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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documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 7525 (Obsoleted by RFC 9325) == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-14 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group S. Litkowski 3 Internet-Draft Cisco Systems, Inc. 4 Intended status: Standards Track S. Sivabalan 5 Expires: April 2, 2021 Ciena 6 J. Tantsura 7 Apstra, Inc. 8 J. Hardwick 9 Metaswitch Networks 10 M. Negi 11 RtBrick India 12 C. Li 13 Huawei Technologies 14 September 29, 2020 16 Path Computation Element (PCE) communication Protocol (PCEP) extension 17 for associating Policies and Label Switched Paths (LSPs) 18 draft-ietf-pce-association-policy-12 20 Abstract 22 This document introduces a simple mechanism to associate policies to 23 a group of Label Switched Paths (LSPs) via an extension to the Path 24 Computation Element (PCE) Communication Protocol (PCEP). The 25 extension allows a PCEP speaker to advertise to a PCEP peer that a 26 particular LSP belongs to a particular Policy Association Group. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at https://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on April 2, 2021. 45 Copyright Notice 47 Copyright (c) 2020 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (https://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 63 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 64 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 3.1. Policy based Constraints . . . . . . . . . . . . . . . . 5 67 4. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 6 68 5. Policy Association Group . . . . . . . . . . . . . . . . . . 7 69 5.1. Policy Parameters TLV . . . . . . . . . . . . . . . . . . 7 70 6. Implementation Status . . . . . . . . . . . . . . . . . . . . 9 71 6.1. Cisco's Implementation . . . . . . . . . . . . . . . . . 9 72 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 73 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 74 8.1. Association object Type Indicators . . . . . . . . . . . 10 75 8.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 10 76 8.3. PCEP Errors . . . . . . . . . . . . . . . . . . . . . . . 10 77 9. Manageability Considerations . . . . . . . . . . . . . . . . 11 78 9.1. Control of Function and Policy . . . . . . . . . . . . . 11 79 9.2. Information and Data Models . . . . . . . . . . . . . . . 11 80 9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 11 81 9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 11 82 9.5. Requirements on Other Protocols . . . . . . . . . . . . . 11 83 9.6. Impact on Network Operations . . . . . . . . . . . . . . 11 84 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 85 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 86 11.1. Normative References . . . . . . . . . . . . . . . . . . 12 87 11.2. Informative References . . . . . . . . . . . . . . . . . 12 88 Appendix A. Example of Policy Parameters . . . . . . . . . . . . 15 89 Appendix B. Contributor Addresses . . . . . . . . . . . . . . . 15 90 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 92 1. Introduction 94 [RFC5440] describes the Path Computation Element communication 95 Protocol (PCEP) which enables the communication between a Path 96 Computation Client (PCC) and a Path Control Element (PCE), or between 97 two PCEs based on the PCE architecture [RFC4655]. [RFC5394] provides 98 additional details on policy within the PCE architecture and also 99 provides context for the support of PCE Policy. 101 PCEP Extensions for Stateful PCE Model [RFC8231] describes a set of 102 extensions to PCEP to enable active control of Multiprotocol Label 103 Switching Traffic Engineering (MPLS-TE) and Generalized MPLS (GMPLS) 104 tunnels. [RFC8281] describes the set-up and teardown of PCE- 105 initiated LSPs under the active stateful PCE model, without the need 106 for local configuration on the PCC, thus allowing for a dynamic 107 network. Currently, the LSPs can either be signaled via Resource 108 Reservation Protocol Traffic Engineering (RSVP-TE) or can be segment 109 routed as specified in [RFC8664]. 111 [RFC8697] introduces a generic mechanism to create a grouping of LSPs 112 which can then be used to define associations between a set of LSPs 113 and a set of attributes (such as configuration parameters or 114 behaviors) and is equally applicable to stateful PCE (active and 115 passive modes) and stateless PCE. 117 This document specifies a PCEP extension to associate one or more 118 LSPs with policies using the generic association mechanism. 120 A PCEP speaker may want to influence the PCEP peer with respect to 121 path selection and other policies. This document describes a PCEP 122 extension to associate policies by creating Policy Association Group 123 (PAG) and encoding this association in PCEP messages. The 124 specification is applicable to both stateful and stateless PCEP 125 sessions. 127 Note that the actual policy definition and the associated parameters 128 are out of scope of this document. 130 1.1. Requirements Language 132 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 133 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 134 "OPTIONAL" in this document are to be interpreted as described in BCP 135 14 [RFC2119] [RFC8174] when, and only when, they appear in all 136 capitals, as shown here. 138 2. Terminology 140 The following terminology is used in this document. 142 Association parameters: As described in [RFC8697], the combination 143 of the mandatory fields Association type, Association ID and 144 Association Source in the ASSOCIATION object uniquely identify the 145 association group. If the optional TLVs - Global Association 146 Source or Extended Association ID are included, then they are 147 included in combination with mandatory fields to uniquely identify 148 the association group. 150 Association information: As described in [RFC8697], the ASSOCIATION 151 object could include other optional TLVs based on the association 152 types, that provide 'information' related to the association. 154 LSR: Label Switch Router. 156 MPLS: Multiprotocol Label Switching. 158 PAG: Policy Association Group. 160 PAT: Policy Association Type. 162 PCC: Path Computation Client. Any client application requesting a 163 path computation to be performed by a Path Computation Element. 165 PCE: Path Computation Element. An entity (component, application, 166 or network node) that is capable of computing a network path or 167 route based on a network graph and applying computational 168 constraints. 170 PCEP: Path Computation Element Communication Protocol. 172 3. Motivation 174 Paths computed using PCE can be subjected to various policies at both 175 the PCE and the PCC. For example, in a centralized traffic 176 engineering (TE) scenario, network operators may instantiate LSPs and 177 specify policies for traffic accounting, path monitoring, telemetry, 178 etc., for some LSPs via the Stateful PCE. Similarly, a PCC could 179 request a user- or service-specific policy to be applied at the PCE, 180 such as constraints relaxation policy to meet optimal QoS and 181 resiliency. 183 PCEP speaker can use the generic mechanism as per [RFC8697] to 184 associate a set of LSPs with a policy, without the need to know the 185 details of such a policy, which simplifies network operations, avoids 186 frequent software upgrades, as well as provides an ability to 187 introduce new policies faster. 189 PAG Y 190 {Service-Specific Policy 191 for constraint 192 Monitor LSP relaxation} 193 | | 194 | PAG X PCReq/PCRpt | 195 V {Monitor LSP} {PAG Y} V 196 +-----+ ----------------> +-----+ 197 _ _ _ _ _ _| PCE | | | PCE | 198 | +-----+ | ----------> +-----+ 199 | PCInitiate/PCUpd | | PCReq/PCRpt 200 |{PAG X} | | {PAG Y} 201 | | | 202 | .-----. | | .-----. 203 | ( ) | +----+ ( ) 204 | .--( )--. | |PCC1|--.--( )--. 205 V ( ) | +----+ ( ) 206 +---+ ( ) | ( ) 207 |PCC|----( (G)MPLS network ) +----+ ( (G)MPLS network ) 208 +---+ ( ) |PCC2|------( ) 209 PAG X ( ) +----+ ( ) 210 {Monitor '--( )--' '--( )--' 211 LSP} ( ) ( ) 212 '-----' '-----' 214 Case 1: Policy requested by PCE Case 2: Policy requested by 215 and enforced by PCC PCC and enforced by 216 PCE 218 Figure 1: Sample use-cases for carrying policies over PCEP 220 3.1. Policy based Constraints 222 In the context of policy-enabled path computation [RFC5394], path 223 computation policies may be applied at both a PCC and a PCE. 224 Consider a Label Switch Router (LSR) with a policy enabled PCC, it 225 receives a service request via signaling, including over a Network- 226 Network Interface (NNI) or User-Network Interface (UNI) reference 227 point, or receives a configuration request over a management 228 interface to establish a service. The PCC may also apply user- or 229 service-specific policies to decide how the path selection process 230 should be constrained, that is, which constraints, diversities, 231 optimization criterion, and constraint relaxation strategies should 232 be applied in order for the service LSP(s) to have a likelihood to be 233 successfully established and provide necessary QoS and resilience 234 against network failures. The user- or service-specific policies 235 applied to PCC and are then passed to the PCE along with the Path 236 computation request, in the form of constraints [RFC5394]. 238 PCEP speaker can use the generic mechanism as per [RFC8697] to 239 associate a set of LSPs with policy and its resulting path 240 computation constraints. This would simplify the path computation 241 message exchanges in PCEP. 243 4. Overview 245 As per [RFC8697], LSPs are associated with other LSPs with which they 246 interact by adding them to a common association group. Grouping can 247 also be used to define the association between LSPs and policies 248 associated to them. As described in [RFC8697], the association group 249 is uniquely identified by the combination of the following fields in 250 the ASSOCIATION object: Association Type, Association ID, Association 251 Source, and (if present) Global Association Source or Extended 252 Association ID. This document defines a new Association type, called 253 "Policy Association" (TBD1), based on the generic ASSOCIATION object. 254 This new Association type is also called "PAT", for "Policy 255 Association Type". 257 [RFC8697] specifies the mechanism for the capability advertisement of 258 the Association types supported by a PCEP speaker by defining a 259 ASSOC-Type-List TLV to be carried within an OPEN object. This 260 capability exchange for the PAT (TBD1) MUST be done before using the 261 policy association. Thus the PCEP speaker MUST include the PAT 262 (TBD1) in the ASSOC-Type-List TLV and MUST receive the same from the 263 PCEP peer before using the Policy Association Group (PAG) in PCEP 264 messages. 266 This Association type is operator-configured [RFC8697] association in 267 nature and created by the operator manually on the PCEP peers. An 268 LSP belonging to this association is conveyed via PCEP messages to 269 the PCEP peer. Operator-configured Association Range MUST NOT be set 270 for this association-type, and MUST be ignored, so that the full 271 range of association identifier can be utilized. 273 A PAG can have one or more LSPs. The association parameters 274 including association identifier, Association type (PAT), as well as 275 the association source IP address is manually configured by the 276 operator and is used to identify the PAG as described in [RFC8697]. 277 The Global Association Source and Extended Association ID MAY also be 278 included. 280 As per the processing rules specified in section 6.4 of [RFC8697], if 281 a PCEP speaker does not support this Policy Association type, it 282 would return a PCErr message with Error-Type 26 "Association Error" 283 and Error-Value 1 "Association type is not supported". Since the PAG 284 is opaque in nature, the PAG and the policy MUST be configured on the 285 PCEP peers as per the operator-configured association procedures. 286 All further processing is as per section 6.4 of [RFC8697]. If a PCE 287 speaker receives PAG in a PCEP message, and the policy association 288 information is not configured, it MUST return a PCErr message with 289 Error-Type 26 "Association Error" and Error-Value 4 "Association 290 unknown". 292 Associating a particular LSP to multiple policy groups is authorized 293 from a protocol perspective, however, there is no assurance that the 294 PCEP speaker will be able to apply multiple policies. If a PCEP 295 speaker does not support handling of multiple policies for an LSP, it 296 MUST NOT add the LSP into the association group and MUST return a 297 PCErr with Error- Type 26 (Association Error) and Error-value 7 298 (Cannot join the association group). 300 5. Policy Association Group 302 Association groups and their memberships are defined using the 303 ASSOCIATION object defined in [RFC8697]. Two object types for IPv4 304 and IPv6 are defined. The ASSOCIATION object includes "Association 305 type" indicating the type of the association group. This document 306 add a new Association type (PAT). 308 PAG may carry optional TLVs including but not limited to - 310 o POLICY-PARAMETERS-TLV: Used to communicate opaque information 311 useful to apply the policy, described in Section 5.1. 313 o VENDOR-INFORMATION-TLV: Used to communicate arbitrary vendor 314 specific behavioral information, described in [RFC7470]. 316 5.1. Policy Parameters TLV 318 The POLICY-PARAMETERS-TLV is an optional TLV that can be carried in 319 ASSOCIATION object (for PAT) to carry opaque information needed to 320 apply the policy at the PCEP peer. In some cases to apply a PCE 321 policy successfully, it is required to also associate some policy 322 parameters that need to be evaluated. This TLV is used to carry 323 those policy parameters. The TLV could include one or more policy 324 related parameters. The encoding format and the order MUST be known 325 to the PCEP peers, this could be done during the configuration of the 326 policy (and its association parameters) for the PAG. The TLV format 327 is as per the format of the PCEP TLVs, as defined in [RFC5440], and 328 shown in Figure 2. Only one POLICY-PARAMETERS-TLV can be carried and 329 only the first occurrence is processed and any others MUST be 330 ignored. 332 0 1 2 3 333 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 1 334 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 335 | Type=TBD2 | Length | 336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 337 | | 338 // Policy Parameters // 339 | | 340 +---------------------------------------------------------------+ 342 Figure 2: The POLICY-PARAMETERS-TLV format 344 The type of the POLICY-PARAMETERS-TLV is TBD2 and it has a variable 345 length. The Value field is variable and padded to a 4-byte 346 alignment; padding is not included in the Length field. The PCEP 347 peer implementation needs to be aware of the encoding format, order, 348 and meaning of the 'Policy Parameters' well in advance based on the 349 policy. Note that from the protocol point of view this data is 350 opaque and can be used to carry parameters in any format understood 351 by the PCEP peers and associated to the policy. The exact use of 352 this TLV is beyond the scope of this document. Examples are included 353 for illustration purposes in Appendix A. 355 If the PCEP peer is unaware of the policy parameters associated with 356 the policy and it receives the POLICY-PARAMETERS-TLV, it MUST reject 357 the PCEP message and send a PCErr message with Error-Type 26 358 "Association Error" and Error-Value TBD3 "Not expecting policy 359 parameters". Further, if one or more parameters in the POLICY- 360 PARAMETERS-TLV received by the PCEP speaker are considered as 361 unacceptable in the context of the associated policy (e.g. out of 362 range value, badly encoded value...), the PCEP speaker MUST reject 363 the PCEP message and send a PCErr message with Error-Type 26 364 "Association Error" and Error-Value TBD4 "Unacceptable policy 365 parameters". 367 Note that, the vendor-specific behavioral information is encoded in 368 VENDOR-INFORMATION-TLV which can be used along with this TLV. 370 6. Implementation Status 372 [Note to the RFC Editor - remove this section before publication, as 373 well as remove the reference to RFC 7942.] 375 This section records the status of known implementations of the 376 protocol defined by this specification at the time of posting of this 377 Internet-Draft, and is based on a proposal described in [RFC7942]. 378 The description of implementations in this section is intended to 379 assist the IETF in its decision processes in progressing drafts to 380 RFCs. Please note that the listing of any individual implementation 381 here does not imply endorsement by the IETF. Furthermore, no effort 382 has been spent to verify the information presented here that was 383 supplied by IETF contributors. This is not intended as, and must not 384 be construed to be, a catalog of available implementations or their 385 features. Readers are advised to note that other implementations may 386 exist. 388 According to [RFC7942], "this will allow reviewers and working groups 389 to assign due consideration to documents that have the benefit of 390 running code, which may serve as evidence of valuable experimentation 391 and feedback that have made the implemented protocols more mature. 392 It is up to the individual working groups to use this information as 393 they see fit". 395 6.1. Cisco's Implementation 397 o Organization: Cisco Systems, Inc. 399 o Implementation: IOS-XR PCE and PCC. 401 o Description: The PCEP extension specified in this document is used 402 to convey traffic steering policies. 404 o Maturity Level: In shipping product. 406 o Coverage: Partial. 408 o Contact: mkoldych@cisco.com 410 7. Security Considerations 412 This document defines one new type for association, which do not add 413 any new security concerns beyond those discussed in [RFC5440], 414 [RFC8231] and [RFC8697] in itself. 416 Extra care needs to be taken by the implementation with respect to 417 POLICY-PARAMETERS-TLV while decoding, verifying, and applying these 418 policy variables. This TLV parsing could be exploited by an 419 attacker. 421 Some deployments may find policy associations and their implications 422 as extra sensitive and thus securing the PCEP session using Transport 423 Layer Security (TLS) [RFC8253], as per the recommendations and best 424 current practices in BCP 195 [RFC7525], is RECOMMENDED. 426 8. IANA Considerations 428 8.1. Association object Type Indicators 430 This document defines a new Association type. The sub-registry 431 "ASSOCIATION Type Field" of the "Path Computation Element Protocol 432 (PCEP) Numbers" registry was originally defined in [RFC8697]. IANA 433 is requested to confirm the early-allocated codepoint. 435 Value Name Reference 437 3 Policy Association [This.I-D] 439 8.2. PCEP TLV Type Indicators 441 The following TLV Type Indicator value is requested within the "PCEP 442 TLV Type Indicators" subregistry of the "Path Computation Element 443 Protocol (PCEP) Numbers" registry. IANA is requested to confirm the 444 early-allocated codepoint. 446 Value Description Reference 448 48 POLICY-PARAMETERS-TLV [This.I-D] 450 8.3. PCEP Errors 452 This document defines new Error-Values for Error-type 26 "Association 453 Error" defined in [RFC8697]. IANA is requested to allocate new error 454 values within the "PCEP- ERROR Object Error Types and Values" 455 subregistry of the PCEP Numbers registry as follows: 457 Error-Type Meaning Error-value Reference 459 26 Association [RFC8697] 460 Error 461 TBD3: Not expecting [This.I-D] 462 policy parameters 464 TBD4: Unacceptable [This.I-D] 465 policy parameters 467 9. Manageability Considerations 469 9.1. Control of Function and Policy 471 An operator MUST be allowed to configure the policy associations at 472 PCEP peers and associate it with the LSPs. They MAY also allow 473 configuration to related policy parameters, in which case the 474 operator MUST also be allowed to set the encoding format and order to 475 parse the associated policy parameters TLV. 477 9.2. Information and Data Models 479 [RFC7420] describes the PCEP MIB, there are no new MIB Objects for 480 this document. 482 The PCEP YANG module is defined in [I-D.ietf-pce-pcep-yang]. This 483 module supports associations as defined in [RFC8697] and thus 484 supports the Policy Association groups. 486 An implementation SHOULD allow the operator to view the PAG 487 configured. Further implementation SHOULD allow to view associations 488 reported by each peer, and the current set of LSPs in the PAG. 490 9.3. Liveness Detection and Monitoring 492 Mechanisms defined in this document do not imply any new liveness 493 detection and monitoring requirements in addition to those already 494 listed in [RFC5440], [RFC8231], and [RFC8281]. 496 9.4. Verify Correct Operations 498 Mechanisms defined in this document do not imply any new operation 499 verification requirements in addition to those already listed in 500 [RFC5440], [RFC8231], and [RFC8281]. 502 9.5. Requirements on Other Protocols 504 Mechanisms defined in this document do not imply any new requirements 505 on other protocols. 507 9.6. Impact on Network Operations 509 Mechanisms defined in this document do not have any impact on network 510 operations in addition to those already listed in [RFC5440], 511 [RFC8231], and [RFC8281]. 513 10. Acknowledgments 515 A special thanks to the authors of [RFC8697], this document borrowed 516 some of the text from it. The authors would like to thank Aijun 517 Wang, Peng Shuping, and Gyan Mishra for their useful comments. 519 11. References 521 11.1. Normative References 523 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 524 Requirement Levels", BCP 14, RFC 2119, 525 DOI 10.17487/RFC2119, March 1997, 526 . 528 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 529 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 530 DOI 10.17487/RFC5440, March 2009, 531 . 533 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 534 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 535 May 2017, . 537 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 538 Computation Element Communication Protocol (PCEP) 539 Extensions for Stateful PCE", RFC 8231, 540 DOI 10.17487/RFC8231, September 2017, 541 . 543 [RFC8697] Minei, I., Crabbe, E., Sivabalan, S., Ananthakrishnan, H., 544 Dhody, D., and Y. Tanaka, "Path Computation Element 545 Communication Protocol (PCEP) Extensions for Establishing 546 Relationships between Sets of Label Switched Paths 547 (LSPs)", RFC 8697, DOI 10.17487/RFC8697, January 2020, 548 . 550 11.2. Informative References 552 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 553 Element (PCE)-Based Architecture", RFC 4655, 554 DOI 10.17487/RFC4655, August 2006, 555 . 557 [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, 558 "Network Time Protocol Version 4: Protocol and Algorithms 559 Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, 560 . 562 [RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash, 563 "Policy-Enabled Path Computation Framework", RFC 5394, 564 DOI 10.17487/RFC5394, December 2008, 565 . 567 [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. 568 Hardwick, "Path Computation Element Communication Protocol 569 (PCEP) Management Information Base (MIB) Module", 570 RFC 7420, DOI 10.17487/RFC7420, December 2014, 571 . 573 [RFC7470] Zhang, F. and A. Farrel, "Conveying Vendor-Specific 574 Constraints in the Path Computation Element Communication 575 Protocol", RFC 7470, DOI 10.17487/RFC7470, March 2015, 576 . 578 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 579 "Recommendations for Secure Use of Transport Layer 580 Security (TLS) and Datagram Transport Layer Security 581 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 582 2015, . 584 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 585 Code: The Implementation Status Section", BCP 205, 586 RFC 7942, DOI 10.17487/RFC7942, July 2016, 587 . 589 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 590 "PCEPS: Usage of TLS to Provide a Secure Transport for the 591 Path Computation Element Communication Protocol (PCEP)", 592 RFC 8253, DOI 10.17487/RFC8253, October 2017, 593 . 595 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 596 Computation Element Communication Protocol (PCEP) 597 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 598 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 599 . 601 [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 602 and J. Hardwick, "Path Computation Element Communication 603 Protocol (PCEP) Extensions for Segment Routing", RFC 8664, 604 DOI 10.17487/RFC8664, December 2019, 605 . 607 [I-D.ietf-pce-pcep-yang] 608 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 609 YANG Data Model for Path Computation Element 610 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 611 yang-14 (work in progress), July 2020. 613 Appendix A. Example of Policy Parameters 615 An example could be a monitoring and telemetry policy P1 that is 616 dependent on a profile (GOLD/SILVER/BRONZE) as set by the operator. 617 The PCEP peers need to be aware of the policy P1 (and its associated 618 characteristics) in advance as well the fact that the policy 619 parameter will encode the profile of type string in the POLICY- 620 PARAMETERS-TLV. As an example, LSP1 could encode the PAG with the 621 POLICY-PARAMETERS-TLV with a string "GOLD". 623 Another example where the path computation at PCE could be dependent 624 on when the LSP was configured at the PCC. For such a policy P2, the 625 time-stamp can be encoded in the POLICY-PARAMETERS-TLV and the exact 626 encoding could be the 64-bit timestamp format as defined in 627 [RFC5905]. 629 While the above example has a single field in the POLICY-PARAMETERS- 630 TLV, it is possible to include multiple fields, but the exact order, 631 encoding format and meanings need to be known in advance at the PCEP 632 peers. 634 Appendix B. Contributor Addresses 635 Dhruv Dhody 636 Huawei Technologies 637 Divyashree Techno Park, Whitefield 638 Bangalore, Karnataka 560066 639 India 641 EMail: dhruv.ietf@gmail.com 643 Qin Wu 644 Huawei Technologies 645 101 Software Avenue, Yuhua District 646 Nanjing, Jiangsu 210012 647 China 649 EMail: sunseawq@huawei.com 651 Xian Zhang 652 Huawei Technologies 653 Bantian, Longgang District 654 Shenzhen 518129 655 P.R.China 657 EMail: zhang.xian@huawei.com 659 Udayasree Palle 661 EMail: udayasreereddy@gmail.com 663 Mike Koldychev 664 Cisco Systems, Inc. 665 Canada 667 EMail: mkoldych@cisco.com 669 Authors' Addresses 671 Stephane Litkowski 672 Cisco Systems, Inc. 673 11 Rue Camille Desmoulins 674 Issy-les-Moulineaux 92130 675 France 677 EMail: slitkows@cisco.com 678 Siva Sivabalan 679 Ciena 680 385 Terry Fox Drive 681 Kanata, Ontario K2K 0L1 682 Canada 684 EMail: msiva282@gmail.com 686 Jeff Tantsura 687 Apstra, Inc. 689 EMail: jefftant.ietf@gmail.com 691 Jonathan Hardwick 692 Metaswitch Networks 693 100 Church Street 694 Enfield, Middlesex 695 UK 697 EMail: Jonathan.Hardwick@metaswitch.com 699 Mahendra Singh Negi 700 RtBrick India 701 N-17L, Floor-1, 18th Cross Rd, HSR Layout Sector-3 702 Bangalore, Karnataka 560102 703 India 705 EMail: mahend.ietf@gmail.com 707 Cheng Li 708 Huawei Technologies 709 Huawei Campus, No. 156 Beiqing Rd. 710 Beijing 100095 711 China 713 EMail: c.l@huawei.com