Sestri Ponente 1182 Italy 1184 Email: daniele.ceccarelli@ericsson.com