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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: August 2013 CTTC 7 February 6, 2013 9 PCEP Extension for WSON Routing and Wavelength Assignment 11 draft-lee-pce-wson-rwa-ext-05.txt 13 Abstract 15 This draft 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 August 6, 2013. 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 sub-TLV.............................11 70 4.2.2. Wavelength Restriction Field sub-TLV................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..........................................15 76 5.2. NO-PATH Indicator........................................15 77 6. Manageability Considerations..................................16 78 6.1. Control of Function and Policy...........................16 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..............................17 82 6.5. Requirements on Other Protocols and Functional Components17 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...................................................18 88 10.1. Informative References..................................18 89 11. Contributors.................................................20 90 Authors' Addresses...............................................21 91 Intellectual Property Statement..................................21 92 Disclaimer of Validity...........................................22 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 the PCE based Architecture and explains how a Path 108 Computation Element (PCE) may compute Label Switched Paths (LSP) in 109 Multiprotocol Label Switching Traffic Engineering (MPLS-TE) and 110 Generalized MPLS (GMPLS) networks at the request of Path Computation 111 Clients (PCCs). A PCC is said to be any network component that 112 makes such a request and may be, for instance, an Optical Switching 113 Element within a Wavelength Division Multiplexing (WDM) network. 114 The PCE, itself, can be located anywhere within the network, and may 115 be within an optical switching element, a Network Management System 116 (NMS) or Operational Support System (OSS), or may be an independent 117 network server. 119 The PCE communications Protocol (PCEP) is the communication protocol 120 used between PCC and PCE, and may also be used between cooperating 121 PCEs. [RFC4657] sets out the common protocol requirements for PCEP. 122 Additional application-specific requirements for PCEP are deferred 123 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, within a translucent WSON, a LSC LSP may be established 188 between interfaces I1 and I2, spanning 2 transparent segments 189 (optical paths) where the wavelength continuity constraint applies 190 (i.e. the same unique wavelength MUST be assigned to the LSP at each 191 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 constraint 209 as part of RWA path computation. That is, the signal processing 210 capabilities (e.g., modulation and FEC) must be compatible between 211 the sender and the receiver of the optical path across all optical 212 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 Combined Process (R&WA). With this architecture, the 222 two processes of routing and wavelength assignment are accessed via 223 a single PCE. This architecture is the base architecture from which 224 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 The current RP object is used to indicate routing related 241 information in a new path request per [RFC5440]. Since a new RWA 242 path request involves both routing and wavelength assignment, the 243 wavelength assignment related information in the request SHOULD be 244 coupled in the path request. 246 Wavelength allocation can be performed by the PCE by different 247 means: 249 (a) By means of Explicit Label Control, in the sense that one (or 250 two) allocated labels MAY appear after an interface route subobject. 251 (b) By means of a Label Set, containing one or more allocated Labels, 252 provided by the PCE. 254 Option (b) allows distributed label allocation (performed during 255 signaling) to complete wavelength assignment. 257 Additionally, given a range of potential labels to allocate, the 258 request SHOULD convey the heuristic / mechanism to the allocation. 260 The format of a PCReq message after incorporating the WA object is 261 as follows: 263 ::= 265 [] 267 269 Where: 271 ::=[] 273 ::= 275 277 279 [other optional objects...] 281 If WA object is present in the request, the WA object MUST be 282 encoded after the ENDPOINTS object. 284 The format of the Wavelength Assignment (WA) object body is as 285 follows: 287 0 1 2 3 288 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 1 289 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 290 | Flags | O |M| 291 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 292 | | 293 // Optional TLVs // 294 | | 295 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 297 Figure 3 WA Object 299 o Flags (32 bits) 301 The following new flags SHOULD be set 302 M (Mode - 1 bit): M bit is used to indicate the mode of 303 wavelength assignment. When M bit is set to 1, this indicates 304 that the label assigned by the PCE must be explicit. That is, 305 the selected way to convey the allocated wavelength is by means 306 of Explicit Label Control (ELC) [RFC4003] for each hop of a 307 computed LSP. Otherwise, the label assigned by the PCE needs 308 not be explicit (i.e., it can be suggested in the form of label 309 set objects in the corresponding response, to allow distributed 310 WA. In such case, the PCE MUST return a Label Set object as 311 described in Section 2.2 of [Gen-Encode] in the response. 313 O (Order - 3 bits): O bit is used to indicate the wavelength 314 assignment constraint in regard to the order of wavelength 315 assignment to be returned by the PCE. This case is only applied 316 when M bit is set to "explicit." The following indicators 317 should be defined: 319 000 - Reserved 321 001 - Random Assignment 323 010 - First Fit (FF) in descending Order 325 011 - First Fit (FF) in ascending Order 327 100 - Last Fit (LF) in ascending Order 329 101 - Last Fit (LF) in descending Order 331 110 - Unspecified 333 111 - Reserved 335 4.2. Wavelength Restriction Constraint TLV 337 For any request that contains a wavelength assignment, the requester 338 (PCC) MUST be able to specify a restriction on the wavelengths to be 339 used. This restriction is to be interpreted by the PCE as a 340 constraint on the tuning ability of the origination laser 341 transmitter or on any other maintenance related constraints. Note 342 that if the LSP LSC spans different segments, the PCE MUST have 343 mechanisms to know the tunability restrictions of the involved 344 wavelength converters / regenerators, e.g. by means of the TED 345 either via IGP or NMS. Even if the PCE knows the tunability of the 346 transmitter, the PCC MUST be able to apply additional constraints to 347 the request. 349 [Ed note: Which PCEP Object will home this TLV is yet to be 350 determined. Since this involves the end-point, The END-POINTS Object 351 might be a good candidate to encode this TLV, which will be provided 352 in a later revision.] 354 [Ed note: The current encoding assumes that tunability restriction 355 applied to link-level.] 357 The TLV type is TBD, recommended value is TBD. This TLV MAY appear 358 more than once to be able to specify multiple restrictions. 360 The TLV data is defined as follows: 362 ::= 364 366 ( )... 368 Where 370 ::= 372 | | 374 0 1 2 3 375 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 1 376 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 377 | Action | Format | Reserved | 378 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 379 | Link Identifiers | 380 | . . . | 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 382 | Wavelength Restriction Field | 383 // . . . . // 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 Figure 4 Wavelength Restriction 387 o Action: 8 bits 389 0 - Inclusive List indicates that one or more link identifiers 390 are included in the Link Set. Each identifies a separate link 391 that is part of the set. 393 1 - Inclusive Range indicates that the Link Set defines a 394 range of links. It contains two link identifiers. The first 395 identifier indicates the start of the range (inclusive). The 396 second identifier indicates the end of the range (inclusive). 397 All links with numeric values between the bounds are 398 considered to be part of the set. A value of zero in either 399 position indicates that there is no bound on the corresponding 400 portion of the range. Note that the Action field can be set to 401 0 when unnumbered link identifier is used. 403 Note that "interfaces" such as those discussed in the Interfaces MIB 404 [RFC2863] are assumed to be bidirectional. 406 o Format: The format of the link identifier (8 bits) 408 0 -- Unnumbered Link Identifier 409 1 -- Local Interface IPv4 Address 410 2 -- Local Interface IPv6 Address 411 Others TBD. 413 Note that all link identifiers in the same list must be of the same 414 type. 416 o Reserved: Reserved for future use (16 bits) 418 o Link Identifiers: Identifies each link ID for which restriction 419 is applied. The length is dependent on the link format. See the 420 following section for Link Identifier encoding. 422 4.2.1. Link Identifier sub-TLV 424 The link identifier field can be an IPv4, IPv6 or unnumbered 425 interface ID. 427 ::= 429 | | 431 The encoding of each case is as follows: 433 IPv4 prefix Sub-TLV 435 0 1 2 3 436 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 1 437 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 438 | Type = 1 | IPv4 address (4 bytes) | 439 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 440 | IPv4 address (continued) | Prefix Length | Attribute | 441 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 IPv6 prefix Sub-TLV 445 0 1 2 3 446 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 1 447 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 448 | Type = 2 | IPv6 address (16 bytes) | 449 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 450 | IPv6 address (continued) | 451 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 452 | IPv6 address (continued) | 453 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 454 | IPv6 address (continued) | 455 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 456 | IPv6 address (continued) | Prefix Length | Attribute | 457 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 459 Unnumbered Interface ID Sub-TLV 461 0 1 2 3 462 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 1 464 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 465 | Type = 4 | Reserved | Attribute | 466 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 467 | TE Node ID | 468 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 469 | Interface ID | 470 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 472 4.2.2. Wavelength Restriction Field sub-TLV 474 The Wavelength Restriction Field of the wavelength restriction TLV 475 is encoded as a Label Set field as specified in [GEN-Encode] section 476 2.2, as shown below, with base label encoded as a 32 bit LSC label, 477 defined in [RFC6205]. See [RFC6205] for a description of Grid, C.S, 478 Identifier and n, as well as [GEN-Encode] for the details of each 479 action. 481 0 1 2 3 483 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 1 485 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 486 | Action| Num Labels | Length | 487 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 488 |Grid | C.S | Identifier | n | 489 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 490 | Additional fields as necessary per action | 491 | | 492 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 494 4.3. Signal processing capability restrictions 496 Path computation for WSON include the check of signal processing 497 capabilities, those capability MAY be provided by the IGP, however 498 this is not a MUST. Moreover, a PCC should be able to indicate 499 additional restrictions for those signal compatibility, either on 500 the endpoint or any given link. 502 The supported signal processing capabilities are the one described 503 in [RWA-Info]: 505 Optical Interface Class List 506 Bit rate 508 Client signal 510 The Bit-rate restriction is already expressed in [PCEP-GMPLS] in the 511 GENERALIZED-BANDWIDTH object. 513 The client signal information can be expressed using the REQ-ADAP- 514 CAP object from the [PCEP-Layer]. 516 In order to support the Optical Interface Class information a new 517 TLV are introduced as endpoint-restriction in the END-POINTS type 518 Generalized endpoint: 520 Optical Interface Class List TLV 522 The END-POINTS type generalized endpoint is extended as follow: 524 ::= 526 528 [...] 530 Where 532 signal-compatibility-restriction ::= 534 536 The encoding for Optical Interface Class List is described in 537 Section 5.2 of [RWA-Encode]. 539 4.3.1. Signal Processing Exclusion XRO Sub-Object 541 The PCC/PCE should be able to exclude particular types of signal 542 processing along the path in order to handle client restriction or 543 multi-domain path computation. 545 In order to support the exclusion a new XRO sub-object is defined: 546 the signal processing exclusion: 548 0 1 2 3 550 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 1 551 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 552 |X| Type = X | Length | Reserved | Attribute | 553 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 554 | sub-sub objects | 555 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 557 Figure 5 Signaling Processing XRO Sub-Object 559 The Attribute field indicates how the exclusion sub-object is to be 560 interpreted. The Attribute can only be 0 (Interface) or 1 (Node). 562 The sub-sub objects are encoded as in RSVP signaling definition 563 [WSON-Sign]. 565 4.3.2. IRO sub-object: signal processing inclusion 567 Similar to the XRO sub-object the PCC/PCE should be able to include 568 particular types of signal processing along the path in order to 569 handle client restriction or multi-domain path computation. 571 This is supported by adding the sub-object "processing" defined for 572 ERO in [WSON-Sign] to the PCEP IRO object. 574 5. Encoding of a RWA Path Reply 576 The ERO is used to encode the path of a TE LSP through the network. 577 The ERO is carried within a given path of a PCEP response, which is 578 in turn carried in a PCRep message to provide the computed TE LSP if 579 the path computation was successful. The preferred way to convey the 580 allocated wavelength is by means of Explicit Label Control (ELC) 581 [RFC4003]. 583 In order to encode wavelength assignment, the Wavelength Assignment 584 (WA) Object needs to be employed to be able to specify wavelength 585 assignment. Since each segment of the computed optical path is 586 associated with wavelength assignment, the WA Object should be 587 aligned with the ERO object. 589 Encoding details will be provided further revisions and will be 590 aligned as much as possible with [WSON-Sign] and [LSPA-ERO] 592 5.1. Error Indicator 594 To indicate errors associated with the RWA request, a new Error Type 595 (TDB) and subsequent error-values are defined as follows for 596 inclusion in the PCEP-ERROR Object: 598 A new Error-Type (TDB) and subsequent error-values are defined as 599 follows: 601 Error-Type=TBD; Error-value=1: if a PCE receives a RWA request 602 and the PCE is not capable of processing the request due to 603 insufficient memory, the PCE MUST send a PCErr message with a 604 PCEP-ERROR Object (Error-Type=TDB) and an Error-value(Error- 605 value=1). The PCE stops processing the request. The 606 corresponding RWA request MUST be cancelled at the PCC. 608 Error-Type=TBD; Error-value=2: if a PCE receives a RWA request 609 and the PCE is not capable of RWA computation, the PCE MUST 610 send a PCErr message with a PCEP-ERROR Object (Error-Type=15) 611 and an Error-value (Error-value=2). The PCE stops processing 612 the request. The corresponding RWA computation MUST be 613 cancelled at the PCC. 615 5.2. NO-PATH Indicator 617 To communicate the reason(s) for not being able to find RWA for the 618 path request, the NO-PATH object can be used in the PCRep message. 619 The format of the NO-PATH object body is defined in [RFC5440]. The 620 object may contain a NO-PATH-VECTOR TLV to provide additional 621 information about why a path computation has failed. 623 Two new bit flags are defined to be carried in the Flags field in 624 the NO-PATH-VECTOR TLV carried in the NO-PATH Object. 626 Bit TDB: When set, the PCE indicates no feasible route was 627 found that meets all the constraints associated with RWA. 629 Bit TDB: When set, the PCE indicates that no wavelength was 630 assigned to at least one hop of the route in the response. 632 Bit TDB: When set, the PCE indicate that no path was found 633 satisfying the signal compatibility constraints. 635 6. Manageability Considerations 637 Manageability of WSON Routing and Wavelength Assignment (RWA) with 638 PCE must address the following considerations: 640 6.1. Control of Function and Policy 642 In addition to the parameters already listed in Section 8.1 of 643 [PCEP], a PCEP implementation SHOULD allow configuring the following 644 PCEP session parameters on a PCC: 646 The ability to send a WSON RWA request. 648 In addition to the parameters already listed in Section 8.1 of 649 [PCEP], a PCEP implementation SHOULD allow configuring the following 650 PCEP session parameters on a PCE: 652 The support for WSON RWA. 654 A set of WSON RWA specific policies (authorized sender, 655 request rate limiter, etc). 657 These parameters may be configured as default parameters for any 658 PCEP session the PCEP speaker participates in, or may apply to a 659 specific session with a given PCEP peer or a specific group of 660 sessions with a specific group of PCEP peers. 662 6.2. Information and Data Models, e.g. MIB module 664 Extensions to the PCEP MIB module defined in [PCEP-MIB] should be 665 defined, so as to cover the WSON RWA information introduced in this 666 document. A future revision of this document will list the 667 information that should be added to the MIB module. 669 6.3. Liveness Detection and Monitoring 671 Mechanisms defined in this document do not imply any new liveness 672 detection and monitoring requirements in addition to those already 673 listed in section 8.3 of [RFC5440]. 675 6.4. Verifying Correct Operation 677 Mechanisms defined in this document do not imply any new 678 verification requirements in addition to those already listed in 679 section 8.4 of [RFC5440] 681 6.5. Requirements on Other Protocols and Functional Components 683 The PCE Discovery mechanisms ([RFC5089] and [RFC5088]) may be used 684 to advertise WSON RWA path computation capabilities to PCCs. 686 6.6. Impact on Network Operation 688 Mechanisms defined in this document do not imply any new network 689 operation requirements in addition to those already listed in 690 section 8.6 of [RFC5440]. 692 7. Security Considerations 694 This document has no requirement for a change to the security models 695 within PCEP [PCEP]. However the additional information distributed 696 in order to address the RWA problem represents a disclosure of 697 network capabilities that an operator may wish to keep private. 698 Consideration should be given to securing this information. 700 8. IANA Considerations 702 A future revision of this document will present requests to IANA for 703 codepoint allocation. 705 9. Acknowledgments 707 The authors would like to thank Adrian Farrel for many helpful 708 comments that greatly improved the contents of this draft. 710 This document was prepared using 2-Word-v2.0.template.dot. 712 10. References 714 10.1. Informative References 716 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 717 Requirement Levels", BCP 14, RFC 2119, March 1997. 719 [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching 720 (GMPLS) Signaling Functional Description", RFC 3471, 721 January 2003. 723 [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label 724 Switching (GMPLS) Signaling Resource ReserVation Protocol- 725 Traffic Engineering (RSVP-TE) Extensions", RFC 3473, 726 January 2003. 728 [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links 729 in Resource ReSerVation Protocol - Traffic Engineering 730 (RSVP-TE)", RFC 3477, January 2003. 732 [RFC4003] Berger, L., "GMPLS Signaling Procedure for Egress Control", 733 RFC 4003, February 2005. 735 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 736 Element (PCE)-Based Architecture", RFC 4655, August 2006. 738 [RFC4657] Ash, J. and J. Le Roux, "Path Computation Element (PCE) 739 Communication Protocol Generic Requirements", RFC 4657, 740 September 2006. 742 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 743 Element (PCE) communication Protocol", RFC 5440, March 744 2009. 746 [PCEP-GMPLS] Margaria, et al., "PCEP extensions for GMPLS", draft- 747 ietf-pce-gmpls-pcep-extensions, work in progress. 749 [LSPA-ERO] Margaria, et al., "LSP Attribute in ERO", draft-margaria- 750 ccamp-lsp-attribute-ero, work in progress. 752 [PCEP-Layer] Oki, Takeda, Le Roux, and Farrel, "Extensions to the 753 Path Computation Element communication Protocol (PCEP) for 754 Inter-Layer MPLS and GMPLS Traffic Engineering", draft- 755 ietf-pce-inter-layer-ext, work in progress. 757 [RFC6163] Lee, Y. and Bernstein, G. (Editors), and W. Imajuku, 758 "Framework for GMPLS and PCE Control of Wavelength 759 Switched Optical Networks", RFC 6163, March 2011. 761 [PCE-RWA] Lee, Y., et. al., "PCEP Requirements for WSON Routing and 762 Wavelength Assignment", draft-ietf-pce-wson-routing- 763 wavelength, work in progress. 765 [RFC6205] Tomohiro, O. and D. Li, "Generalized Labels for Lambda- 766 Switching Capable Label Switching Routers", RFC 6205, 767 January, 2011. 769 [WSON-Sign] Bernstein et al,"Signaling Extensions for Wavelength 770 Switched Optical Networks", draft-ietf-ccamp-wson- 771 signaling, work in progress. 773 [WSON-OSPF] Lee and Bernstein,"OSPF Enhancement for Signal and 774 Network Element Compatibility for Wavelength Switched 775 Optical Networks",draft-ietf-ccamp-wson-signal- 776 compatibility-ospf, work in progress. 778 [RWA-Info] Bernstein and Lee, "Routing and Wavelength Assignment 779 Information Model for Wavelength Switched Optical 780 Networks",draft-ietf-ccamp-rwa-info, work in progress. 782 [RWA-Encode]Bernstein and Lee, "Routing and Wavelength Assignment 783 Information Encoding for Wavelength Switched Optical 784 Networks",draft-ietf-ccamp-rwa-wson-encode, work in 785 progress. 787 [GEN-Encode] Bernstein and Lee, "General Network Element Constraint 788 Encoding for GMPLS Controlled Networks",draft-ietf-ccamp- 789 general-constraint-encode, work in progress. 791 [WSON-Imp] Y. Lee, G. Bernstein, D. Li, G. Martinelli, "A Framework 792 for the Control of Wavelength Switched Optical Networks 793 (WSON) with Impairments", draft-ietf-ccamp-wson- 794 impairments, work in progress. 796 [RSVP-Imp] agraz, "RSVP-TE Extensions in Support of Impairment Aware 797 Routing and Wavelength Assignment in Wavelength Switched 798 Optical Networks WSONs)", draft-agraz-ccamp-wson- 799 impairment-rsvp, work in progress. 801 [OSPF-Imp] Bellagamba, et al., "OSPF Extensions for Wavelength 802 Switched Optical Networks (WSON) with Impairments",draft- 803 eb-ccamp-ospf-wson-impairments, work in progress. 805 11. Contributors 806 Authors' Addresses 808 Young Lee, Editor 809 Huawei Technologies 810 1700 Alma Drive, Suite 100 811 Plano, TX 75075, USA 812 Phone: (972) 509-5599 (x2240) 813 Email: leeyoung@huawei.com 815 Ramon Casellas, Editor 816 CTTC PMT Ed B4 Av. Carl Friedrich Gauss 7 817 08860 Castelldefels (Barcelona) 818 Spain 819 Phone: (34) 936452916 820 Email: ramon.casellas@cttc.es 822 Fatai Zhang 823 Huawei Technologies 824 Email: zhangfatai@huawei.com 826 Cyril Margaria 827 Nokia Siemens Networks 828 St Martin Strasse 76 829 Munich, 81541 830 Germany 831 Phone: +49 89 5159 16934 832 Email: cyril.margaria@nsn.com 834 Oscar Gonzalez de Dios 835 Telefonica Investigacion y Desarrollo 836 C/ Emilio Vargas 6 837 Madrid, 28043 838 Spain 839 Phone: +34 91 3374013 840 Email: ogondio@tid.es 842 Greg Bernstein 843 Grotto Networking 844 Fremont, CA, USA 845 Phone: (510) 573-2237 846 Email: gregb@grotto-networking.com 848 Intellectual Property Statement 849 The IETF Trust takes no position regarding the validity or scope of 850 any Intellectual Property Rights or other rights that might be 851 claimed to pertain to the implementation or use of the technology 852 described in any IETF Document or the extent to which any license 853 under such rights might or might not be available; nor does it 854 represent that it has made any independent effort to identify any 855 such rights. 857 Copies of Intellectual Property disclosures made to the IETF 858 Secretariat and any assurances of licenses to be made available, or 859 the result of an attempt made to obtain a general license or 860 permission for the use of such proprietary rights by implementers or 861 users of this specification can be obtained from the IETF on-line 862 IPR repository at http://www.ietf.org/ipr 864 The IETF invites any interested party to bring to its attention any 865 copyrights, patents or patent applications, or other proprietary 866 rights that may cover technology that may be required to implement 867 any standard or specification contained in an IETF Document. 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