idnits 2.17.1 draft-ietf-pce-lsp-control-request-10.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (October 13, 2019) is 1657 days in the past. Is this intentional? 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documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 7525 (Obsoleted by RFC 9325) == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-12 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--).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 A. Raghuram 3 Internet-Draft A. Goddard 4 Intended status: Standards Track AT&T 5 Expires: April 15, 2020 J. Karthik 6 S. Sivabalan 7 Cisco Systems, Inc. 8 M. Negi 9 Huawei Technologies 10 October 13, 2019 12 Ability for a Stateful Path Computation Element (PCE) to request and 13 obtain control of a Label Switched Path (LSP) 14 draft-ietf-pce-lsp-control-request-10 16 Abstract 18 A Stateful Path Computation Element (PCE) retains information about 19 the placement of Multiprotocol Label Switching (MPLS) Traffic 20 Engineering Label Switched Paths (TE LSPs). When a PCE has stateful 21 control over LSPs it may send indications to LSP head-ends to modify 22 the attributes (especially the paths) of the LSPs. A Path 23 Computation Client (PCC) that has set up LSPs under local 24 configuration may delegate control of those LSPs to a stateful PCE. 26 There are use-cases in which a stateful PCE may wish to obtain 27 control of locally configured LSPs of which it is aware but that have 28 not been delegated to the PCE. 30 This document describes an extension to the Path Computation Element 31 communication Protocol (PCEP) to enable a PCE to make requests for 32 such control. 34 Status of This Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at https://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on April 15, 2020. 50 Copyright Notice 52 Copyright (c) 2019 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (https://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 70 3. LSP Control Request Flag . . . . . . . . . . . . . . . . . . 4 71 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 72 5. Implementation Status . . . . . . . . . . . . . . . . . . . . 6 73 5.1. Huawei's Proof of Concept based on ONOS . . . . . . . . . 6 74 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 75 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 76 7.1. SRP Object Flags . . . . . . . . . . . . . . . . . . . . 7 77 8. Manageability Considerations . . . . . . . . . . . . . . . . 8 78 8.1. Control of Function and Policy . . . . . . . . . . . . . 8 79 8.2. Information and Data Models . . . . . . . . . . . . . . . 8 80 8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 8 81 8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 8 82 8.5. Requirements On Other Protocols . . . . . . . . . . . . . 8 83 8.6. Impact On Network Operations . . . . . . . . . . . . . . 8 84 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 85 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 86 10.1. Normative References . . . . . . . . . . . . . . . . . . 9 87 10.2. Informative References . . . . . . . . . . . . . . . . . 10 88 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 11 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 91 1. Introduction 93 Stateful Path Computation Element (PCE) communication Protocol (PCEP) 94 extensions [RFC8231] specifies a set of extensions to PCEP [RFC5440] 95 to enable stateful control of Traffic Engineering Label Switched 96 Paths (TE LSPs) between and across PCEP sessions in compliance with 97 [RFC4657]. It includes mechanisms to effect LSP state 98 synchronization between Path Computation Clients (PCCs) and PCEs, 99 delegation of control of LSPs to PCE, and PCE control of timing and 100 sequence of path computations within and across PCEP sessions. The 101 stateful PCEP defines the following two useful network operations: 103 o Delegation: As per [RFC8051], an operation to grant a PCE 104 temporary rights to modify a subset of LSP parameters on one or 105 more LSPs of a PCC. LSPs are delegated from a PCC to a PCE and 106 are referred to as "delegated" LSPs. 108 o Revocation: As per [RFC8231], an operation performed by a PCC on a 109 previously delegated LSP. Revocation revokes the rights granted 110 to the PCE in the delegation operation. 112 For Redundant Stateful PCEs (section 5.7.4. of [RFC8231]), during a 113 PCE failure, one of the redundant PCE could request to take control 114 over an LSP. The redundant PCEs may use a local policy or a 115 proprietary election mechanism to decide which PCE would take 116 control. In this case, a mechanism is needed for a stateful PCE to 117 request control of one or more LSPs from a PCC, so that a newly 118 elected primary PCE can request to take over control. 120 In case of virtualized PCEs (vPCE) running in virtual network 121 function (VNF) mode, as the computation load in the network 122 increases, a new instance of vPCE could be instantiated to balance 123 the current load. The PCEs could use a proprietary algorithm to 124 decide which LSPs to be assigned to the new vPCE. Thus, having a 125 mechanism for the PCE to request control of some LSPs is needed. 127 In some deployments, the operator would like to use stateful PCE for 128 global optimization algorithms but would still like to keep the 129 control of the LSP at the PCC. In such cases, a stateful PCE could 130 request to take control during the global optimization and return the 131 delegation once done. 133 Note that [RFC8231] specifies a mechanism for a PCC to delegate an 134 orphaned LSP to another PCE. The mechanism defined in this document 135 can be used in conjunction to [RFC8231]. Ultimately, it is the PCC 136 that decides which PCE to delegate the orphaned LSP to. 138 This specification provides a simple extension: by using it a PCE can 139 request control of one or more LSPs from any PCC over the stateful 140 PCEP session. The procedures for granting and relinquishing control 141 of the LSPs are specified in accordance with the specification 142 [RFC8231] unless explicitly set aside in this document. 144 2. Terminology 146 This document uses the following terms defined in [RFC5440]: 148 PCC: Path Computation Client. 150 PCE: Path Computation Element. 152 PCEP: Path Computation Element communication Protocol. 154 This document uses the following terms defined in [RFC8231]: 156 PCRpt: Path Computation State Report message. 158 PCUpd: Path Computation Update Request message. 160 PLSP-ID: A PCEP-specific identifier for the LSP. 162 SRP: Stateful PCE Request Parameters. 164 Readers of this document are expected to have some familiarity with 165 [RFC8231]. 167 2.1. Requirements Language 169 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 170 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 171 "OPTIONAL" in this document are to be interpreted as described in BCP 172 14 [RFC2119] [RFC8174] when, and only when, they appear in all 173 capitals, as shown here. 175 3. LSP Control Request Flag 177 The Stateful PCE Request Parameters (SRP) object is defined in 178 Section 7.2 of [RFC8231] and it includes a Flags field. 180 A new flag, the "LSP-Control Request Flag" (C) - TBD, is introduced 181 in the SRP object. On a PCUpd message, a PCE sets the C Flag to 1 to 182 indicate that it wishes to gain control of LSPs. The LSPs are 183 identified by the LSP object. A PLSP-ID of value other than 0 and 184 0xFFFFF is used to identify the LSP for which the PCE requests 185 control. The PLSP-ID value of 0 indicates that the PCE is requesting 186 control of all LSPs originating from the PCC that it wishes to 187 delegate. The C Flag has no meaning in other PCEP messages that 188 carry an SRP object and the flag MUST be set to 0 on transmission and 189 MUST be ignored on receipt. 191 4. Operation 193 During normal operation, a PCC that wishes to delegate the control of 194 an LSP sets the D Flag (delegate, Section 7.3 of [RFC8231]) to 1 in 195 all PCRpt messages pertaining to the LSP. The PCE confirms the 196 delegation by setting D Flag to 1 in all PCUpd messages pertaining to 197 the LSP. The PCC revokes the control of the LSP from the PCE by 198 setting D Flag to 0 in PCRpt messages pertaining to the LSP. If the 199 PCE wishes to relinquish the control of the LSP, it sets D Flag to 0 200 in all PCUpd messages pertaining to the LSP. 202 If a PCE wishes to gain control over an LSP, it sends a PCUpd message 203 with C Flag set to 1 in SRP object. The LSP for which the PCE 204 requests control is identified by the PLSP-ID. The PLSP-ID of 0 205 indicates that the PCE wants control over all LSPs originating from 206 the PCC. A PCC that receives a PCUpd message with C Flag set to 1 207 and PLSP-ID of 0 MUST NOT trigger the error condition for unknown 208 PLSP-ID in an LSP update request as per [RFC8231]. The D Flag and C 209 Flag are mutually exclusive in a PCUpd message. The PCE SHOULD NOT 210 send a control request for the LSP which is already delegated to the 211 PCE, i.e. if the D Flag is set in the PCUpd message, then the C Flag 212 SHOULD NOT be set. If a PCC receives a PCUpd message with D Flag set 213 in the LSP object (i.e. LSP is already delegated) and the C Flag is 214 also set (i.e. PCE is making a control request), the PCC MUST ignore 215 the C Flag. A PCC can decide to delegate the control of the LSP at 216 its own discretion. If the PCC grants or denies the control, it 217 sends a PCRpt message with D Flag set to 1 and 0 respectively in 218 accordance with stateful PCEP [RFC8231]. If the PCC does not grant 219 the control, it MAY choose to not respond, and the PCE MAY choose to 220 retry requesting the control preferably using exponentially 221 increasing timer. A PCE ignores the C Flag on the PCRpt message. 222 Note that, if the PCUpd message with C Flag set is received for a 223 currently non-delegated LSP (for which the PCE is requesting 224 delegation), this MUST NOT trigger the error handling as specified in 225 [RFC8231] (a PCErr with Error-type=19 (Invalid Operation) and error- 226 value 1 (Attempted LSP Update Request for a non-delegated LSP)). 228 As per [RFC8231], a PCC cannot delegate an LSP to more than one PCE 229 at any time. If a PCE requests control of an LSP that has already 230 been delegated by the PCC to another PCE, the PCC MAY ignore the 231 request, or MAY revoke the delegation to the first PCE before 232 delegating it to the second. This choice is a matter of local 233 policy. 235 It should be noted that a legacy implementation of PCC that does not 236 support this extension would trigger the error condition as specified 237 in [RFC8231] (a PCErr with Error-type=19 (Invalid Operation) and 238 error-value 1 (Attempted LSP Update Request for a non-delegated 239 LSP)), as the D Flag would be unset in this update request. Further, 240 in case of PLSP-ID of 0, the error condition as specified in 241 [RFC8231] (a PCErr with Error-type=19 (Invalid Operation) and error- 242 value 3 (Attempted LSP Update Request for an LSP identified by an 243 unknown PSP-ID)) would be triggered. 245 [RFC8281] describes the setup, maintenance and teardown of PCE- 246 initiated LSPs under the stateful PCE model. It also specifies how a 247 PCE may obtain control over an orphaned LSP that was PCE-initiated. 248 A PCE implementation can apply the mechanism described in this 249 document in conjunction with those in [RFC8281]. 251 5. Implementation Status 253 [Note to the RFC Editor - remove this section before publication, as 254 well as remove the reference to RFC 7942.] 256 This section records the status of known implementations of the 257 protocol defined by this specification at the time of posting of this 258 Internet-Draft, and is based on a proposal described in [RFC7942]. 259 The description of implementations in this section is intended to 260 assist the IETF in its decision processes in progressing drafts to 261 RFCs. Please note that the listing of any individual implementation 262 here does not imply endorsement by the IETF. Furthermore, no effort 263 has been spent to verify the information presented here that was 264 supplied by IETF contributors. This is not intended as, and must not 265 be construed to be, a catalog of available implementations or their 266 features. Readers are advised to note that other implementations may 267 exist. 269 According to [RFC7942], "this will allow reviewers and working groups 270 to assign due consideration to documents that have the benefit of 271 running code, which may serve as evidence of valuable experimentation 272 and feedback that have made the implemented protocols more mature. 273 It is up to the individual working groups to use this information as 274 they see fit". 276 5.1. Huawei's Proof of Concept based on ONOS 278 The PCE function was developed in the ONOS open source platform. 279 This extension was implemented on a private version as a proof of 280 concept to enable multi-instance support. 282 o Organization: Huawei 284 o Implementation: Huawei's PoC based on ONOS 285 o Description: PCEP as a southbound plugin was added to ONOS. To 286 support multi-instance ONOS deployment in a cluster, this 287 extension in PCEP is used. Refer 288 https://wiki.onosproject.org/display/ONOS/PCEP+Protocol 290 o Maturity Level: Prototype 292 o Coverage: Full 294 o Contact: satishk@huawei.com 296 6. Security Considerations 298 The security considerations listed in [RFC8231] and [RFC8281] apply 299 to this document as well. However, this document also introduces a 300 new attack vector. An attacker may flood the PCC with request to 301 delegate all of its LSPs at a rate which exceeds the PCC's ability to 302 process them, either by spoofing messages or by compromising the PCE 303 itself. The PCC SHOULD be configured with a threshold rate for the 304 delegation requests received from the PCE. If the threshold is 305 reached, it is RECOMMENDED to log the issue. 307 A PCC is the ultimate arbiter of delegation. As per [RFC8231], a 308 local policy at PCC is used to influence the delegation. A PCC can 309 also revoke the delegation at any time. A PCC MUST NOT blindly trust 310 the control requests and SHOULD take local policy and other factors 311 into consideration before honoring the request. 313 As per [RFC8231], it is RECOMMENDED that these PCEP extensions only 314 be activated on authenticated and encrypted sessions across PCEs and 315 PCCs belonging to the same administrative authority, using Transport 316 Layer Security (TLS) [RFC8253], as per the recommendations and best 317 current practices in [RFC7525] (unless explicitly excluded in 318 [RFC8253]). 320 7. IANA Considerations 322 7.1. SRP Object Flags 324 IANA maintains a registry called the "Path Computation Element 325 Protocol (PCEP) Numbers" registry. It contains a subregistry called 326 the "SRP Object Flag Field" registry. This document requests IANA to 327 allocate following code point in the "SRP Object Flag Field" 328 subregistry. 330 Bit Description Reference 331 TBD LSP-Control Request Flag This document 333 8. Manageability Considerations 335 All manageability requirements and considerations listed in [RFC5440] 336 and [RFC8231] apply to PCEP protocol extensions defined in this 337 document. In addition, requirements and considerations listed in 338 this section apply. 340 8.1. Control of Function and Policy 342 A PCC implementation SHOULD allow the operator to configure the 343 policy based on which it honors the request to control the LSPs. 344 This includes the handling of the case where an LSP control request 345 is received for an LSP that is currently delegated to some other PCE. 346 A PCC implementation SHOULD also allow the operator to configure the 347 threshold rate based on which it accepts the delegation requests from 348 the PCE. Further, the operator MAY be allowed to trigger the LSP 349 control request for a particular LSP at the PCE. A PCE 350 implementation SHOULD also allow the operator to configure an 351 exponentially increasing timer to retry the control requests for 352 which the PCE did not get a response. 354 8.2. Information and Data Models 356 The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to 357 include mechanism to trigger the LSP control request. 359 8.3. Liveness Detection and Monitoring 361 Mechanisms defined in this document do not imply any new liveness 362 detection and monitoring requirements in addition to those already 363 listed in [RFC5440]. 365 8.4. Verify Correct Operations 367 Mechanisms defined in this document do not imply any new operation 368 verification requirements in addition to those already listed in 369 [RFC5440] and [RFC8231]. 371 8.5. Requirements On Other Protocols 373 Mechanisms defined in this document do not imply any new requirements 374 on other protocols. 376 8.6. Impact On Network Operations 378 Mechanisms defined in [RFC5440] and [RFC8231] also apply to PCEP 379 extensions defined in this document. Further, the mechanism 380 described in this document can help the operator to request control 381 of the LSPs at a particular PCE. 383 9. Acknowledgements 385 Thanks to Jonathan Hardwick to remind the authors to not use 386 suggested values in IANA section. 388 Thanks to Adrian Farrel, Haomian Zheng and Tomonori Takeda for their 389 valuable comments. 391 Thanks to Shawn M. Emery for security directorate's review. 393 Thanks to Francesca Palombini for GENART review. 395 Thanks to Martin Vigoureux, Alvaro Retana, and Barry Leiba for IESG 396 reviews. 398 10. References 400 10.1. Normative References 402 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 403 Requirement Levels", BCP 14, RFC 2119, 404 DOI 10.17487/RFC2119, March 1997, 405 . 407 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 408 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 409 DOI 10.17487/RFC5440, March 2009, 410 . 412 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 413 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 414 May 2017, . 416 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 417 Computation Element Communication Protocol (PCEP) 418 Extensions for Stateful PCE", RFC 8231, 419 DOI 10.17487/RFC8231, September 2017, 420 . 422 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 423 Computation Element Communication Protocol (PCEP) 424 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 425 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 426 . 428 10.2. Informative References 430 [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 431 Element (PCE) Communication Protocol Generic 432 Requirements", RFC 4657, DOI 10.17487/RFC4657, September 433 2006, . 435 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 436 "Recommendations for Secure Use of Transport Layer 437 Security (TLS) and Datagram Transport Layer Security 438 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 439 2015, . 441 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 442 Code: The Implementation Status Section", BCP 205, 443 RFC 7942, DOI 10.17487/RFC7942, July 2016, 444 . 446 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 447 Stateful Path Computation Element (PCE)", RFC 8051, 448 DOI 10.17487/RFC8051, January 2017, 449 . 451 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 452 "PCEPS: Usage of TLS to Provide a Secure Transport for the 453 Path Computation Element Communication Protocol (PCEP)", 454 RFC 8253, DOI 10.17487/RFC8253, October 2017, 455 . 457 [I-D.ietf-pce-pcep-yang] 458 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 459 YANG Data Model for Path Computation Element 460 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 461 yang-12 (work in progress), July 2019. 463 Appendix A. Contributor Addresses 465 Dhruv Dhody 466 Huawei Technologies 467 Divyashree Techno Park, Whitefield 468 Bangalore, Karnataka 560066 469 India 471 EMail: dhruv.ietf@gmail.com 473 Jon Parker 474 Cisco Systems, Inc. 475 2000 Innovation Drive 476 Kanata, Ontario K2K 3E8 477 Canada 479 EMail: jdparker@cisco.com 481 Chaitanya Yadlapalli 482 AT&T 483 200 S Laurel Aevenue 484 Middletown NJ 07748 485 USA 487 EMail: cy098d@att.com 489 Authors' Addresses 491 Aswatnarayan Raghuram 492 AT&T 493 200 S Laurel Aevenue 494 Middletown, NJ 07748 495 USA 497 EMail: ar2521@att.com 499 Al Goddard 500 AT&T 501 200 S Laurel Aevenue 502 Middletown, NJ 07748 503 USA 505 EMail: ag6941@att.com 506 Jay Karthik 507 Cisco Systems, Inc. 508 125 High Street 509 Boston, Massachusetts 02110 510 USA 512 EMail: jakarthi@cisco.com 514 Siva Sivabalan 515 Cisco Systems, Inc. 516 2000 Innovation Drive 517 Kanata, Ontario K2K 3E8 518 Canada 520 EMail: msiva@cisco.com 522 Mahendra Singh Negi 523 Huawei Technologies 524 Divyashree Techno Park, Whitefield 525 Bangalore, Karnataka 560066 526 India 528 EMail: mahend.ietf@gmail.com