idnits 2.17.1 draft-ietf-pce-lsp-control-request-08.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 (August 24, 2019) is 1700 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documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 7525 (Obsoleted by RFC 9325) == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-12 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--).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: February 25, 2020 J. Karthik 6 S. Sivabalan 7 Cisco Systems, Inc. 8 M. Negi 9 Huawei Technologies 10 August 24, 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-08 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) has set up LSPs under local configuration 24 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 such requests. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at https://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on February 25, 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 . . . . . . . . . . . . . . . . . . . . . . . . . . 4 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 . . . . . . . . . . . . . . . . 7 78 8.1. Control of Function and Policy . . . . . . . . . . . . . 7 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 . . . . . . . . . . . . . . . . . . . . . . 8 85 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 86 10.1. Normative References . . . . . . . . . . . . . . . . . . 9 87 10.2. Informative References . . . . . . . . . . . . . . . . . 9 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 as virtual network 121 function (VNF), as the computation load in the network increases, a 122 new instance of vPCE could be instantiated to balance the current 123 load. The PCEs could use proprietary algorithm to decide which LSPs 124 to be assigned to the new vPCE. Thus having a mechanism for the PCE 125 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. 138 This specification provides a simple extension, by using this a PCE 139 can request control of one or more LSPs from any PCC over the 140 stateful PCEP session. The procedures for granting and relinquishing 141 control of the LSPs are specified in accordance with the 142 specification [RFC8231]. 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 2.1. Requirements Language 164 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 165 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 166 "OPTIONAL" in this document are to be interpreted as described in BCP 167 14 [RFC2119] [RFC8174] when, and only when, they appear in all 168 capitals, as shown here. 170 3. LSP Control Request Flag 172 The Stateful PCE Request Parameters (SRP) object is defined in 173 [RFC8231], it includes a Flags field. 175 A new flag, the "LSP-Control Request Flag" (C), is introduced in the 176 SRP object. On a PCUpd message, a PCE sets the C Flag to 1 to 177 indicate that, it wishes to gain control of LSPs. The LSPs are 178 identified by the LSP object. A PLSP-ID of value other than 0 and 179 0xFFFFF is used to identify the LSP for which the PCE requests 180 control. The PLSP-ID value of 0 indicates that the PCE is requesting 181 control of all LSPs originating from the PCC that it wishes to 182 delegate. The C Flag has no meaning in the PCRpt and PCInitiate 183 message and MUST be set to 0 on transmission and MUST be ignored on 184 receipt. 186 4. Operation 188 During normal operation, a PCC that wishes to delegate the control of 189 an LSP sets the D Flag (delegate) to 1 in all PCRpt messages 190 pertaining to the LSP. The PCE confirms the delegation by setting D 191 Flag to 1 in all PCUpd messages pertaining to the LSP. The PCC 192 revokes the control of the LSP from the PCE by setting D Flag to 0 in 193 PCRpt messages pertaining to the LSP. If the PCE wishes to 194 relinquish the control of the LSP, it sets D Flag to 0 in all PCUpd 195 messages pertaining to the LSP. 197 If a PCE wishes to gain control over an LSP, it sends a PCUpd message 198 with C Flag set to 1 in SRP object. The LSP for which the PCE 199 requests control is identified by the PLSP-ID. The PLSP-ID of 0 200 indicates that the PCE wants control over all LSPs originating from 201 the PCC. A PCC that receives a PCUpd message with C Flag set to 1 202 and PLSP-ID of 0 MUST NOT trigger the error condition for unknown 203 PLSP-ID in an LSP update request as per [RFC8231]. The D Flag and C 204 Flag are mutually exclusive in PCUpd message. The PCE SHOULD NOT 205 send control request for LSP which is already delegated to the PCE, 206 i.e. if the D Flag is set in the PCUpd message, then C Flag SHOULD 207 NOT be set. If a PCC receives a PCUpd message with D Flag set in the 208 LSP object (i.e. LSP is already delegated) and the C Flag is also 209 set (i.e. PCE is making a control request), the PCC MUST ignore the 210 C Flag. A PCC can decide to delegate the control of the LSP at its 211 own discretion. If the PCC grants or denies the control, it sends a 212 PCRpt message with D Flag set to 1 and 0 respectively in accordance 213 with stateful PCEP [RFC8231]. If the PCC does not grant the control, 214 it MAY choose to not respond, and the PCE MAY choose to retry 215 requesting the control preferably using exponentially increasing 216 timer. A PCE ignores the C Flag on the PCRpt message. Note that, 217 the PCUpd message with C Flag set is received for a currently non- 218 delegated LSP (for which the PCE is requesting delegation), this MUST 219 NOT trigger the error handling as specified in [RFC8231] (a PCErr 220 with Error-type=19 (Invalid Operation) and error-value 1 (Attempted 221 LSP Update Request for a non-delegated LSP)). 223 As per [RFC8231], a PCC cannot delegate an LSP to more than one PCE 224 at any time. If a PCE requests control of an LSP that has already 225 been delegated by the PCC to another PCE, the PCC MAY ignore the 226 request, or MAY revoke the delegation to the first PCE before 227 delegating it to the second. This choice is a matter of local 228 policy. 230 It should be noted that a legacy implementation of PCC, that does not 231 support this extension would trigger the error condition as specified 232 in [RFC8231] (a PCErr with Error-type=19 (Invalid Operation) and 233 error-value 1 (Attempted LSP Update Request for a non-delegated LSP)) 234 as the D Flag would be unset in this update request. Further, in 235 case of PLSP-ID of 0, the error condition as specified in [RFC8231] 236 (a PCErr with Error-type=19 (Invalid Operation) and error-value 3 237 (Attempted LSP Update Request for an LSP identified by an unknown 238 PSP-ID)) would be triggered. 240 [RFC8281] describes the setup, maintenance and teardown of PCE- 241 initiated LSPs under the stateful PCE model. It also specifies how a 242 PCE MAY obtain control over an orphaned LSP that was PCE-initiated. 243 A PCE implementation can apply the mechanism described in this 244 document in conjunction with those in [RFC8281]. 246 5. Implementation Status 248 [Note to the RFC Editor - remove this section before publication, as 249 well as remove the reference to RFC 7942.] 251 This section records the status of known implementations of the 252 protocol defined by this specification at the time of posting of this 253 Internet-Draft, and is based on a proposal described in [RFC7942]. 254 The description of implementations in this section is intended to 255 assist the IETF in its decision processes in progressing drafts to 256 RFCs. Please note that the listing of any individual implementation 257 here does not imply endorsement by the IETF. Furthermore, no effort 258 has been spent to verify the information presented here that was 259 supplied by IETF contributors. This is not intended as, and must not 260 be construed to be, a catalog of available implementations or their 261 features. Readers are advised to note that other implementations may 262 exist. 264 According to [RFC7942], "this will allow reviewers and working groups 265 to assign due consideration to documents that have the benefit of 266 running code, which may serve as evidence of valuable experimentation 267 and feedback that have made the implemented protocols more mature. 268 It is up to the individual working groups to use this information as 269 they see fit". 271 5.1. Huawei's Proof of Concept based on ONOS 273 The PCE function was developed in the ONOS open source platform. 274 This extension was implemented on a private version as a proof of 275 concept to enable multi-instance support. 277 o Organization: Huawei 279 o Implementation: Huawei's PoC based on ONOS 281 o Description: PCEP as a southbound plugin was added to ONOS. To 282 support multi-instance ONOS deployment in a cluster, this 283 extension in PCEP is used. Refer 284 https://wiki.onosproject.org/display/ONOS/PCEP+Protocol 286 o Maturity Level: Prototype 287 o Coverage: Full 289 o Contact: satishk@huawei.com 291 6. Security Considerations 293 The security considerations listed in [RFC8231] and [RFC8281] apply 294 to this document as well. However, this document also introduces a 295 new attack vector. An attacker may flood the PCC with request to 296 delegate all of its LSPs at a rate which exceeds the PCC's ability to 297 process them, either by spoofing messages or by compromising the PCE 298 itself. The PCC SHOULD be configured with a threshold rate for the 299 delegation requests received from the PCE. If the threshold is 300 reached, it is RECOMMENDED to log the issue. 302 As per [RFC8231], it is RECOMMENDED that these PCEP extensions only 303 be activated on authenticated and encrypted sessions across PCEs and 304 PCCs belonging to the same administrative authority, using Transport 305 Layer Security (TLS) [RFC8253], as per the recommendations and best 306 current practices in [RFC7525] (unless explicitly excluded in 307 [RFC8253]). 309 7. IANA Considerations 311 7.1. SRP Object Flags 313 IANA maintains a registry called the "Path Computation Element 314 Protocol (PCEP) Numbers" registry. It contains a subregistry called 315 the "SRP Object Flag Field" registry. This document requests IANA to 316 allocate following code point in the "SRP Object Flag Field" 317 subregistry. 319 Bit Description Reference 320 TBD LSP-Control This document 322 8. Manageability Considerations 324 All manageability requirements and considerations listed in [RFC5440] 325 and [RFC8231] apply to PCEP protocol extensions defined in this 326 document. In addition, requirements and considerations listed in 327 this section apply. 329 8.1. Control of Function and Policy 331 A PCC implementation SHOULD allow the operator to configure the 332 policy based on which it honors the request to control the LSPs. 333 This includes the handling of the case where an LSP control request 334 is received for an LSP that is currently delegated to some other PCE. 336 A PCC implementation SHOULD also allow the operator to configure the 337 threshold rate based on which it accepts the delegation requests from 338 the PCE. Further, the operator MAY be allowed to trigger the LSP 339 control request for a particular LSP at the PCE. A PCE 340 implementation SHOULD also allow the operator to configure an 341 exponentially increasing timer to retry the control requests for 342 which the PCE did not get a response. 344 8.2. Information and Data Models 346 The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to 347 include mechanism to trigger the LSP control request. 349 8.3. Liveness Detection and Monitoring 351 Mechanisms defined in this document do not imply any new liveness 352 detection and monitoring requirements in addition to those already 353 listed in [RFC5440]. 355 8.4. Verify Correct Operations 357 Mechanisms defined in this document do not imply any new operation 358 verification requirements in addition to those already listed in 359 [RFC5440] and [RFC8231]. 361 8.5. Requirements On Other Protocols 363 Mechanisms defined in this document do not imply any new requirements 364 on other protocols. 366 8.6. Impact On Network Operations 368 Mechanisms defined in [RFC5440] and [RFC8231] also apply to PCEP 369 extensions defined in this document. Further, the mechanism 370 described in this document can help the operator to request control 371 of the LSPs at a particular PCE. 373 9. Acknowledgements 375 Thanks to Jonathan Hardwick to remind the authors to not use 376 suggested values in IANA section. 378 Thanks to Adrian Farrel, Haomian Zheng and Tomonori Takeda for their 379 valuable comments. 381 Thanks to Shawn M. Emery for security directorate's review. 383 10. References 385 10.1. Normative References 387 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 388 Requirement Levels", BCP 14, RFC 2119, 389 DOI 10.17487/RFC2119, March 1997, 390 . 392 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 393 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 394 DOI 10.17487/RFC5440, March 2009, 395 . 397 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 398 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 399 May 2017, . 401 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 402 Computation Element Communication Protocol (PCEP) 403 Extensions for Stateful PCE", RFC 8231, 404 DOI 10.17487/RFC8231, September 2017, 405 . 407 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 408 Computation Element Communication Protocol (PCEP) 409 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 410 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 411 . 413 10.2. Informative References 415 [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 416 Element (PCE) Communication Protocol Generic 417 Requirements", RFC 4657, DOI 10.17487/RFC4657, September 418 2006, . 420 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 421 "Recommendations for Secure Use of Transport Layer 422 Security (TLS) and Datagram Transport Layer Security 423 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 424 2015, . 426 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 427 Code: The Implementation Status Section", BCP 205, 428 RFC 7942, DOI 10.17487/RFC7942, July 2016, 429 . 431 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 432 Stateful Path Computation Element (PCE)", RFC 8051, 433 DOI 10.17487/RFC8051, January 2017, 434 . 436 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 437 "PCEPS: Usage of TLS to Provide a Secure Transport for the 438 Path Computation Element Communication Protocol (PCEP)", 439 RFC 8253, DOI 10.17487/RFC8253, October 2017, 440 . 442 [I-D.ietf-pce-pcep-yang] 443 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 444 YANG Data Model for Path Computation Element 445 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 446 yang-12 (work in progress), July 2019. 448 Appendix A. Contributor Addresses 450 Dhruv Dhody 451 Huawei Technologies 452 Divyashree Techno Park, Whitefield 453 Bangalore, Karnataka 560066 454 India 456 EMail: dhruv.ietf@gmail.com 458 Jon Parker 459 Cisco Systems, Inc. 460 2000 Innovation Drive 461 Kanata, Ontario K2K 3E8 462 Canada 464 EMail: jdparker@cisco.com 466 Chaitanya Yadlapalli 467 AT&T 468 200 S Laurel Aevenue 469 Middletown NJ 07748 470 USA 472 EMail: cy098d@att.com 474 Authors' Addresses 476 Aswatnarayan Raghuram 477 AT&T 478 200 S Laurel Aevenue 479 Middletown, NJ 07748 480 USA 482 EMail: ar2521@att.com 484 Al Goddard 485 AT&T 486 200 S Laurel Aevenue 487 Middletown, NJ 07748 488 USA 490 EMail: ag6941@att.com 491 Jay Karthik 492 Cisco Systems, Inc. 493 125 High Street 494 Boston, Massachusetts 02110 495 USA 497 EMail: jakarthi@cisco.com 499 Siva Sivabalan 500 Cisco Systems, Inc. 501 2000 Innovation Drive 502 Kanata, Ontario K2K 3E8 503 Canada 505 EMail: msiva@cisco.com 507 Mahendra Singh Negi 508 Huawei Technologies 509 Divyashree Techno Park, Whitefield 510 Bangalore, Karnataka 560066 511 India 513 EMail: mahend.ietf@gmail.com