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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 353, but not defined == Missing Reference: 'Tb' is mentioned on line 353, but not defined == Missing Reference: 'TBD1' is mentioned on line 573, but not defined == Missing Reference: 'TBD2' is mentioned on line 671, but not defined == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-13 == Outdated reference: A later version (-10) exists of draft-litkowski-pce-state-sync-07 Summary: 0 errors (**), 0 flaws (~~), 7 warnings (==), 1 comment (--).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: September 24, 2020 Q. Wu 6 Huawei 7 D. Ceccarelli 8 Ericsson 9 March 23, 2020 11 PCEP Extensions for LSP scheduling with stateful PCE 12 draft-ietf-pce-stateful-pce-lsp-scheduling-13 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 September 24, 2020. 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 . . . . . . . . . . 10 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 . . . . . . . . . . . . . 14 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 . . . . . . . . . . . . . . . . . 16 78 6.4. The PCReq message . . . . . . . . . . . . . . . . . . . . 16 79 6.5. The PCRep Message . . . . . . . . . . . . . . . . . . . . 17 80 6.6. The PCErr Message . . . . . . . . . . . . . . . . . . . . 17 81 7. Implementation Status . . . . . . . . . . . . . . . . . . . . 18 82 8. Security Considerations . . . . . . . . . . . . . . . . . . . 18 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 . . . . . . . . . . . . . . . . 19 88 9.5. Requirements On Other Protocols . . . . . . . . . . . . . 19 89 9.6. Impact On Network Operations . . . . . . . . . . . . . . 19 90 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 91 10.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 19 92 10.1.1. Opt Field in SCHED-PD-LSP-ATTRIBUTE TLV . . . . . . 20 93 10.1.2. Schedule TLVs Flag Field . . . . . . . . . . . . . . 20 94 10.2. STATEFUL-PCE-CAPABILITY TLV Flag field . . . . . . . . . 21 95 10.3. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 21 96 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21 97 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 98 12.1. Normative References . . . . . . . . . . . . . . . . . . 21 99 12.2. Informative References . . . . . . . . . . . . . . . . . 22 100 Appendix A. Contributors Addresses . . . . . . . . . . . . . . . 23 101 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 network usage since the established paths 123 exclude the possibility of being used by other services even when 124 they are not used for undertaking any service. [RFC8413] then 125 provides a framework that describes and discusses the problem, and 126 defines an appropriate architecture for the scheduled reservation of 127 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 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], so as to provide more efficient network resource usage for 138 traffic engineering, which hasn't been solved yet. Also, for 139 deterministic networks [I-D.ietf-detnet-architecture], the scheduled 140 LSP or 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 data base. 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 computes a path 262 for the LSP with the scheduling information and update to the PCC as 263 per 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. In case of former SCHED- 290 LSP-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 the scheduling 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 represents Scheduling LSP every time 321 interval. It has a scheduling duration such as [Ta, Tb], a number of 322 repeats such as 10 (repeats 10 times), and a repeat cycle/time 323 interval such as a week (repeats every week). The scheduling 324 interval: "[Ta, Tb] repeats n times with repeat cycle C" represents 325 n+1 scheduling intervals as follows: 327 [Ta, Tb], [Ta+C, Tb+C], [Ta+2C, Tb+2C], ..., [Ta+nC, Tb+nC] 329 When an LSP is configured with a scheduling interval such as "[Ta, 330 Tb] repeats 10 times with a repeat cycle a week" (representing 11 331 scheduling intervals), a path satisfying the constraints for the LSP 332 in each of the scheduling intervals represented by the periodical 333 scheduling interval is computed and the LSP along the path is set up 334 to carry traffic in each of the scheduling intervals. 336 4.2.2.1. Elastic Time LSP Scheduling 338 In addition to the basic LSP scheduling at an arbitrary time period, 339 another option is elastic time intervals, which is represented as 340 within -P and Q, where P and Q is an amount of time such as 300 341 seconds. P is called elastic range lower bound and Q is called 342 elastic range upper bound. 344 For a simple time interval such as [Ta, Tb] with an elastic range, 345 elastic time interval: "[Ta, Tb] within -P and Q" means a time period 346 from (Ta+X) to (Tb+X), where -P <= X <= Q. Note that both Ta and Tb 347 is shifted by the same 'X'. 349 When an LSP is configured with elastic time interval "[Ta, Tb] within 350 -P and Q", a path is computed such that the path satisfies the 351 constraints for the LSP in the time period from (Ta+X) to (Tb+X) 352 and |X| is the minimum value from 0 to max(P, Q). That is, [Ta+X, 353 Tb+X] is the time interval closest to time interval [Ta, Tb] within 354 the elastic range. The LSP along the path is set up to carry traffic 355 in the time period from (Ta+X) to (Tb+X). 357 Similarly, for a recurrent time interval with an elastic range, 358 elastic time interval: "[Ta, Tb] repeats n times with repeat cycle C 359 within -P and Q" represents n+1 simple elastic time intervals as 360 follows: 362 [Ta+X0, Tb+X0], [Ta+C+X1, Tb+C+X1], ..., [Ta+nC+Xn, Tb+nC+Xn] 363 where -P <= Xi <= Q, i = 0, 1, 2, ..., n. 365 If a user wants to keep the same repeat cycle between any two 366 adjacent time intervals, elastic time interval: "[Ta, Tb] repeats n 367 times with repeat cycle C within -P and Q SYNC" may be used, which 368 represents n+1 simple elastic time intervals as follows: 370 [Ta+X, Tb+X], [Ta+C+X, Tb+C+X], ..., [Ta+nC+X, Tb+nC+X] 371 where -P <= X <= Q. 373 4.2.2.2. Grace Periods 375 Besides the stated time scheduling, a user may want to have some 376 grace periods (short for graceful time periods) for each or some of 377 the time intervals for the LSP. Two grace periods may be configured 378 for a time interval. One is the grace period before the time 379 interval, called grace-before, which extends the lifetime of the LSP 380 for grace-before (such as 30 seconds) before the time interval. The 381 other is the one after the time interval, called grace-after, which 382 extends the lifetime of the LSP for grace-after (such as 60 seconds) 383 after the time interval. 385 When an LSP is configured with a simple time interval such as [Ta, 386 Tb] with grace periods such as grace-before GB and grace-after GA, a 387 path is computed such that the path satisfies the constraints for the 388 LSP in the time period from Ta to Tb. The LSP along the path is set 389 up to carry traffic in the time period from (Ta-GB) to (Tb+GA). 390 During grace periods from (Ta-GB) to Ta and from Tb to (Tb+GA), the 391 LSP is up to carry traffic (maybe in best effort). 393 4.3. Scheduled LSP creation 395 In order to realize PCC-Initiated scheduled LSPs in a centralized 396 network environment, a PCC has to separate the setup of an LSP into 397 two steps. The first step is to request/delegate and get an LSP but 398 not signal it over the network. The second step is to signal the 399 scheduled LSP over the LSRs (Label Switching Router) at its starting 400 time. 402 For PCC-Initiated scheduled LSPs, a PCC can delegate the scheduled 403 LSP by sending a path computation report (PCRpt) message by including 404 its demanded resources with the scheduling information to a stateful 405 PCE. Note the PCC MAY use the PCReq/PCRep with scheduling 406 information before delegating. 408 Upon receiving the delegation via PCRpt message, the stateful PCE 409 computes the path for the scheduled LSP per its starting time and 410 duration based on the network resource availability stored in 411 scheduled TED (see Section 4.1). 413 The stateful PCE will send a PCUpd message with the scheduled path 414 information as well as the scheduled resource information for the 415 scheduled LSP to the PCC. The PCE SHOULD add the scheduled LSP into 416 its scheduled LSP-DB and update its scheduled TED. 418 For PCE-Initiated Scheduled LSP, the stateful PCE can compute a path 419 for the scheduled LSP per requests from network management systems 420 automatically based on the network resource availability in the 421 scheduled TED, send a PCInitiate message with the path information 422 back to the PCC. Based on the local policy, the PCInitiate message 423 could be sent immediately to ask PCC to create a scheduled LSP (as 424 per this document) or the PCInitiate message could be sent at the 425 start time to the PCC to create a normal LSP (as per [RFC8281]). 427 In both modes: 429 o The stateful PCE is required to update its local scheduled LSP-DB 430 and scheduled TED with the scheduled LSP. Besides, it shall send 431 a PCRpt message with the scheduled LSP to other PCEs within the 432 network, so as to achieve the scheduling traffic engineering 433 information synchronization. 435 o Upon receiving the PCUpd message or PCInitiate message for the 436 scheduled LSP from PCEs with a found path, the PCC knows that it 437 is a scheduled path for the LSP and does not trigger signaling for 438 the LSP setup on LSRs immediately. 440 o The stateful PCE can update the Scheduled LSP parameters on any 441 network events using the PCUpd message to PCC. These changes are 442 also synchronized to other PCEs. 444 o Based on the configuration (and the C flag in scheduled TLVs), 445 when it is time (i.e., at the start time) for the LSP to be set 446 up, either the PCC triggers the LSP to be signaled or the 447 delegated PCE sends a PCUpd message to the head end LSR providing 448 the updated path to be signaled (with A flag set to indicate LSP 449 activation). 451 4.4. Scheduled LSP Modifications 453 After a scheduled LSP is configured, a user may change its parameters 454 including the requested time as well as the bandwidth. 456 In PCC-Initiated case, the PCC can send a PCRpt message for the 457 scheduled LSP with updated parameters as well as scheduled 458 information included in the SCHED-LSP-ATTRIBUTE TLV (see 459 Section 5.2.1) or SCHED-PD-LSP-ATTRIBUTE TLV (see Section 5.2.2) 460 carried in the LSP Object. The PCE would take the updated resources 461 and schedule into considerations and update the new path for the 462 scheduled LSP to the PCC as well as synchronize to other PCEs in the 463 network. In case path cannot be set based on new requirements the 464 same should be conveyed by the use of empty ERO in the PCEP messages. 466 In PCE-Initiated case, the Stateful PCE would recompute the path 467 based on updated parameters as well as scheduled information. In 468 case it has already conveyed to the PCC this information by sending a 469 PCInitiate message, it should update the path and other scheduling 470 and resource information by sending a PCUpd message. 472 4.5. Scheduled LSP activation and deletion 474 In PCC-Initiated case, based on the configuration (and the C flag in 475 scheduled TLVs), when it is time (i.e., at the start time) for the 476 LSP to be set up, either the PCC triggers the LSP to be signaled or 477 the delegated PCE sends a PCUpd message to the head end LSR providing 478 the updated path to be signaled (with A flag set to indicate LSP 479 activation). The PCC would report the status of the active LSP as 480 per the procedures in [RFC8231] and at this time the LSP MUST be 481 considered as part of the LSP-DB. The A flag MUST be set in the 482 scheduled TLVs to indicate that the LSP is active now. After the 483 scheduled duration expires, based on the C flag, the PCC triggers the 484 LSP deletion on itself or the delegated PCE sends a PCUpd message to 485 the PCC to delete the LSP as per the procedures in [RFC8231]. 487 In PCE-Initiated case, based on the local policy, if the scheduled 488 LSP is already conveyed to the PCC at the time of creation, the 489 handling of LSP activation and deletion is handled in the same way as 490 PCC-Initiated case as per the setting of C flag. In other case, the 491 PCE would send the PCInitiate message at the start time to the PCC to 492 create a normal LSP without the scheduled TLVs and remove the LSP 493 after the duration expires as per [RFC8281]. 495 5. PCEP Objects and TLVs 497 5.1. Stateful PCE Capability TLV 499 After a TCP connection for a PCEP session has been established, a PCC 500 and a PCE indicates its ability to support LSP scheduling during the 501 PCEP session establishment phase. For a multiple-PCE environment, 502 the PCEs should also establish PCEP session and indicate its ability 503 to support LSP scheduling among PCEP peers. The Open Object in the 504 Open message contains the STATEFUL-PCE-CAPABILITY TLV defined in 505 [RFC8231]. Note that the STATEFUL-PCE-CAPABILITY TLV is defined in 506 [RFC8231] and updated in [RFC8281] and [RFC8232]". In this document, 507 we define a new flag bit B (SCHED-LSP-CAPABLITY) flag for the 508 STATEFUL-PCE-CAPABILITY TLV to indicate the support of LSP scheduling 509 and another flag bit PD (PD-LSP-CAPABLITY) to indicate the support of 510 LSP periodical scheduling. 512 B (LSP-SCHEDULING-CAPABILITY - 1 bit) [Bit Position - TBD3]: If set 513 to 1 by a PCC, the B Flag indicates that the PCC allows LSP 514 scheduling; if set to 1 by a PCE, the B Flag indicates that the 515 PCE is capable of LSP scheduling. The B bit MUST be set by both 516 PCEP peers in order to support LSP scheduling for path 517 computation. 519 PD (PD-LSP-CAPABLITY - 1 bit): [Bit Position - TBD4] If set to 1 by 520 a PCC, the PD Flag indicates that the PCC allows LSP scheduling 521 periodically; if set to 1 by a PCE, the PD Flag indicates that the 522 PCE is capable of periodical LSP scheduling. The PD bit MUST be 523 set by both PCEP peers in order to support periodical LSP 524 scheduling for path computation. 526 5.2. LSP Object 528 The LSP object is defined in [RFC8231]. This document adds an 529 optional SCHED-LSP-ATTRIBUTE TLV for normal LSP scheduling and an 530 optional SCHED-PD-LSP-ATTRIBUTE TLV for periodical LSP scheduling. 532 The presence of SCHED-LSP-ATTRIBUTE TLV in the LSP object indicates 533 that this LSP is requesting scheduled parameters while the SCHED-PD- 534 LSP-ATTRIBUTE TLV indicates that this scheduled LSP is periodical. 535 The scheduled LSP attribute TLV MUST be present in LSP Object for 536 each scheduled LSP carried in the PCEP messages. For periodical 537 LSPs, the SCHED-PD-LSP-ATTRIBUTE TLV can be used in LSP Object for 538 each periodic scheduled LSP carried in the PCEP messages. 540 Only one of these TLV SHOULD be present in the LSP object. In case 541 more than one scheduling TLV is found, the first instance is 542 processed and others ignored. 544 5.2.1. SCHED-LSP-ATTRIBUTE TLV 546 The SCHED-LSP-ATTRIBUTE TLV MAY be included as an optional TLV within 547 the LSP object for LSP scheduling for the requesting traffic service. 549 This TLV SHOULD NOT be included unless both PCEP peers have set the B 550 (LSP-SCHEDULING-CAPABILITY bit) in STATEFUL-PCE-CAPABILITY TLV 551 carried in the Open message. 553 The format of the SCHED-LSP-ATTRIBUTE TLV is shown in Figure 1. 555 0 1 2 3 556 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 1 557 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 558 | Type (TBD1) | Length | 559 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 560 | Flags |R|C|A| Reserved (0) | 561 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 562 | Start-Time | 563 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 564 | Duration | 565 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 566 | GrB | GrA | 567 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 568 | Elastic-Lower-Bound | Elastic-Upper-Bound | 569 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 571 Figure 1: SCHED-LSP-ATTRIBUTE TLV 573 The type of the TLV is [TBD1] and the TLV has a fixed length of 20 574 octets. 576 The fields in the format are: 578 Flags (8 bits): Following flags are defined in this document 580 R (1 bit): Set to 1 to indicate the Start-Time is a relative 581 time, which is relative to the current time; set to 0 to 582 indicate that the 32-bit Start-Time is an absolute time, which 583 is the number of seconds since the epoch. The epoch is 1 584 January 1970 at 00:00 UTC. It wraps around every 2^32 seconds, 585 which is roughly 136 years. The next wraparound will occur in 586 the year 2106. After the wraparound, the value of the 32-bit 587 Start-Time is the number of seconds from the time of wraparound 588 because the Start-Time is always a future time. Just before 589 the wraparound, if the time at which the LSP is to be activated 590 is after the wraparound, the time is represented by the number 591 of seconds from the time of wraparound in the 32-bit Start- 592 Time. 594 C (1 bit): Set to 1 to indicate the PCC is responsible to setup 595 and remove the scheduled LSP based on the Start-Time and 596 duration. 598 A (1 bit): Set to 1 to indicate the scheduled LSP has been 599 activated and should be considered as part of LSP-DB (instead 600 of Scheduled LSP-DB). 602 Reserved (24 bits): This field MUST be set to zero on transmission 603 and MUST be ignored on receipt. 605 Start-Time (32 bits): This value in seconds, indicates when the 606 scheduled LSP is used to carry traffic and the corresponding LSP 607 must be setup and activated. Value of 0 MUST NOT be used in 608 Start-Time. 610 Duration (32 bits): The value in seconds, indicates the duration 611 that the LSP is undertaken by a traffic flow and the corresponding 612 LSP must be up to carry traffic. At the expiry of this duration, 613 the LSP is torn down and deleted. Value of 0 MUST NOT be used in 614 Duration since it does not make any sense. 616 The Start-Time indicates a time at or before which the scheduled LSP 617 must be set up. The value of the Start-Time represents the number of 618 seconds since the epoch when R bit is set to 0. When R bit is set to 619 1, it represents the number of seconds from the current time. 621 In addition, it contains an non zero grace-before and grace-after if 622 grace periods are configured. It includes an non zero elastic range 623 lower bound and upper bound if there is an elastic range configured. 625 o GrB (Grace-Before -16 bits): The grace period time length in 626 seconds before the starting time. 628 o GrA (Grace-After -16 bits): The grace period time length in 629 seconds after time interval [starting time, starting time + 630 duration]. 632 o Elastic-Lower-Bound (16 bits): The maximum amount of time in 633 seconds that time interval can shift to lower/left. 635 o Elastic-Upper-Bound (16 bits): The maximum amount of time in 636 seconds that time interval can shift to upper/right. 638 5.2.2. SCHED-PD-LSP-ATTRIBUTE TLV 640 The periodical LSP is a special case of LSP scheduling. The traffic 641 service happens in a series of repeated time intervals. The SCHED- 642 PD-LSP-ATTRIBUTE TLV can be included as an optional TLV within the 643 LSP object for this periodical LSP scheduling. 645 This TLV SHOULD NOT be included unless both PCEP peers have set the B 646 (LSP-SCHEDULING-CAPABILITY bit) and PD (PD-LSP-CAPABLITY bit) in 647 STATEFUL-PCE-CAPABILITY TLV carried in open message. 649 The format of the SCHED-PD-LSP-ATTRIBUTE TLV is shown in Figure 2. 651 0 1 2 3 652 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 1 653 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 654 | Type (TBD2) | Length | 655 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 656 | Flags |R|C|A| Opt | NR | Reserved (0) | 657 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 658 | Start-Time | 659 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 660 | Duration | 661 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 662 | Repeat-time-length | 663 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 664 | GrB | GrA | 665 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 666 | Elastic-Lower-Bound | Elastic-Upper-Bound | 667 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 669 Figure 2: SCHED-PD-LSP-ATTRIBUTE TLV 671 The type of the TLV is [TBD2] and the TLV has a fixed length of 24 672 octets. The description, format and meaning of the Flags (R, C and A 673 bit), Start-Time, Duration, GrB, GrA, Elastic-Lower-Bound and 674 Elastic-Upper-Bound fields remains same as SCHED-LSP-ATTRIBUTE TLV. 676 The following fields are new : 678 Opt: (4 bits) Indicates options to repeat. 680 Options = 1: repeat every day; 682 Options = 2: repeat every week; 684 Options = 3: repeat every month; 686 Options = 4: repeat every year; 688 Options = 5: repeat every Repeat-time-length. 690 NR: (12 bits) The number of repeats. In each of repeats, LSP 691 carries traffic. 693 Reserved (8 bits): This field MUST be set to zero on transmission 694 and MUST be ignored on receipt. 696 Repeat-time-length: (32 bits) The time length in seconds after which 697 LSP starts to carry traffic again for the Duration. 699 6. The PCEP Messages 701 6.1. The PCRpt Message 703 Path Computation State Report (PCRpt) is a PCEP message sent by a PCC 704 to a PCE to report the status of one or more LSPs as per [RFC8231]. 705 Each LSP State Report in a PCRpt message contains the actual LSP's 706 path, bandwidth, operational and administrative status, etc. An LSP 707 Status Report carried on a PCRpt message is also used in delegation 708 or revocation of control of an LSP to/from a PCE. In case of 709 scheduled LSP, the scheduled TLVs MUST be carried in the LSP object 710 and the ERO conveys the intended path for the scheduled LSP. The 711 scheduled LSP MUST be delegated to a PCE. This message is also used 712 to synchronize the scheduled LSPs to other PCE as described in 713 [RFC8231] 715 6.2. The PCUpd Message 717 Path Computation Update Request (PCUpd) is a PCEP message sent by a 718 PCE to a PCC to update LSP parameters, on one or more LSPs as per 719 [RFC8231]. Each LSP Update Request on a PCUpd message contains all 720 LSP parameters that a PCE wishes to be set for a given LSP. In case 721 of scheduled LSP, the scheduled TLVs MUST be carried in the LSP 722 object and the ERO conveys the intended path for the scheduled LSP. 723 In case no path can be found, an empty ERO is used. The A bit is 724 used in PCUpd message to indicate the activation of the scheduled LSP 725 in case the PCE is responsible for the activation (as per the C bit). 727 6.3. The PCInitiate Message 729 An LSP Initiate Request (PCInitiate) message is a PCEP message sent 730 by a PCE to a PCC to trigger LSP instantiation or deletion as per 731 [RFC8281]. In case of scheduled LSP, based on the local policy, PCE 732 MAY convey the scheduled LSP to the PCC by including the scheduled 733 TLVs in the LSP object. Or the PCE would initiate the LSP only at 734 the start time of the scheduled LSP as per the [RFC8281] without the 735 use of scheduled TLVs. 737 6.4. The PCReq message 739 The Path Computation Request (PCReq) message is a PCEP message sent 740 by a PCC to a PCE to request a path computation [RFC5440] and it may 741 contain the LSP object [RFC8231] to identify the LSP for which the 742 path computation is requested. In case of scheduled LSP, the 743 scheduled TLVs MUST be carried in the LSP object in PCReq message to 744 request the path computation based on scheduled TED and LSP-DB. A 745 PCC MAY use PCReq message to obtain the scheduled path before 746 delegating the LSP. 748 6.5. The PCRep Message 750 The Path Computation Reply (PCRep) message is a PCEP message sent by 751 a PCE to a PCC in reply to a path computation request [RFC5440] and 752 it may contain the LSP object [RFC8231] to identify the LSP for which 753 the path is computed. A PCRep message can contain either a set of 754 computed paths if the request can be satisfied, or a negative reply 755 if not. The negative reply may indicate the reason why no path could 756 be found. In case of scheduled LSP, the scheduled TLVs MUST be 757 carried in the LSP object in PCRep message to indicate the path 758 computation based on scheduled TED and LSP-DB. A PCC and PCE MAY use 759 PCReq and PCRep message to obtain the scheduled path before 760 delegating the LSP. 762 6.6. The PCErr Message 764 The Path Computation Error (PCErr) message is a PCEP message as 765 described in [RFC5440] for error reporting. The current document 766 defines new error values for several error types to cover failures 767 specific to scheduling and reuse the applicable error types and error 768 values of [RFC5440] and [RFC8231] wherever appropriate. 770 The PCEP extensions for scheduling MUST NOT be used if one or both 771 PCEP speakers have not set the corresponding bits in the STATEFUL- 772 PCE-CAPABILITY TLV in their respective OPEN message. If the PCEP 773 speaker supports the extensions of this specification but did not 774 advertise this capability, then upon receipt of LSP object with the 775 scheduled TLV, it MUST generate a PCEP Error (PCErr) with Error- 776 type=19 (Invalid Operation) and error-value TBD6 (Attempted LSP 777 Scheduling if the scheduling capability was not advertised), and it 778 SHOULD ignore the TLV. As per Section 7.1 of [RFC5440], a legacy 779 PCEP implementation that does not understand this specification, 780 would consider the scheduled TLVs as unknown and ignore them. 782 If the PCC decides that the scheduling parameters proposed in the 783 PCUpd/PCInitiate message are unacceptable, it MUST report this error 784 by including the LSP-ERROR-CODE TLV (Section 7.3.3) with LSP error- 785 value="Unacceptable parameters" in the LSP object (with scheduled 786 TLVs) in the PCRpt message to the PCE. 788 The scheduled TLVs MUST be included in the LSP object for the 789 scheduled LSPs, if the TLV is missing, the receiving PCEP speaker 790 MUST send a PCErr message with Error-type=6 (Mandatory Object 791 missing) and Error-value TBD5 (Scheduled TLV missing). 793 7. Implementation Status 795 [NOTE TO RFC EDITOR : This whole section and the reference to RFC 796 7942 is to be removed before publication as an RFC] 798 This section records the status of known implementations of the 799 protocol defined by this specification at the time of posting of this 800 Internet-Draft, and is based on a proposal described in [RFC7942]. 801 The description of implementations in this section is intended to 802 assist the IETF in its decision processes in progressing drafts to 803 RFCs. Please note that the listing of any individual implementation 804 here does not imply endorsement by the IETF. Furthermore, no effort 805 has been spent to verify the information presented here that was 806 supplied by IETF contributors. This is not intended as, and must not 807 be construed to be, a catalog of available implementations or their 808 features. Readers are advised to note that other implementations may 809 exist. 811 According to [RFC7942], "this will allow reviewers and working groups 812 to assign due consideration to documents that have the benefit of 813 running code, which may serve as evidence of valuable experimentation 814 and feedback that have made the implemented protocols more mature. 815 It is up to the individual working groups to use this information as 816 they see fit". 818 At the time of posting the -09 version of this document, there are no 819 known implementations of this mechanism. It is believed that two 820 vendors/organizations are considering prototype implementations, but 821 these plans are too vague to make any further assertions. 823 8. Security Considerations 825 This document defines LSP-SCHEDULING-CAPABILITY TLV and SCHED-LSP- 826 ATTRIBUTE TLV, the security considerations discussed in [RFC5440], 827 [RFC8231], and [RFC8281] continue to apply. In some deployments the 828 scheduling information could provide details about the network 829 operations that could be deemed as extra sensitive. Additionally, 830 snooping of PCEP messages with such data or using PCEP messages for 831 network reconnaissance may give an attacker sensitive information 832 about the operations of the network. A single PCEP message can now 833 instruct a PCC to set up and tear down an LSP every second for a 834 number of times. That single message could have a significant effect 835 on the network. Thus, such deployment should employ suitable PCEP 836 security mechanisms like TCP Authentication Option (TCP-AO) [RFC5925] 837 or [RFC8253]. The procedure based on Transport Layer Security (TLS) 838 in [RFC8253] is considered a security enhancement and thus is much 839 better suited for the sensitive information. PCCs may also need to 840 apply some form of rate limit to the processing of scheduled LSPs. 842 9. Manageability Consideration 844 9.1. Control of Function and Policy 846 The LSP-Scheduling feature MUST BE controlled per tunnel by the 847 active stateful PCE, the values for parameters like starting time, 848 duration SHOULD BE configurable by customer applications and based on 849 the local policy at PCE. The suggested defaut values for starting 850 time and duration are one day in seconds from the current time and 851 one year in seconds respectively. One day has 86,400 seconds. One 852 year has 31,536,000 seconds. 854 9.2. Information and Data Models 856 An implementation SHOULD allow the operator to view the capability 857 defined in this document. To serve this purpose, the PCEP YANG 858 module [I-D.ietf-pce-pcep-yang] could be extended. 860 9.3. Liveness Detection and Monitoring 862 Mechanisms defined in this document do not imply any new liveness 863 detection and monitoring requirements in addition to those already 864 listed in [RFC5440]. 866 9.4. Verify Correct Operations 868 Mechanisms defined in this document do not imply any new operation 869 verification requirements in addition to those already listed in 870 [RFC5440]. 872 9.5. Requirements On Other Protocols 874 Mechanisms defined in this document do not imply any new requirements 875 on other protocols. 877 9.6. Impact On Network Operations 879 Mechanisms defined in this document do not have any impact on network 880 operations in addition to those already listed in [RFC5440]. 882 10. IANA Considerations 884 10.1. PCEP TLV Type Indicators 886 This document defines the following new PCEP TLVs. IANA maintains a 887 sub-registry "PCEP TLV Type Indicators" in the "Path Computation 888 Element Protocol (PCEP) Numbers" registry. IANA is requested to make 889 the following allocations from this sub-registry. 891 Value Meaning Reference 892 TBD1 SCHED-LSP-ATTRIBUTE This document 893 TBD2 SCHED-PD-LSP-ATTRIBUTE This document 895 10.1.1. Opt Field in SCHED-PD-LSP-ATTRIBUTE TLV 897 IANA is requested to create and maintain a new registry "Opt" under 898 SCHED-PD-LSP-ATTRIBUTE (TLV Type: TBD2). Initial values for the 899 registry are given below. New values are assigned by Standards 900 Action [RFC8126]. 902 Value Name Reference 903 ----- ---- ---------- 904 0 Reserved 905 1 REPEAT-EVERY-DAY This document 906 2 REPEAT-EVERY-WEEK This document 907 3 REPEAT-EVERY-MONTH This document 908 4 REPEAT-EVERY-YEAR This document 909 5 REPEAT-EVERY-REPEAT-TIME-LENGTH This document 910 6-14 Unassigned 911 15 Reserved 913 10.1.2. Schedule TLVs Flag Field 915 IANA is requested to create a new sub-registry, named "Schedule TLVs 916 Flag Field", within the "Path Computation Element Protocol (PCEP) 917 Numbers" registry to manage the Flag field in the SCHED-LSP-ATTRIBUTE 918 and SCHED-PD-LSP-ATTRIBUTE TLVs. New values are assigned by 919 Standards Action [RFC8126]. Each bit should be tracked with the 920 following qualities: 922 o Bit number (counting from bit 0 as the most significant bit) 924 o Capability description 926 o Defining RFC 928 The following values are defined in this document: 930 Bit Description Reference 931 0-4 Unassigned 932 5 R-bit This document 933 6 C-bit This document 934 7 A-bit This document 936 10.2. STATEFUL-PCE-CAPABILITY TLV Flag field 938 This document defines new bits in the Flags field in the STATEFUL- 939 PCE-CAPABILITY TLV in the OPEN object. IANA maintains a sub-registry 940 "STATEFUL-PCE-CAPABILITY TLV Flag Field" in the "Path Computation 941 Element Protocol (PCEP) Numbers" registry. IANA is requested to make 942 the following allocations from this sub-registry. 944 The following values are defined in this document: 946 Bit Description Reference 947 TBD3 LSP-SCHEDULING-CAPABILITY (B-bit) This document 948 TBD4 PD-LSP-CAPABLITY (PD-bit) This document 950 10.3. PCEP-Error Object 952 IANA is requested to allocate the following new error types to the 953 existing error values within the "PCEP-ERROR Object Error Types and 954 Values" subregistry of the "Path Computation Element Protocol (PCEP) 955 Numbers" registry: 957 Error-Type Meaning 958 6 Mandatory Object missing 960 Error-value 961 TBD5: Scheduled TLV missing 963 19 Invalid Operation 965 Error-value 966 TBD6: Attempted LSP Scheduling if the scheduling 967 capability was not advertised 969 11. Acknowledgments 971 The authors of this document would also like to thank Rafal Szarecki, 972 Adrian Farrel, Cyril Margaria for the review and comments. 974 12. References 976 12.1. Normative References 978 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 979 Requirement Levels", BCP 14, RFC 2119, 980 DOI 10.17487/RFC2119, March 1997, 981 . 983 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 984 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 985 DOI 10.17487/RFC5440, March 2009, 986 . 988 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 989 Writing an IANA Considerations Section in RFCs", BCP 26, 990 RFC 8126, DOI 10.17487/RFC8126, June 2017, 991 . 993 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 994 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 995 May 2017, . 997 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 998 Computation Element Communication Protocol (PCEP) 999 Extensions for Stateful PCE", RFC 8231, 1000 DOI 10.17487/RFC8231, September 2017, 1001 . 1003 [RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 1004 and D. Dhody, "Optimizations of Label Switched Path State 1005 Synchronization Procedures for a Stateful PCE", RFC 8232, 1006 DOI 10.17487/RFC8232, September 2017, 1007 . 1009 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 1010 Computation Element Communication Protocol (PCEP) 1011 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 1012 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 1013 . 1015 12.2. Informative References 1017 [I-D.ietf-detnet-architecture] 1018 Finn, N., Thubert, P., Varga, B., and J. Farkas, 1019 "Deterministic Networking Architecture", draft-ietf- 1020 detnet-architecture-13 (work in progress), May 2019. 1022 [I-D.ietf-pce-pcep-yang] 1023 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 1024 YANG Data Model for Path Computation Element 1025 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 1026 yang-13 (work in progress), October 2019. 1028 [I-D.litkowski-pce-state-sync] 1029 Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter 1030 Stateful Path Computation Element (PCE) Communication 1031 Procedures.", draft-litkowski-pce-state-sync-07 (work in 1032 progress), January 2020. 1034 [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP 1035 Authentication Option", RFC 5925, DOI 10.17487/RFC5925, 1036 June 2010, . 1038 [RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path 1039 Computation Element Architecture", RFC 7399, 1040 DOI 10.17487/RFC7399, October 2014, 1041 . 1043 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 1044 Code: The Implementation Status Section", BCP 205, 1045 RFC 7942, DOI 10.17487/RFC7942, July 2016, 1046 . 1048 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 1049 Stateful Path Computation Element (PCE)", RFC 8051, 1050 DOI 10.17487/RFC8051, January 2017, 1051 . 1053 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 1054 "PCEPS: Usage of TLS to Provide a Secure Transport for the 1055 Path Computation Element Communication Protocol (PCEP)", 1056 RFC 8253, DOI 10.17487/RFC8253, October 2017, 1057 . 1059 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1060 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1061 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1062 July 2018, . 1064 [RFC8413] Zhuang, Y., Wu, Q., Chen, H., and A. Farrel, "Framework 1065 for Scheduled Use of Resources", RFC 8413, 1066 DOI 10.17487/RFC8413, July 2018, 1067 . 1069 Appendix A. Contributors Addresses 1071 Dhruv Dhody 1072 Huawei 1073 Divyashree Techno Park, Whitefield 1074 Bangalore, Karnataka 560066 1075 India 1076 Email: dhruv.ietf@gmail.com 1078 Xufeng Liu 1079 Ericsson 1080 USA 1081 Email: xliu@kuatrotech.com 1083 Mehmet Toy 1084 Verizon 1085 USA 1086 Email: mehmet.toy@verizon.com 1088 Vic Liu 1089 China Mobile 1090 No.32 Xuanwumen West Street, Xicheng District 1091 Beijing, 100053 1092 China 1093 Email: liu.cmri@gmail.com 1095 Lei Liu 1096 Fujitsu 1097 USA 1098 Email: lliu@us.fujitsu.com 1100 Khuzema Pithewan 1101 Infinera 1102 Email: kpithewan@infinera.com 1104 Zitao Wang 1105 Huawei 1106 101 Software Avenue, Yuhua District 1107 Nanjing, Jiangsu 210012 1108 China 1110 Email: wangzitao@huawei.com 1112 Xian Zhang 1113 Huawei Technologies 1114 Research Area F3-1B, 1115 Huawei Industrial Base, 1116 Shenzhen, 518129, China 1118 Email: zhang.xian@huawei.com 1120 Authors' Addresses 1122 Huaimo Chen (editor) 1123 Futurewei 1124 Boston, MA 1125 USA 1127 Email: huaimo.chen@futurewei.com 1129 Yan Zhuang (editor) 1130 Huawei 1131 101 Software Avenue, Yuhua District 1132 Nanjing, Jiangsu 210012 1133 China 1135 Email: zhuangyan.zhuang@huawei.com 1137 Qin Wu 1138 Huawei 1139 101 Software Avenue, Yuhua District 1140 Nanjing, Jiangsu 210012 1141 China 1143 Email: bill.wu@huawei.com 1145 Daniele Ceccarelli 1146 Ericsson 1147 Via A. Negrone 1/A 1148 Genova - Sestri Ponente 1149 Italy 1151 Email: daniele.ceccarelli@ericsson.com