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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-11) exists of draft-ietf-pce-pce-initiated-lsp-10 == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-05 == Outdated reference: A later version (-18) exists of draft-ietf-pce-pceps-14 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). 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 C. Yadlapalli 5 Expires: January 17, 2018 AT&T 6 J. Karthik 7 S. Sivabalan 8 J. Parker 9 Cisco Systems, Inc. 10 D. Dhody 11 Huawei Technologies 12 July 16, 2017 14 Ability for a stateful PCE to request and obtain control of a LSP 15 draft-raghu-pce-lsp-control-request-04 17 Abstract 19 The stateful Path Computation Element (PCE) communication Protocol 20 (PCEP) extensions provide stateful control of Multiprotocol Label 21 Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSP) 22 via PCEP, for a model where a Path Computation Client (PCC) delegates 23 control over one or more locally configured LSPs to a stateful PCE. 24 There are use-cases in which a stateful PCE may wish to request and 25 obtain control of one or more LSPs from a PCC. This document 26 describes a simple extension to stateful PCEP to achieve such an 27 objective. 29 Requirements Language 31 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 32 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 33 document are to be interpreted as described in [RFC2119]. 35 Status of This Memo 37 This Internet-Draft is submitted in full conformance with the 38 provisions of BCP 78 and BCP 79. 40 Internet-Drafts are working documents of the Internet Engineering 41 Task Force (IETF). Note that other groups may also distribute 42 working documents as Internet-Drafts. The list of current Internet- 43 Drafts is at http://datatracker.ietf.org/drafts/current/. 45 Internet-Drafts are draft documents valid for a maximum of six months 46 and may be updated, replaced, or obsoleted by other documents at any 47 time. It is inappropriate to use Internet-Drafts as reference 48 material or to cite them other than as "work in progress." 49 This Internet-Draft will expire on January 17, 2018. 51 Copyright Notice 53 Copyright (c) 2017 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (http://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 69 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 70 3. LSP Control Request Flag . . . . . . . . . . . . . . . . . . 4 71 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 72 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 73 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 74 6.1. SRP Object Flags . . . . . . . . . . . . . . . . . . . . 5 75 7. Manageability Considerations . . . . . . . . . . . . . . . . 6 76 7.1. Control of Function and Policy . . . . . . . . . . . . . 6 77 7.2. Information and Data Models . . . . . . . . . . . . . . . 6 78 7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 6 79 7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 6 80 7.5. Requirements On Other Protocols . . . . . . . . . . . . . 6 81 7.6. Impact On Network Operations . . . . . . . . . . . . . . 6 82 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 83 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 84 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 85 9.2. Informative References . . . . . . . . . . . . . . . . . 7 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 88 1. Introduction 90 Stateful PCEP extensions [I-D.ietf-pce-stateful-pce] specifies a set 91 of extensions to PCEP [RFC5440] to enable stateful control of TE LSPs 92 between and across PCEP sessions in compliance with [RFC4657]. It 93 includes mechanisms to effect LSP state synchronization between PCCs 94 and PCEs, delegation of control of LSPs to PCEs, and PCE control of 95 timing and sequence of path computations within and across PCEP 96 sessions. The stateful PCEP defines the following two useful network 97 operations: 99 o Delegation: As per [RFC8051], an operation to grant a PCE 100 temporary rights to modify a subset of LSP parameters on one or 101 more LSPs of a PCC. LSPs are delegated from a PCC to a PCE and 102 are referred to as "delegated" LSPs. 104 o Revocation: As per [I-D.ietf-pce-stateful-pce], an operation 105 performed by a PCC on a previously delegated LSP. Revocation 106 revokes the rights granted to the PCE in the delegation operation. 108 For Redundant Stateful PCEs (section 5.7.4. of 109 [I-D.ietf-pce-stateful-pce]), during a PCE failure, one of the 110 redundant PCE could request to take control over an LSP. The 111 redundant PCEs MAY use a local policy or a proprietary election 112 mechanism to decide which PCE would take control. In this case, a 113 mechanism is needed for a stateful PCE to request control of one or 114 more LSPs from a PCC, so that a newly elected primary PCE can request 115 to take over control. 117 In case of virtualized PCEs (vPCE) running as virtual network 118 function (VNF), as the computation load in the network increases, a 119 new instance of vPCE could be instantiated to balance the current 120 load. The PCEs could use proprietary algorithm to decide which LSPs 121 to be assigned to the new vPCE. Thus having a mechanism for the PCE 122 to request control of some LSPs is needed. 124 In some deployments, the operator would like to use stateful PCE for 125 global optimization algorithms but would still like to keep the 126 control of the LSP at the PCC. In such cases, a stateful PCE could 127 request to take control during the global optimization and return the 128 delegation once done. 130 This specification provides a simple extension, by using this a PCE 131 can request control of one or more LSPs from any PCC over the 132 stateful PCEP channel. The procedures for granting and relinquishing 133 control of the LSPs are specified in accordance with the 134 specification [I-D.ietf-pce-stateful-pce]. 136 2. Terminology 138 The following terminologies are used in this document: 140 PCC: Path Computation Client. 142 PCE: Path Computation Element 143 PCEP: Path Computation Element communication Protocol. 145 PCRpt: Path Computation State Report message. 147 PCUpd: Path Computation Update Request message. 149 PLSP-ID: A PCEP-specific identifier for the LSP. 151 3. LSP Control Request Flag 153 The Stateful PCE Request Parameters (SRP) object is defined in 154 [I-D.ietf-pce-stateful-pce], it includes a Flags field. 155 [I-D.ietf-pce-pce-initiated-lsp] defines a R (LSP-REMOVE) flag. 157 A new flag, the "LSP Control Request Flag" (C), is introduced in the 158 SRP object. On a PCUpd message, a PCE sets the C Flag to 1 to 159 indicate that, it wishes to gain control of LSP(s). The LSP is 160 identified by the LSP object. A PLSP-ID of value other than 0 and 161 0xFFFFF is used to identify the LSP for which the PCE requests 162 control. The PLSP-ID value of 0 indicates that the PCE is requesting 163 control of all LSPs originating from the PCC that it wishes to 164 delegate. The flag has no meaning in the PCRpt and PCInitiate 165 message and SHOULD be set to 0 on transmission and MUST be ignored on 166 receipt. 168 4. Operation 170 During normal operation, a PCC that wishes to delegate the control of 171 an LSP sets the D Flag to 1 in all PCRpt messages pertaining to the 172 LSP. The PCE confirms the delegation by setting D Flag to 1 in all 173 PCUpd messages pertaining to the LSP. The PCC revokes the control of 174 the LSP from the PCE by setting D Flag to 0 in PCRpt messages 175 pertaining to the LSP. If the PCE wishes to relinquish the control 176 of the LSP, it sets D Flag to 0 in all PCUpd messages pertaining to 177 the LSP. 179 If a PCE wishes to gain control over an LSP, it sends a PCUpd message 180 with C Flag set to 1 in SRP object. The LSP for which the PCE 181 requests control is identified by the PLSP-ID. The PLSP-ID of 0 182 indicates that the PCE wants control over all LSPs originating from 183 the PCC. If the LSP(s) is/are already delegated to the PCE making 184 the request, the PCC ignores the C Flag. A PCC can decide to 185 delegate the control of the LSP at its own discretion. If the PCC 186 grants or denies the control, it sends PCRpt message with D Flag set 187 to 1 and 0 respectively in accordance with according with stateful 188 PCEP [I-D.ietf-pce-stateful-pce] . If the PCC does not grant the 189 control, it MAY choose to not respond, and the PCE may choose to 190 retry requesting the control preferably using exponentially 191 increasing timer. A PCE ignores the C Flag on the PCRpt message. 193 In case multiple PCEs request control over an LSP, and if the PCC is 194 willing to grant the control, the LSP MUST be delegated to only one 195 PCE chosen by the PCC based on its local policy. 197 It should be noted that a legacy implementation of PCC, that does not 198 understand the C flag in PCUpd message, would simply ignore the flag 199 and the request to grant control over the LSP. 201 [I-D.ietf-pce-pce-initiated-lsp] describes the setup, maintenance and 202 teardown of PCE-initiated LSPs under the stateful PCE model. It also 203 specify how a PCE MAY obtain control over an orphaned LSP that was 204 PCE-initiated. A PCE implementation can apply the mechanism 205 described in this document in conjunction with those in 206 [I-D.ietf-pce-pce-initiated-lsp]. 208 5. Security Considerations 210 The security considerations listed in [I-D.ietf-pce-stateful-pce] 211 apply to this document as well. However, this document also 212 introduces a new attack vectors. An attacker may flood the PCC with 213 request to delegate all its LSPs at a rate which exceeds the PCC's 214 ability to process them, either by spoofing messages or by 215 compromising the PCE itself. The PCC can simply ignore these 216 messages with no extra actions. Securing the PCEP session using 217 mechanism like Transport Layer Security (TLS) [I-D.ietf-pce-pceps] is 218 RECOMMENDED. 220 6. IANA Considerations 222 This document requests IANA actions to allocate code points for the 223 protocol elements defined in this document. 225 6.1. SRP Object Flags 227 The SRP object is defined in [I-D.ietf-pce-stateful-pce] and the 228 registry to manage the Flag field of the SRP object is requested in 229 [I-D.ietf-pce-pce-initiated-lsp]. IANA is requested to make the 230 following allocation in the aforementioned registry. 232 Bit Description Reference 233 TBD LSP Control Request Flag (c-bit) This document 235 7. Manageability Considerations 237 All manageability requirements and considerations listed in [RFC5440] 238 and [I-D.ietf-pce-stateful-pce] apply to PCEP protocol extensions 239 defined in this document. In addition, requirements and 240 considerations listed in this section apply. 242 7.1. Control of Function and Policy 244 A PCE or PCC implementation SHOULD allow the operator to configure 245 the policy based on which it honor the request to control the LSPs. 246 Further, the operator MAY be to be allowed to trigger the LSP control 247 request at the PCE. 249 7.2. Information and Data Models 251 The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to 252 include mechanism to trigger the LSP control request. 254 7.3. Liveness Detection and Monitoring 256 Mechanisms defined in this document do not imply any new liveness 257 detection and monitoring requirements in addition to those already 258 listed in [RFC5440]. 260 7.4. Verify Correct Operations 262 Mechanisms defined in this document do not imply any new operation 263 verification requirements in addition to those already listed in 264 [RFC5440] and [I-D.ietf-pce-stateful-pce]. 266 7.5. Requirements On Other Protocols 268 Mechanisms defined in this document do not imply any new requirements 269 on other protocols. 271 7.6. Impact On Network Operations 273 Mechanisms defined in [RFC5440] and [I-D.ietf-pce-stateful-pce] also 274 apply to PCEP extensions defined in this document. Further, the 275 mechanism described in this document can help the operator to request 276 control of the LSPs at a particular PCE. 278 8. Acknowledgements 280 Thanks to Jonathan Hardwick to remind the authors to not use 281 suggested values in IANA section. 283 9. References 285 9.1. Normative References 287 [I-D.ietf-pce-stateful-pce] 288 Crabbe, E., Minei, I., Medved, J., and R. Varga, "PCEP 289 Extensions for Stateful PCE", draft-ietf-pce-stateful- 290 pce-21 (work in progress), June 2017. 292 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 293 Requirement Levels", BCP 14, RFC 2119, 294 DOI 10.17487/RFC2119, March 1997, 295 . 297 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 298 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 299 DOI 10.17487/RFC5440, March 2009, 300 . 302 9.2. Informative References 304 [I-D.ietf-pce-pce-initiated-lsp] 305 Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP 306 Extensions for PCE-initiated LSP Setup in a Stateful PCE 307 Model", draft-ietf-pce-pce-initiated-lsp-10 (work in 308 progress), June 2017. 310 [I-D.ietf-pce-pcep-yang] 311 Dhody, D., Hardwick, J., Beeram, V., and j. 312 jefftant@gmail.com, "A YANG Data Model for Path 313 Computation Element Communications Protocol (PCEP)", 314 draft-ietf-pce-pcep-yang-05 (work in progress), June 2017. 316 [I-D.ietf-pce-pceps] 317 Lopez, D., Dios, O., Wu, Q., and D. Dhody, "Secure 318 Transport for PCEP", draft-ietf-pce-pceps-14 (work in 319 progress), May 2017. 321 [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 322 Element (PCE) Communication Protocol Generic 323 Requirements", RFC 4657, DOI 10.17487/RFC4657, September 324 2006, . 326 [RFC8051] Zhang, X., Ed. and I. Minei, Ed., "Applicability of a 327 Stateful Path Computation Element (PCE)", RFC 8051, 328 DOI 10.17487/RFC8051, January 2017, 329 . 331 Authors' Addresses 333 Aswatnarayan Raghuram 334 AT&T 335 200 S Laurel Aevenue 336 Middletown, NJ 07748 337 USA 339 Email: ar2521@att.com 341 Al Goddard 342 AT&T 343 200 S Laurel Aevenue 344 Middletown, NJ 07748 345 USA 347 Email: ag6941@att.com 349 Chaitanya Yadlapalli 350 AT&T 351 200 S Laurel Aevenue 352 Middletown, NJ 07748 353 USA 355 Email: cy098d@att.com 357 Jay Karthik 358 Cisco Systems, Inc. 359 125 High Street 360 Boston, Massachusetts 02110 361 USA 363 Email: jakarthi@cisco.com 365 Siva Sivabalan 366 Cisco Systems, Inc. 367 2000 Innovation Drive 368 Kanata, Ontario K2K 3E8 369 Canada 371 Email: msiva@cisco.com 372 Jon Parker 373 Cisco Systems, Inc. 374 2000 Innovation Drive 375 Kanata, Ontario K2K 3E8 376 Canada 378 Email: jdparker@cisco.com 380 Dhruv Dhody 381 Huawei Technologies 382 Divyashree Techno Park, Whitefield 383 Bangalore, Karnataka 560066 384 India 386 Email: dhruv.ietf@gmail.com