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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group Y. Lee, Ed. 2 Internet Draft Huawei Technologies 4 Intended status: Standard R. Casellas, Ed. 5 Expires: January 2014 CTTC 7 July 12, 2013 9 PCEP Extension for WSON Routing and Wavelength Assignment 11 draft-ietf-pce-wson-rwa-ext-01.txt 13 Abstract 15 This document provides the Path Computation Element communication 16 Protocol (PCEP) extensions for the support of Routing and Wavelength 17 Assignment (RWA) in Wavelength Switched Optical Networks (WSON). 18 Lightpath provisioning in WSONs requires a routing and wavelength 19 assignment (RWA) process. From a path computation perspective, 20 wavelength assignment is the process of determining which wavelength 21 can be used on each hop of a path and forms an additional routing 22 constraint to optical light path computation. 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 41 The list of Internet-Draft Shadow Directories can be accessed at 42 http://www.ietf.org/shadow.html. 44 This Internet-Draft will expire on January 12, 2009. 46 Copyright Notice 48 Copyright (c) 2013 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with 56 respect to this document. Code Components extracted from this 57 document must include Simplified BSD License text as described in 58 Section 4.e of the Trust Legal Provisions and are provided without 59 warranty as described in the Simplified BSD License. 61 Table of Contents 63 1. Terminology....................................................3 64 2. Requirements Language..........................................3 65 3. Introduction...................................................3 66 4. Encoding of a RWA Path Request.................................6 67 4.1. Wavelength Assignment (WA) Object.........................6 68 4.2. Wavelength Restriction Constraint TLV.....................8 69 4.2.1. Link Identifier Entry...............................10 70 4.2.2. Wavelength Restriction Field........................12 71 4.3. Signal processing capability restrictions................12 72 4.3.1. Signal Processing Exclusion XRO Sub-Object..........13 73 4.3.2. IRO sub-object: signal processing inclusion.........14 74 5. Encoding of a RWA Path Reply..................................14 75 5.1. Error Indicator..........................................14 76 5.2. NO-PATH Indicator........................................15 77 6. Manageability Considerations..................................15 78 6.1. Control of Function and Policy...........................15 79 6.2. Information and Data Models, e.g. MIB module.............16 80 6.3. Liveness Detection and Monitoring........................16 81 6.4. Verifying Correct Operation..............................16 82 6.5. Requirements on Other Protocols and Functional Components16 83 6.6. Impact on Network Operation..............................17 84 7. Security Considerations.......................................17 85 8. IANA Considerations...........................................17 86 9. Acknowledgments...............................................17 87 10. References...................................................17 88 10.1. Informative References..................................17 89 11. Contributors.................................................19 90 Authors' Addresses...............................................20 91 Intellectual Property Statement..................................20 92 Disclaimer of Validity...........................................21 94 1. Terminology 96 This document uses the terminology defined in [RFC4655], and 97 [RFC5440]. 99 2. Requirements Language 101 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 102 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 103 document are to be interpreted as described in [RFC2119]. 105 3. Introduction 107 [RFC4655] defines a PCE based path computation architecture and 108 explains how a Path Computation Element (PCE) may compute Label 109 Switched Paths (LSP) in Multiprotocol Label Switching Traffic 110 Engineering (MPLS-TE) and Generalized MPLS (GMPLS) networks at the 111 request of Path Computation Clients (PCCs). A PCC is said to be any 112 network component that makes such a request and may be, for 113 instance, an Optical Switching Element within a Wavelength Division 114 Multiplexing (WDM) network. The PCE, itself, can be located 115 anywhere within the network, and may be within an optical switching 116 element, a Network Management System (NMS) or Operational Support 117 System (OSS), or may be an independent network server. 119 The PCE communications Protocol (PCEP) is the communication protocol 120 used between a PCC and a PCE, and may also be used between 121 cooperating PCEs. [RFC4657] sets out the common protocol 122 requirements for PCEP. Additional application-specific requirements 123 for PCEP are deferred to separate documents. 125 This document provides the PCEP extensions for the support of 126 Routing and Wavelength Assignment (RWA) in Wavelength Switched 127 Optical Networks (WSON) based on the requirements specified in [PCE- 128 RWA]. 130 WSON refers to WDM based optical networks in which switching is 131 performed selectively based on the wavelength of an optical signal. 132 In this document, it is assumed that wavelength converters require 133 electrical signal regeneration. Consequently, WSONs can be 134 transparent (A transparent optical network is made up of optical 135 devices that can switch but not convert from one wavelength to 136 another, all within the optical domain) or translucent (3R 137 regenerators are sparsely placed in the network). 139 A LSC Label Switched Path (LSP) may span one or several transparent 140 segments, which are delimited by 3R regenerators (typically with 141 electronic regenerator and optional wavelength conversion). Each 142 transparent segment or path in WSON is referred to as an optical 143 path. An optical path may span multiple fiber links and the path 144 should be assigned the same wavelength for each link. In such case, 145 the optical path is said to satisfy the wavelength-continuity 146 constraint. Figure 1 illustrates the relationship between a LSC LSP 147 and transparent segments (optical paths). 149 +---+ +-----+ +-----+ +-----+ +-----+ 150 | |I1 | | | | | | I2| | 151 | |o------| |-------[(3R) ]------| |--------o| | 152 | | | | | | | | | | 153 +---+ +-----+ +-----+ +-----+ +-----+ 154 [X LSC] [LSC LSC] [LSC LSC] [LSC X] SwCap 155 <-------> <-------> <-----> <-------> 156 <-----------------------><----------------------> 157 Transparent Segment Transparent Segment 158 <-------------------------------------------------> 159 LSC LSP 161 Figure 1 Illustration of a LSC LSP and transparent segments 163 Note that two optical paths within a WSON LSP need not operate on 164 the same wavelength (due to the wavelength conversion capabilities). 165 Two optical paths that share a common fiber link cannot be assigned 166 the same wavelength. To do otherwise would result in both signals 167 interfering with each other. Note that advanced additional 168 multiplexing techniques such as polarization based multiplexing are 169 not addressed in this document since the physical layer aspects are 170 not currently standardized. Therefore, assigning the proper 171 wavelength on a lightpath is an essential requirement in the optical 172 path computation process. 174 When a switching node has the ability to perform wavelength 175 conversion, the wavelength-continuity constraint can be relaxed, and 176 a LSC Label Switched Path (LSP) may use different wavelengths on 177 different links along its route from origin to destination. It is, 178 however, to be noted that wavelength converters may be limited due 179 to their relatively high cost, while the number of WDM channels that 180 can be supported in a fiber is also limited. As a WSON can be 181 composed of network nodes that cannot perform wavelength conversion, 182 nodes with limited wavelength conversion, and nodes with full 183 wavelength conversion abilities, wavelength assignment is an 184 additional routing constraint to be considered in all lightpath 185 computation. 187 For example (see Figure 1), within a translucent WSON, a LSC LSP may 188 be established between interfaces I1 and I2, spanning 2 transparent 189 segments (optical paths) where the wavelength continuity constraint 190 applies (i.e. the same unique wavelength MUST be assigned to the LSP 191 at each TE link of the segment). If the LSC LSP induced a Forwarding 192 Adjacency / TE link, the switching capabilities of the TE link would 193 be [X X] where X < LSC (PSC, TDM, ...). 195 This document aligns with GMPLS extensions for PCEP [PCEP-GMPLS] for 196 generic property such as label, label-set and label assignment 197 noting that wavelength is a type of label. Wavelength restrictions 198 and constraints are also formulated in terms of labels per [GEN- 199 ENCODE]. 201 The optical modulation properties, which are also referred to as 202 signal compatibility, are already considered in signaling in [RWA- 203 Encode] and [WSON-OSPF]. In order to improve the signal quality and 204 limit some optical effects several advanced modulation processing 205 are used. Those modulation properties contribute not only to optical 206 signal quality checks but also constrain the selection of sender and 207 receiver, as they should have matching signal processing 208 capabilities. This document includes signal compatibility 209 constraints as part of RWA path computation. That is, the signal 210 processing capabilities (e.g., modulation and FEC) must be 211 compatible between the sender and the receiver of the optical path 212 across all optical elements. 214 This document, however, does not address optical impairments as part 215 of RWA path computation. See [WSON-Imp] and [RSVP-Imp] for more 216 information on optical impairments and GMPLS. 218 4. Encoding of a RWA Path Request 220 Figure 2 shows one typical PCE based implementation, which is 221 referred to as the Combined Process (R&WA). With this architecture, 222 the two processes of routing and wavelength assignment are accessed 223 via a single PCE. This architecture is the base architecture from 224 which the requirements have been specified in [PCE-RWA] and the PCEP 225 extensions that are going to be specified in this document based on 226 this architecture. 228 +----------------------------+ 229 +-----+ | +-------+ +--+ | 230 | | | |Routing| |WA| | 231 | PCC |<----->| +-------+ +--+ | 232 | | | | 233 +-----+ | PCE | 234 +----------------------------+ 236 Figure 2 Combined Process (R&WA) architecture 238 4.1. Wavelength Assignment (WA) Object 240 Wavelength allocation can be performed by the PCE by different 241 means: 243 (a) By means of Explicit Label Control, in the sense that one (or 244 two) allocated labels MAY appear after an interface route subobject. 245 (b) By means of a Label Set, containing one or more allocated Labels, 246 provided by the PCE. 248 Option (b) allows distributed label allocation (performed during 249 signaling) to complete wavelength assignment. 251 Additionally, given a range of potential labels to allocate, the 252 request SHOULD convey the heuristic / mechanism to the allocation. 254 The format of a PCReq message after incorporating the WA object is 255 as follows: 257 ::= 259 [] 261 263 Where: 265 ::=[] 267 ::= 269 271 273 [other optional objects...] 275 If the WA object is present in the request, it MUST be encoded after 276 the ENDPOINTS object. 278 The format of the Wavelength Assignment (WA) object body is as 279 follows: 281 0 1 2 3 282 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 1 283 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 284 | Flags | O |M| 285 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 286 | Wavelength Restriction TLV | 287 . . 288 . . 289 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 290 // Optional TLVs // 291 | | 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 294 Figure 3 WA Object 296 o Flags (32 bits) 298 The following new flags SHOULD be set 300 . M (Mode - 1 bit): M bit is used to indicate the mode of 301 wavelength assignment. When M bit is set to 1, this indicates 302 that the label assigned by the PCE must be explicit. That is, 303 the selected way to convey the allocated wavelength is by means 304 of Explicit Label Control (ELC) [RFC4003] for each hop of a 305 computed LSP. Otherwise, the label assigned by the PCE needs 306 not be explicit (i.e., it can be suggested in the form of label 307 set objects in the corresponding response, to allow distributed 308 WA. In such case, the PCE MUST return a Label Set object as 309 described in Section 2.2 of [Gen-Encode] in the response. 311 . O (Order - 3 bits): O bit is used to indicate the wavelength 312 assignment constraint in regard to the order of wavelength 313 assignment to be returned by the PCE. This case is only applied 314 when M bit is set to "explicit." The following indicators 315 should be defined: 317 000 - Reserved 319 001 - Random Assignment 321 010 - First Fit (FF) in descending Order 323 011 - First Fit (FF) in ascending Order 325 100 - Last Fit (LF) in ascending Order 327 101 - Last Fit (LF) in descending Order 329 110 - Unspecified 331 111 - Reserved 333 4.2. Wavelength Restriction Constraint TLV 335 For any request that contains a wavelength assignment, the requester 336 (PCC) MUST be able to specify a restriction on the wavelengths to be 337 used. This restriction is to be interpreted by the PCE as a 338 constraint on the tuning ability of the origination laser 339 transmitter or on any other maintenance related constraints. Note 340 that if the LSP LSC spans different segments, the PCE MUST have 341 mechanisms to know the tunability restrictions of the involved 342 wavelength converters / regenerators, e.g. by means of the TED 343 either via IGP or NMS. Even if the PCE knows the tunability of the 344 transmitter, the PCC MUST be able to apply additional constraints to 345 the request. 347 The TLV type is TBD, recommended value is TBD. This TLV MAY appear 348 more than once to be able to specify multiple restrictions. 350 The TLV data is defined as follows: 352 ::= 354 355 ( )... 357 Where 359 ::= [] 361 ::= 363 | | 365 0 1 2 3 366 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 1 367 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 368 | Action | Count | Reserved | 369 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 370 | Link Identifiers | 371 | . . . | 372 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 373 | Wavelength Restriction Field | 374 // . . . . // 375 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 377 Figure 4 Wavelength Restriction 379 o Action: 8 bits 381 . 0 - Inclusive List indicates that one or more link identifiers 382 are included in the Link Set. Each identifies a separate link 383 that is part of the set. 385 . 1 - Inclusive Range indicates that the Link Set defines a 386 range of links. It contains two link identifiers. The first 387 identifier indicates the start of the range (inclusive). The 388 second identifier indicates the end of the range (inclusive). 389 All links with numeric values between the bounds are 390 considered to be part of the set. A value of zero in either 391 position indicates that there is no bound on the corresponding 392 portion of the range. Note that the Action field can be set to 393 0 when unnumbered link identifier is used. 395 Note that "interfaces" such as those discussed in the Interfaces MIB 396 [RFC2863] are assumed to be bidirectional. 398 o Count: The number of of the link identifiers (8 bits) 400 Note that a PCC MAY add a Wavelength restriction that applies to all 401 links by setting the Count field to zero and specifying just a set 402 of wavelengths. 404 Note that all link identifiers in the same list must be of the same 405 type. 407 o Reserved: Reserved for future use (16 bits) 409 o Link Identifiers: Identifies each link ID for which restriction 410 is applied. The length is dependent on the link format and the Count 411 field. See the following section for Link Identifier encoding. 413 4.2.1. Link Identifier Entry 415 The link identifier field can be an IPv4, IPv6 or unnumbered 416 interface ID. 418 ::= 420 | | 422 The encoding of each case is as follows: 424 IPv4 prefix Entry 426 0 1 2 3 427 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 1 428 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 429 | Type = 1 | IPv4 address (4 bytes) | 430 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 431 | IPv4 address (continued) | Prefix Length | Attribute | 432 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 434 IPv6 prefix Sub-TLV 436 0 1 2 3 437 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 1 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 439 | Type = 2 | IPv6 address (16 bytes) | 440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 441 | IPv6 address (continued) | 442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 | IPv6 address (continued) | 444 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 445 | IPv6 address (continued) | 446 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 447 | IPv6 address (continued) | Prefix Length | Attribute | 448 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 450 Unnumbered Interface ID Sub-TLV 452 0 1 2 3 453 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 1 454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 455 | Type = 4 | Reserved | Attribute | 456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 | TE Node ID | 458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 459 | Interface ID | 460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 461 4.2.2. Wavelength Restriction Field 463 The Wavelength Restriction Field of the wavelength restriction TLV 464 is encoded as a Label Set field as specified in [GEN-Encode] section 465 2.2, as shown below, with base label encoded as a 32 bit LSC label, 466 defined in [RFC6205]. See [RFC6205] for a description of Grid, C.S, 467 Identifier and n, as well as [GEN-Encode] for the details of each 468 action. 470 0 1 2 3 472 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 1 474 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 475 | Action| Num Labels | Length | 476 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 |Grid | C.S | Identifier | n | 478 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 479 | Additional fields as necessary per action | 480 | | 481 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 4.3. Signal processing capability restrictions 485 Path computation for WSON include the check of signal processing 486 capabilities, those capability MAY be provided by the IGP, however 487 this is not a MUST. Moreover, a PCC should be able to indicate 488 additional restrictions for those signal compatibility, either on 489 the endpoint or any given link. 491 The supported signal processing capabilities are the one described 492 in [RWA-Info]: 494 . Optical Interface Class List 496 . Bit rate 498 . Client signal 500 The Bit-rate restriction is already expressed in [PCEP-GMPLS] in the 501 GENERALIZED-BANDWIDTH object. 503 The client signal information can be expressed using the REQ-ADAP- 504 CAP object from the [PCEP-Layer]. 506 In order to support the Optical Interface Class information a new 507 TLV is introduced as endpoint-restriction in the END-POINTS type 508 Generalized endpoint: 510 . Optical Interface Class List TLV 512 The END-POINTS type generalized endpoint is extended as follows: 514 ::= 516 518 [...] 520 Where 522 signal-compatibility-restriction ::= 524 526 The encoding for Optical Interface Class List is described in 527 Section 5.2 of [RWA-Encode]. 529 4.3.1. Signal Processing Exclusion XRO Sub-Object 531 The PCC/PCE should be able to exclude particular types of signal 532 processing along the path in order to handle client restriction or 533 multi-domain path computation. 535 In order to support the exclusion a new XRO sub-object is defined: 536 the signal processing exclusion: 538 0 1 2 3 540 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 1 541 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 542 |X| Type = X | Length | Reserved | Attribute | 543 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 544 | sub-sub objects | 545 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 546 Figure 5 Signaling Processing XRO Sub-Object 548 The Attribute field indicates how the exclusion sub-object is to be 549 interpreted. The Attribute can only be 0 (Interface) or 1 (Node). 551 The sub-sub objects are encoded as in RSVP signaling definition 552 [WSON-Sign]. 554 4.3.2. IRO sub-object: signal processing inclusion 556 Similar to the XRO sub-object the PCC/PCE should be able to include 557 particular types of signal processing along the path in order to 558 handle client restriction or multi-domain path computation. 560 This is supported by adding the sub-object "processing" defined for 561 ERO in [WSON-Sign] to the PCEP IRO object. 563 5. Encoding of a RWA Path Reply 565 The ERO is used to encode the path of a TE LSP through the network. 566 The ERO is carried within a given path of a PCEP response, which is 567 in turn carried in a PCRep message to provide the computed TE LSP if 568 the path computation was successful. The preferred way to convey the 569 allocated wavelength is by means of Explicit Label Control (ELC) 570 [RFC4003]. 572 In order to encode wavelength assignment, the Wavelength Assignment 573 (WA) Object needs to be employed to be able to specify wavelength 574 assignment. Since each segment of the computed optical path is 575 associated with wavelength assignment, the WA Object should be 576 aligned with the ERO object. 578 Encoding details will be provided further revisions and will be 579 aligned as much as possible with [WSON-Sign] and [LSPA-ERO] 581 5.1. Error Indicator 583 To indicate errors associated with the RWA request, a new Error Type 584 (TDB) and subsequent error-values are defined as follows for 585 inclusion in the PCEP-ERROR Object: 587 A new Error-Type (TDB) and subsequent error-values are defined as 588 follows: 590 . Error-Type=TBD; Error-value=1: if a PCE receives a RWA request 591 and the PCE is not capable of processing the request due to 592 insufficient memory, the PCE MUST send a PCErr message with a 593 PCEP-ERROR Object (Error-Type=TDB) and an Error-value(Error- 594 value=1). The PCE stops processing the request. The 595 corresponding RWA request MUST be cancelled at the PCC. 597 . Error-Type=TBD; Error-value=2: if a PCE receives a RWA request 598 and the PCE is not capable of RWA computation, the PCE MUST 599 send a PCErr message with a PCEP-ERROR Object (Error-Type=TDB) 600 and an Error-value (Error-value=2). The PCE stops processing 601 the request. The corresponding RWA computation MUST be 602 cancelled at the PCC. 604 5.2. NO-PATH Indicator 606 To communicate the reason(s) for not being able to find RWA for the 607 path request, the NO-PATH object can be used in the corresponding 608 response. The format of the NO-PATH object body is defined in 609 [RFC5440]. The object may contain a NO-PATH-VECTOR TLV to provide 610 additional information about why a path computation has failed. 612 One new bit flag are defined to be carried in the Flags field in the 613 NO-PATH-VECTOR TLV carried in the NO-PATH Object. 615 . Bit TDB: When set, the PCE indicates no feasible route was 616 found that meets all the constraints (e.g., wavelength 617 restriction, signal compatibility, etc.) associated with RWA. 619 6. Manageability Considerations 621 Manageability of WSON Routing and Wavelength Assignment (RWA) with 622 PCE must address the following considerations: 624 6.1. Control of Function and Policy 626 In addition to the parameters already listed in Section 8.1 of 627 [PCEP], a PCEP implementation SHOULD allow configuring the following 628 PCEP session parameters on a PCC: 630 . The ability to send a WSON RWA request. 632 In addition to the parameters already listed in Section 8.1 of 633 [PCEP], a PCEP implementation SHOULD allow configuring the following 634 PCEP session parameters on a PCE: 636 . The support for WSON RWA. 638 . A set of WSON RWA specific policies (authorized sender, 639 request rate limiter, etc). 641 These parameters may be configured as default parameters for any 642 PCEP session the PCEP speaker participates in, or may apply to a 643 specific session with a given PCEP peer or a specific group of 644 sessions with a specific group of PCEP peers. 646 6.2. Information and Data Models, e.g. MIB module 648 Extensions to the PCEP MIB module defined in [PCEP-MIB] should be 649 defined, so as to cover the WSON RWA information introduced in this 650 document. A future revision of this document will list the 651 information that should be added to the MIB module. 653 6.3. Liveness Detection and Monitoring 655 Mechanisms defined in this document do not imply any new liveness 656 detection and monitoring requirements in addition to those already 657 listed in section 8.3 of [RFC5440]. 659 6.4. Verifying Correct Operation 661 Mechanisms defined in this document do not imply any new 662 verification requirements in addition to those already listed in 663 section 8.4 of [RFC5440] 665 6.5. Requirements on Other Protocols and Functional Components 667 The PCE Discovery mechanisms ([RFC5089] and [RFC5088]) may be used 668 to advertise WSON RWA path computation capabilities to PCCs. 670 6.6. Impact on Network Operation 672 Mechanisms defined in this document do not imply any new network 673 operation requirements in addition to those already listed in 674 section 8.6 of [RFC5440]. 676 7. Security Considerations 678 This document has no requirement for a change to the security models 679 within PCEP [PCEP]. However the additional information distributed 680 in order to address the RWA problem represents a disclosure of 681 network capabilities that an operator may wish to keep private. 682 Consideration should be given to securing this information. 684 8. IANA Considerations 686 A future revision of this document will present requests to IANA for 687 codepoint allocation. 689 9. Acknowledgments 691 The authors would like to thank Adrian Farrel for many helpful 692 comments that greatly improved the contents of this draft. 694 This document was prepared using 2-Word-v2.0.template.dot. 696 10. References 698 10.1. Informative References 700 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 701 Requirement Levels", BCP 14, RFC 2119, March 1997. 703 [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching 704 (GMPLS) Signaling Functional Description", RFC 3471, 705 January 2003. 707 [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label 708 Switching (GMPLS) Signaling Resource ReserVation Protocol- 709 Traffic Engineering (RSVP-TE) Extensions", RFC 3473, 710 January 2003. 712 [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links 713 in Resource ReSerVation Protocol - Traffic Engineering 714 (RSVP-TE)", RFC 3477, January 2003. 716 [RFC4003] Berger, L., "GMPLS Signaling Procedure for Egress Control", 717 RFC 4003, February 2005. 719 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 720 Element (PCE)-Based Architecture", RFC 4655, August 2006. 722 [RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE) 723 Communication Protocol Generic Requirements", RFC 4657, 724 September 2006. 726 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 727 Element (PCE) communication Protocol", RFC 5440, March 728 2009. 730 [PCEP-GMPLS] Margaria, et al., "PCEP extensions for GMPLS", draft- 731 ietf-pce-gmpls-pcep-extensions, work in progress. 733 [LSPA-ERO] Margaria, et al., "LSP Attribute in ERO", draft-margaria- 734 ccamp-lsp-attribute-ero, work in progress. 736 [PCEP-Layer] Oki, Takeda, Le Roux, and Farrel, "Extensions to the 737 Path Computation Element communication Protocol (PCEP) for 738 Inter-Layer MPLS and GMPLS Traffic Engineering", draft- 739 ietf-pce-inter-layer-ext, work in progress. 741 [RFC6163] Lee, Y. and Bernstein, G. (Editors), and W. Imajuku, 742 "Framework for GMPLS and PCE Control of Wavelength 743 Switched Optical Networks", RFC 6163, March 2011. 745 [PCE-RWA] Lee, Y., et. al., "PCEP Requirements for WSON Routing and 746 Wavelength Assignment", draft-ietf-pce-wson-routing- 747 wavelength, work in progress. 749 [RFC6205] Tomohiro, O. and D. Li, "Generalized Labels for Lambda- 750 Switching Capable Label Switching Routers", RFC 6205, 751 January, 2011. 753 [WSON-Sign] Bernstein et al,"Signaling Extensions for Wavelength 754 Switched Optical Networks", draft-ietf-ccamp-wson- 755 signaling, work in progress. 757 [WSON-OSPF] Lee and Bernstein,"OSPF Enhancement for Signal and 758 Network Element Compatibility for Wavelength Switched 759 Optical Networks",draft-ietf-ccamp-wson-signal- 760 compatibility-ospf, work in progress. 762 [RWA-Info] Bernstein and Lee, "Routing and Wavelength Assignment 763 Information Model for Wavelength Switched Optical 764 Networks",draft-ietf-ccamp-rwa-info, work in progress. 766 [RWA-Encode]Bernstein and Lee, "Routing and Wavelength Assignment 767 Information Encoding for Wavelength Switched Optical 768 Networks",draft-ietf-ccamp-rwa-wson-encode, work in 769 progress. 771 [GEN-Encode] Bernstein and Lee, "General Network Element Constraint 772 Encoding for GMPLS Controlled Networks",draft-ietf-ccamp- 773 general-constraint-encode, work in progress. 775 [WSON-Imp] Y. Lee, G. Bernstein, D. Li, G. Martinelli, "A Framework 776 for the Control of Wavelength Switched Optical Networks 777 (WSON) with Impairments", draft-ietf-ccamp-wson- 778 impairments, work in progress. 780 [RSVP-Imp] agraz, "RSVP-TE Extensions in Support of Impairment Aware 781 Routing and Wavelength Assignment in Wavelength Switched 782 Optical Networks WSONs)", draft-agraz-ccamp-wson- 783 impairment-rsvp, work in progress. 785 [OSPF-Imp] Bellagamba, et al., "OSPF Extensions for Wavelength 786 Switched Optical Networks (WSON) with Impairments",draft- 787 eb-ccamp-ospf-wson-impairments, work in progress. 789 11. Contributors 790 Authors' Addresses 792 Young Lee, Editor 793 Huawei Technologies 794 1700 Alma Drive, Suite 100 795 Plano, TX 75075, USA 796 Phone: (972) 509-5599 (x2240) 797 Email: leeyoung@huawei.com 799 Ramon Casellas, Editor 800 CTTC PMT Ed B4 Av. Carl Friedrich Gauss 7 801 08860 Castelldefels (Barcelona) 802 Spain 803 Phone: (34) 936452916 804 Email: ramon.casellas@cttc.es 806 Fatai Zhang 807 Huawei Technologies 808 Email: zhangfatai@huawei.com 810 Cyril Margaria 811 Nokia Siemens Networks 812 St Martin Strasse 76 813 Munich, 81541 814 Germany 815 Phone: +49 89 5159 16934 816 Email: cyril.margaria@nsn.com 818 Oscar Gonzalez de Dios 819 Telefonica Investigacion y Desarrollo 820 C/ Emilio Vargas 6 821 Madrid, 28043 822 Spain 823 Phone: +34 91 3374013 824 Email: ogondio@tid.es 826 Greg Bernstein 827 Grotto Networking 828 Fremont, CA, USA 829 Phone: (510) 573-2237 830 Email: gregb@grotto-networking.com 832 Intellectual Property Statement 833 The IETF Trust takes no position regarding the validity or scope of 834 any Intellectual Property Rights or other rights that might be 835 claimed to pertain to the implementation or use of the technology 836 described in any IETF Document or the extent to which any license 837 under such rights might or might not be available; nor does it 838 represent that it has made any independent effort to identify any 839 such rights. 841 Copies of Intellectual Property disclosures made to the IETF 842 Secretariat and any assurances of licenses to be made available, or 843 the result of an attempt made to obtain a general license or 844 permission for the use of such proprietary rights by implementers or 845 users of this specification can be obtained from the IETF on-line 846 IPR repository at http://www.ietf.org/ipr 848 The IETF invites any interested party to bring to its attention any 849 copyrights, patents or patent applications, or other proprietary 850 rights that may cover technology that may be required to implement 851 any standard or specification contained in an IETF Document. 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