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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) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 PCE Working Group Y. Lee 2 Internet Draft Samsung 3 Intended status: Standard Track H. Zheng (Editor) 4 Expires: September 2, 2020 Huawei Technologies 5 R. Casellas 6 R. Vilalta 7 CTTC 8 D. Ceccarelli 9 F. Lazzeri 10 Ericsson 12 March 2, 2020 14 PCEP Extension for Flexible Grid Networks 16 draft-ietf-pce-flexible-grid-03 18 Abstract 20 This document provides the Path Computation Element Communication 21 Protocol (PCEP) extensions for the support of Routing and Spectrum 22 Assignment (RSA) in Flexible Grid networks. 24 Status of this Memo 26 This Internet-Draft is submitted to IETF in full conformance with 27 the provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF), its areas, and its working groups. Note that 31 other groups may also distribute working documents as Internet- 32 Drafts. 34 Internet-Drafts are draft documents valid for a maximum of six 35 months and may be updated, replaced, or obsoleted by other documents 36 at any time. It is inappropriate to use Internet-Drafts as 37 reference material or to cite them other than as "work in progress." 39 The list of current Internet-Drafts can be accessed at 40 http://www.ietf.org/ietf/1id-abstracts.txt 42 The list of Internet-Draft Shadow Directories can be accessed at 43 http://www.ietf.org/shadow.html. 45 This Internet-Draft will expire on September 2, 2020. 47 Copyright Notice 49 Copyright (c) 2020 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with 57 respect to this document. Code Components extracted from this 58 document must include Simplified BSD License text as described in 59 Section 4.e of the Trust Legal Provisions and are provided without 60 warranty as described in the Simplified BSD License. 62 Table of Contents 64 1. Terminology ................................................. 3 65 2. Requirements Language ....................................... 3 66 3. Introduction ................................................ 3 67 4. Spectrum Assignment (SA) Object ............................. 4 68 4.1. Frequency-Slot Selection TLV ........................... 6 69 4.2. Frequency-slot Restriction Constraint TLV ............... 8 70 4.2.1. Frequency-Slot Restriction Field .................. 10 71 5. Encoding of a RSA Path Reply ................................ 10 72 5.1. Error Indicator........................................ 11 73 5.2. NO-PATH Indicator ..................................... 11 74 6. Manageability Considerations ................................ 12 75 6.1. Control of Function and Policy ......................... 12 76 6.2. Information and Data Models ............................ 12 77 6.3. Verifying Correct Operation ............................ 12 78 6.4. Requirements on Other Protocols and Functional Components13 79 6.5. Impact on Network Operation ............................ 13 80 7. Security Considerations ..................................... 13 81 8. IANA Considerations ........................................ 13 82 8.1. New PCEP Object........................................ 13 83 8.2. New PCEP TLV: Frequency Slot Selection TLV ............. 13 84 8.3. New PCEP TLV: Frequency Slot Restriction Constraint TLV . 14 85 8.4. New PCEP TLV: Spectrum Allocation TLV .................. 14 86 8.5. New No-Path Reasons .................................... 14 87 8.6. New Error-Types and Error-Values ....................... 15 88 8.7. New Error-Values for Existing Error Type (24) .......... 15 89 9. References ................................................. 16 90 9.1. Normative References ................................... 16 91 9.2. Informative References ................................. 16 92 10. Contributors .............................................. 17 93 Authors' Addresses ............................................ 18 95 1. Terminology 97 This document uses the terminology defined in [RFC4655], [RFC5440] 98 and [RFC7698]. 100 2. Requirements Language 102 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 103 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 104 "OPTIONAL" in this document are to be interpreted as described in 105 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 106 capitals, as shown here. 108 3. Introduction 110 [RFC4655] defines a Path Computation Element (PCE) based path 111 computation architecture and explains how a Path Computation Element 112 (PCE) may compute Label Switched Paths (LSP) in Multiprotocol Label 113 Switching Traffic Engineering (MPLS-TE) and Generalized MPLS (GMPLS) 114 networks at the request of Path Computation Clients (PCCs). A PCC 115 is said to be any network component that makes such a request and 116 may be, for instance, an Optical Switching Element within a 117 Wavelength Division Multiplexing (WDM) network. The PCE, itself, 118 can be located anywhere within the network, and may be within an 119 optical switching element, a Network Management System (NMS) or 120 Operational Support System (OSS), or may be an independent network 121 server. 123 The PCE communications Protocol (PCEP) is the communication protocol 124 used between a PCC and a PCE, and can also be used between 125 cooperating PCEs. [RFC4657] sets out the common protocol 126 requirements for PCEP. Additional application-specific requirements 127 for PCEP are deferred to separate documents. 129 [PCEP-WSON] provides the PCEP extensions for the support of Routing 130 and Wavelength Assignment (RWA) in Wavelength Switched Optical 131 Networks (WSON) based on the requirements specified in [RFC6163] and 132 [RFC7449]. 134 To allow efficient allocation of optical spectral bandwidth for 135 systems that have high bit-rates, the International 136 Telecommunication Union Telecommunication Standardization Sector 137 (ITU-T) has extended its Recommendations [G.694.1] and [G.872] to 138 include a new Dense Wavelength Division Multiplexing (DWDM) grid by 139 defining a set of nominal central frequencies, channel spacings, and 140 the concept of the "frequency slot". In such an environment, a data- 141 plane connection is switched based on allocated, variable-sized 142 frequency ranges within the optical spectrum, creating what is known 143 as a flexible grid (flexi-grid). [RFC7698] provides Framework and 144 Requirements for GMPLS-Based Control of Flexi-Grid Dense Wavelength 145 Division Multiplexing (DWDM) Networks. 147 The terms "Routing and Spectrum Assignment" (RSA) is introduced in 148 [RFC7698] to refer to the process determines a route and frequency 149 slot for an LSP. Hence, when a route is computed, the spectrum 150 assignment process determines the central frequency and slot width. 151 The term "Spectrum Switched Optical Networks" is also introduced in 152 [RFC7698] to refer to a flexi-grid enabled DWDM network, which can 153 be controlled by a GMPLS or PCE control plane. 155 This document provides PCEP extensions to support RSA in SSONs. 157 Figure 2 shows one typical PCE based implementation, which is 158 referred to as the Combined Routing and Spectrum Assignment (R&SA) 159 [RFC7698]. With this architecture, the two processes of routing and 160 spectrum assignment are accessed via a single PCE. This architecture 161 is the base architecture from which the PCEP extensions are 162 specified in this document. 164 +----------------------------+ 165 +-----+ | +-------+ +--+ | 166 | | | |Routing| |SA| | 167 | PCC |<----->| +-------+ +--+ | 168 | | | | 169 +-----+ | PCE | 170 +----------------------------+ 172 Figure 1 Combined Process (R&SA) architecture 174 4. Spectrum Assignment (SA) Object 176 This document aligns with GMPLS extensions for PCEP [PCEP-GMPLS] for 177 generic property such as label, label-set and label assignment 178 noting that frequency is a type of label. Frequency restrictions and 179 constraints are also formulated in terms of labels per [RFC7579]. 181 Spectrum allocation can be performed by the PCE by different means: 183 (a) By means of Explicit Label Control (ELC) where the PCE 184 allocates which label to use for each interface/node along the 185 path. 187 (b) By means of a Label Set where the PCE provides a range of 188 potential frequency slots to allocate by each node along the path. 190 Option (b) allows distributed spectrum allocation (performed during 191 signaling) to complete spectrum assignment. 193 Additionally, given a range of potential spectrums to allocate, a PC 194 Request SHOULD convey the heuristic / mechanism to the allocation. 196 The format Routing Backus-Naur Form (RBNF) [RFC5511] of a PCReq 197 message per [RFC5440] after incorporating the Spectrum Assignment 198 (SA) object is as follows: 200 ::= 202 [] 204 206 Where: 208 ::=[] 210 ::= 212 214 [ ] 216 [other optional objects...] 218 If the SA object is present in the request, it MUST be encoded after 219 the GENERALIZED ENDPOINTS object. 221 SA Object-Class is (TBD1) (To be assigned by IANA). 223 SA Object-Type is 1. 225 The format of the Spectrum Assignment (SA) object body is as 226 follows: 228 0 1 2 3 229 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 1 230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 231 | Reserved | Flags |M| 232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 233 | Frequency-Slot Selection TLV | 234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 235 | Frequency-Slot Restriction Constraint TLV | 236 . . 237 . . 238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 239 // Optional TLVs // 240 | | 241 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 243 Figure 2 SA Object 245 o Reserved (16 bits) 247 o Flags (16 bits) 249 One Flag bit is allocated as follows: 251 M (Mode - 1 bit): M bit is used to indicate the mode of spectrum 252 assignment. When M bit is set to 1, this indicates that the 253 spectrum assigned by the PCE must be explicit. That is, the 254 selected way to convey the allocated spectrum is by means of 255 Explicit Label Control (ELC) [RFC4003] for each hop of a 256 computed LSP. Otherwise, the spectrum assigned by the PCE 257 needs not be explicit (i.e., it can be suggested in the form 258 of label set objects in the corresponding response, to allow 259 distributed SA. In such case, the PCE MUST return a Label Set 260 Field as described in Section 2.6 of [RFC7579] in the 261 response. See Section 5 of this document for the encoding 262 discussion of a Label Set Field in a PCRep message. 264 4.1. Frequency-Slot Selection TLV 266 The Frequency-Slot Selection TLV is used to indicate the frequency- 267 slot selection constraint in regard to the order of frequency-slot 268 assignment to be returned by the PCE. This TLV is only applied when 269 M bit is set in the SA Object specified in Section 4. This TLV 270 SHOULD NOT be present and MUST be ignored when the M bit is cleared. 272 The Frequency-Slot Selection sub-TLV value field is defined as: 274 0 1 2 3 275 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 1 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 |S| FSA Method | Reserved | 278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 279 Where: 281 Frequency-Slot Assignment (FSA) Method (7 bits): 283 0: unspecified (any); This does not constrain the SA method 284 used by a PCC This value is implied when the 285 Frequency-Slot Selection sub-TLV is absent. 287 1: First-Fit. All the feasible frequency slots are numbered3 288 (based on "n" parameter), and this SA method chooses the 289 available frequency-slot with the lowest index, where "n" is 290 the parameter in f = 193.1 THz + n x 0.00625 THz where 193.1 291 THz is the ITU-T "anchor frequency" and "n" is a positive 292 integer including 0 [RFC7698]. 294 2: Random. This SA method chooses a feasible frequency-slot 295 value of "n" randomly. 297 3-127: Unassigned. 299 S (Symmetry, 1 bit): This flag is only meaningful when the request 300 is for a bidirectional LSP (see [RFC5440]). 302 0 denotes requiring the same frequency-slot in both directions; 303 1 denotes that different spectrums on both directions are 304 allowed. 306 IANA is to allocate a new PCEP TLV type, Frequency-Slot Selection 307 TLV (TBD2) in the "PCEP TLV Type Indicators" subregistry 308 (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type- 309 indicators). 311 The processing rules for this TLV are as follows: 313 If a PCE does not support the attribute(s), its behavior is 314 specified below: 316 - S bit clear not supported: a PathErr MUST be generated with 317 The Error Code "Routing Problem" (24) with error sub-code 318 "Unsupported Frequency slot Selection Symmetry value" (TBD3). 320 - FSA method not supported: a PathErr MUST be generated with the 321 Error Code "Routing Problem" (24) with error sub-code 322 "Unsupported Frequency Slot Assignment value" (TBD4). 324 4.2. Frequency-slot Restriction Constraint TLV 326 For any request that contains a Frequency-slot assignment, the 327 requester (PCC) must be able to specify a restriction on the 328 frequency-slots to be used. This restriction is to be interpreted by 329 the PCE as a constraint on the tuning ability of the origination 330 laser transmitter or on any other maintenance related constraints. 332 The format of the Frequency-Slot Restriction Constraint TLV is as 333 follows: 335 ::= 337 ( 339 )... 341 Where 343 ::= [] 345 See Section 4.3.1 in [PCEP-WSON] for the encoding of the Link 346 Identifiers Field. 348 IANA is to allocate a new PCEP TLV, the Frequency slot Restriction 349 Constraint TLV type (TBD5). This TLV MAY appear more than once to be 350 able to specify multiple restrictions. 352 The TLV data is defined as follows: 354 0 1 2 3 355 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 1 356 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 357 | Action | Count | Reserved | 358 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 359 | Link Identifiers | 360 | . . . | 361 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 362 | Frequency Slot Restriction Field | 363 // . . . . // 364 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 366 Figure 3 spectrum Restriction Constraint TLV Encoding 368 o Action: 8 bits 370 0 - Inclusive List indicates that one or more link identifiers 371 are included in the Link Set. Each identifies a separate link 372 that is part of the set. 374 1 - Inclusive Range indicates that the Link Set defines a 375 range of links. It contains two link identifiers. The first 376 identifier indicates the start of the range (inclusive). The 377 second identifier indicates the end of the range (inclusive). 378 All links with numeric values between the bounds are 379 considered to be part of the set. A value of zero in either 380 position indicates that there is no bound on the corresponding 381 portion of the range. Note that the Action field can be set to 382 0 when unnumbered link identifier is used. 384 o Count: The number of the link identifiers (8 bits) 386 Note that a PCC MAY add a frequency slot restriction that applies to 387 all links by setting the Count field to zero and specifying just a 388 set of frequency slots. 390 Note that all link identifiers in the same list must be of the same 391 type. 393 o Reserved: Reserved for future use (16 bits) 395 o Link Identifiers: Identifies each link ID for which restriction 396 is applied. The length is dependent on the link format and the Count 397 field. See Section 4.3.1 in [PCEP-WSON] for Link Identifier 398 encoding. 400 4.2.1. Frequency-Slot Restriction Field 402 The Frequency-Slot Restriction Field of the Frequency slot 403 restriction TLV is encoded as defined in section 4.2 of [RFC8363]. 405 5. Encoding of a RSA Path Reply 407 This section provides the encoding of a RSA Path Reply, in the 408 PCRep/PCUpd message, for frequency slot allocation as discussed in 409 Section 4. Spectrum Allocation TLV IANA is to allocate a new PCEP 410 TLV type, the Spectrum Allocation TLV type (TBD6). The TLV data is 411 defined as follows: 413 0 1 2 3 414 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 1 415 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 416 | Type | Length |M| 417 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 | Link Identifier | 419 | . . . | 420 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 | Allocated Spectrum(s) | 422 // . . . . // 423 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 425 Figure 4 Spectrum Allocation TLV Encoding 427 o Type (16 bits): The type of the TLV. 429 o Length (15 bits): The length of the TLV including the Type and 430 Length fields. 432 o M (Mode): 1 bit 434 - 0 indicates the allocation is under Explicit Label Control. 436 - 1 indicates the allocation is expressed in Label Sets. 438 Note that all link identifiers in the same list must be of the same 439 type. 441 o Link Identifier (variable): Identifies the interface to which 442 assignment spectrum(s) is applied. See Section 3.3 for Link 443 Identifier encoding. 445 o Allocated Spectrum(s) (variable): Indicates the allocated 446 spectrum(s) to the link identifier. See Section 3.3.1 for encoding 447 details. 449 This TLV is encoded as an attributes TLV, per [RFC5420], which is 450 carried in the ERO LSP Attribute Subobjects per [RFC7570]. 452 5.1. Error Indicator 454 To indicate errors associated with the RSA request, a new Error Type 455 (TDB) and subsequent error-values are defined as follows for 456 inclusion in the PCEP-ERROR Object: 458 A new Error-Type (TBD7) and subsequent error-values are defined as 459 follows: 461 Error-Type=TBD7; Error-value=1: if a PCE receives a RSA 462 request and the PCE is not capable of processing the request 463 due to insufficient memory, the PCE MUST send a PCErr message 464 with a PCEP-ERROR Object (Error-Type=TDB) and an Error- 465 value(Error-value=1). The PCE stops processing the request. 466 The corresponding RSA request MUST be cancelled at the PCC. 468 Error-Type=TBD7; Error-value=2: if a PCE receives a RSA 469 request and the PCE is not capable of RSA computation, the PCE 470 MUST send a PCErr message with a PCEP-ERROR Object (Error- 471 Type=TDB) and an Error-value (Error-value=2). The PCE stops 472 processing the request. The corresponding RSA computation 473 MUST be cancelled at the PCC. 475 5.2. NO-PATH Indicator 477 To communicate the reason(s) for not being able to find RSA for the 478 path request, the NO-PATH object can be used in the corresponding 479 response. The format of the NO-PATH object body is defined in 480 [RFC5440]. The object may contain a NO-PATH-VECTOR TLV to provide 481 additional information about why a path computation has failed. 483 One new bit flag is defined to be carried in the Flags field in the 484 NO-PATH-VECTOR TLV carried in the NO-PATH Object. 486 Bit TBD8: When set, the PCE indicates no feasible route was 487 found that meets all the constraints (e.g., spectrum 488 restriction, etc.) associated with RSA. 490 6. Manageability Considerations 492 Manageability of SSON Routing and Spectrum Assignment (RSA) with PCE 493 must address the following considerations: 495 6.1. Control of Function and Policy 497 In addition to the parameters already listed in Section 8.1 of 498 [RFC5440], a PCEP implementation SHOULD allow configuring the 499 following PCEP session parameters on a PCC: 501 The ability to send a Flexi-Grid RSA request. 503 In addition to the parameters already listed in Section 8.1 of 504 [RFC5440], a PCEP implementation SHOULD allow configuring the 505 following PCEP session parameters on a PCE: 507 The support for Flexi-Grid RSA . 509 A set of Flexi-Grid RSA specific policies (authorized sender, 510 request rate limiter, etc). 512 These parameters may be configured as default parameters for any 513 PCEP session the PCEP speaker participates in, or may apply to a 514 specific session with a given PCEP peer or a specific group of 515 sessions with a specific group of PCEP peers. 517 6.2. Information and Data Models 519 Extensions to the PCEP YANG module may include to cover the Flexi- 520 Grid RSA information introduced in this document. Liveness Detection 521 and Monitoring Mechanisms defined in this document do not imply any 522 new liveness detection and monitoring requirements in addition to 523 those already listed in section 8.3 of [RFC5440]. 525 6.3. Verifying Correct Operation 527 Mechanisms defined in this document do not imply any new 528 verification requirements in addition to those already listed in 529 section 8.4 of [RFC5440]. 531 6.4. Requirements on Other Protocols and Functional Components 533 The PCE Discovery mechanisms ([RFC5089] and [RFC5088]) may be used 534 to advertise Flexi-Grid RSA path computation capabilities to PCCs. 535 This draft has requirements on other protocols (ERO objects, etc. 536 which are under TEAS or CCAMP.) 538 6.5. Impact on Network Operation 540 Mechanisms defined in this document do not imply any new network 541 operation requirements in addition to those already listed in 542 section 8.6 of [RFC5440]. 544 7. Security Considerations 546 This document has no requirement for a change to the security models 547 within PCEP. However, the additional information distributed in 548 order to address the RSA problem represents a disclosure of network 549 capabilities that an operator may wish to keep private. 550 Consideration should be given to securing this information. 552 8. IANA Considerations 554 IANA is requested to make allocations from the sub-registries as 555 described in the following sections. 557 8.1. New PCEP Object 559 As described in Section 4.1, a new PCEP Object is defined to carry 560 frequency-slot assignment related constraints. IANA is to allocate 561 the following from "PCEP Objects" sub-registry 562 (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-objects): 564 Object Class Name Object Reference 565 Value Type 566 --------------------------------------------------------- 568 TBD1 SA 1: Spectrum Assignment [This.I-D] 570 8.2. New PCEP TLV: Frequency Slot Selection TLV 572 As described in Sections 4.2, a new PCEP TLV is defined to indicate 573 spectrum selection constraints. IANA is to allocate this new TLV 574 from the "PCEP TLV Type Indicators" subregistry 575 (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type- 576 indicators). 578 Value Description Reference 579 --------------------------------------------------------- 580 TBD2 Spectrum Selection [This.I-D] 582 8.3. New PCEP TLV: Frequency Slot Restriction Constraint TLV 584 As described in Section 4.3, a new PCEP TLV is defined to indicate 585 wavelength restriction constraints. IANA is to allocate this new TLV 586 from the "PCEP TLV Type Indicators" subregistry 587 (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type- 588 indicators). 590 Value Description Reference 591 --------------------------------------------------------- 592 TBD5 Frequency Slot Restriction [This.I-D] 593 Constraint 595 8.4. New PCEP TLV: Spectrum Allocation TLV 597 As described in Section 5, a new PCEP TLV is defined to indicate the 598 allocation of freq-slots(s) by the PCE in response to a request by 599 the PCC. IANA is to allocate this new TLV from the "PCEP TLV Type 600 Indicators" subregistry 601 (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-tlv-type- 602 indicators). 604 Value Description Reference 605 --------------------------------------------------------- 606 TBD6 Spectrum Allocation [This.I-D] 608 8.5. New No-Path Reasons 610 As described in Section 4.3, a new bit flag are defined to be 611 carried in the Flags field in the NO-PATH-VECTOR TLV carried in the 612 NO-PATH Object. This flag, when set, indicates that no feasible 613 route was found that meets all the RSA constraints (e.g., spectrum 614 restriction, signal compatibility, etc.) associated with a RSA path 615 computation request. 617 IANA is to allocate this new bit flag from the "PCEP NO-PATH-VECTOR 618 TLV Flag Field" subregistry 619 (http://www.iana.org/assignments/pcep/pcep.xhtml#no-path-vector- 620 tlv). 622 Bit Description Reference 623 ----------------------------------------------------- 624 TBD8 No RSA constraints met [This.I-D] 626 8.6. New Error-Types and Error-Values 628 As described in Section 5.1, new PCEP error codes are defined for 629 WSON RWA errors. IANA is to allocate from the ""PCEP-ERROR Object 630 Error Types and Values" sub-registry 631 (http://www.iana.org/assignments/pcep/pcep.xhtml#pcep-error-object). 633 Error- Meaning Error-Value Reference 634 Type 635 --------------------------------------------------------------- 637 TBD7 Flexi-Grid RSA Error 1: Insufficient [This.I-D] 638 Memory 639 2: RSA computation [This.I-D] 641 8.7. New Error-Values for Existing Error Type (24) 643 As discussed in Section 4.1, two new PathErr values for the Existing 644 Error Type (24) are to be allocated: 646 Meaning Error-Value Reference 648 --------------------------------------------------------------- 649 Unsupported Frequency slot 650 Selection Symmetry value TBD3 [This.I-D] 652 Unsupported Frequency Slot 653 Assignment value TBD4 [This.I-D] 655 9. References 657 9.1. Normative References 659 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 660 Requirement Levels", BCP 14, RFC 2119, March 1997. 662 [RFC4003] Berger, L., "GMPLS Signaling Procedure for Egress 663 Control", RFC 4003, February 2005. 665 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 666 Element (PCE) communication Protocol", RFC 5440, March 667 2009. 669 [RFC5511] A. Farrel, "Routing Backus-Naur Form (RBNF): A Syntax Used 670 to Form Encoding Rules in Various Routing Protocol 671 Specifications", RFC 5511, April 2009. 673 [RFC5088] Le Roux, JL, JP. Vasseur, Y. Ikejiri, and R. Zhang, "OSPF 674 Protocol Extensions for Path Computation Element (PCE) 675 Discovery," RFC 5088, January 2008. 677 [RFC5089] Le Roux, JL, JP. Vasseur, Y. Ikejiri, and R. Zhang, "IS-IS 678 Protocol Extensions for Path Computation Element (PCE) 679 Discovery," RFC 5089, January 2008. 681 [RFC8174] B. Leiba, "Ambiguity of Uppercase vs Lowercase in RFC 2119 682 Key Words", RFC 8174, May 2017. 684 9.2. Informative References 686 [PCEP-GMPLS] Margaria, et al., "PCEP extensions for GMPLS", draft- 687 ietf-pce-gmpls-pcep-extensions, work in progress. 689 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 690 Element (PCE)-Based Architecture", RFC 4655, August 2006. 692 [RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE) 693 Communication Protocol Generic Requirements", RFC 4657, 694 September 2006. 696 [RFC5420] Farrel, A. "Encoding of Attributes for MPLS LSP 697 Establishment Using Resource Reservation Protocol Traffic 698 Engineering (RSVP-TE)", RFC 5420, February 2009. 700 [RFC6163] Lee, Y. and Bernstein, G. (Editors), and W. Imajuku, 701 "Framework for GMPLS and PCE Control of Wavelength 702 Switched Optical Networks", RFC 6163, March 2011. 704 [RFC7449] Lee, Y., et. al., "PCEP Requirements for WSON Routing and 705 Wavelength Assignment", RFC 7449, February 2015. 707 [RFC7570] Margaria, et al., "Label Switched Path (LSP) Attribute in 708 the Explicit Route Object (ERO)", RFC 7570, July 2015. 710 [RFC7579] Bernstein and Lee, "General Network Element Constraint 711 Encoding for GMPLS Controlled Networks", RFC 7579, June 712 2015. 714 [PCEP-WSON] Y. Lee (Ed.), and R. Casellas (Ed.), "PCEP Extension for 715 WSON Routing and Wavelength Assignment", draft-ietf-pce- 716 wson-rwa-ext, work in progress. 718 [RFC7698] O. Gonzalez de Dios, R. Casellas, editors, "Framework and 719 Requirements for GMPLS-Based Control of Flexi-Grid Dense 720 Wavelength Division Multiplexing (DWDM) Networks", RFC 721 7698, November 2015. 723 [RFC8363] X. Zhang, H. Zheng, R. Casellas, O. Gonzalez de Dios, D. 724 Ceccarelli, "GMPLS OSPF-TE Extensions in Support of Flexi- 725 Grid Dense Wavelength Division Multiplexing (DWDM) 726 Networks", RFC8363, May 2018. 728 [G.694.1] "Spectral grids for WDM applications: DWDM frequency 729 grid", ITU-T G.694.1, February 2012. 731 [G.872] "Architecture of optical transport networks", ITU-T G.872, 732 January 2017. 734 10. Contributors 735 Authors' Addresses 737 Young Lee 738 Samsung 739 Email: younglee.tx@gmail.com 741 Haomian Zheng 742 Huawei Technologies 743 Email: zhenghaomian@huawei.com 745 Ramon Casellas 746 CTTC 747 Av. Carl Friedrich Gauss n7 748 Castelldefels, Barcelona 08860 749 Spain 750 Email: ramon.casellas@cttc.es 752 Ricard Vilalta 753 CTTC 754 Email: ricard.vilalta@cttc.es 756 Daniele Ceccarelli 757 Ericsson AB 758 Gronlandsgatan 21 759 Kista - Stockholm 760 Email: daniele.ceccarelli@ericsson.com 762 Francesco Lazzeri 763 Ericsson 764 Via Melen 77 765 Genova - Italy 766 Email: francesco.lazzeri@ericsson.com