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'G.800' -- Possible downref: Non-RFC (?) normative reference: ref. 'G.805' -- Possible downref: Non-RFC (?) normative reference: ref. 'G.8080' -- Possible downref: Non-RFC (?) normative reference: ref. 'G.870' -- Possible downref: Non-RFC (?) normative reference: ref. 'G.872' -- Possible downref: Non-RFC (?) normative reference: ref. 'G.959.1-2013' ** Downref: Normative reference to an Informational RFC: RFC 6163 Summary: 3 errors (**), 0 flaws (~~), 6 warnings (==), 10 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group O. Gonzalez de Dios, Ed. 3 Internet-Draft Telefonica I+D 4 Intended status: Standards Track R. Casellas, Ed. 5 Expires: August 18, 2014 CTTC 6 F. Zhang 7 Huawei 8 X. Fu 9 ZTE 10 D. Ceccarelli 11 Ericsson 12 I. Hussain 13 Infinera 14 February 14, 2014 16 Framework and Requirements for GMPLS based control of Flexi-grid DWDM 17 networks 18 draft-ietf-ccamp-flexi-grid-fwk-01 20 Abstract 22 This document defines a framework and the associated control plane 23 requirements for the GMPLS based control of flexi-grid DWDM networks. 24 To allow efficient allocation of optical spectral bandwidth for high 25 bit-rate systems, the International Telecommunication Union 26 Telecommunication Standardization Sector (ITU-T) has extended the 27 recommendations [G.694.1] and [G.872] to include the concept of 28 flexible grid. A new DWDM grid has been developed within the ITU-T 29 Study Group 15 by defining a set of nominal central frequencies, 30 channel spacings and the concept of "frequency slot". In such 31 environment, a data plane connection is switched based on allocated, 32 variable-sized frequency ranges within the optical spectrum. 34 Status of This Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at http://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on August 18, 2014. 50 Copyright Notice 52 Copyright (c) 2014 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 68 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 69 3. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . 4 70 4. Flexi-grid Networks . . . . . . . . . . . . . . . . . . . . . 4 71 4.1. Flexi-grid in the context of OTN . . . . . . . . . . . . 4 72 4.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 73 4.2.1. Frequency Slots . . . . . . . . . . . . . . . . . . . 5 74 4.2.2. Media Channels . . . . . . . . . . . . . . . . . . . 7 75 4.2.3. Media Layer Elements . . . . . . . . . . . . . . . . 7 76 4.2.4. Optical Tributary Signals . . . . . . . . . . . . . . 8 77 4.3. Flexi-grid layered network model . . . . . . . . . . . . 8 78 4.3.1. Hierarchy in the Media Layer . . . . . . . . . . . . 9 79 4.3.2. DWDM flexi-grid enabled network element models . . . 10 80 5. GMPLS applicability . . . . . . . . . . . . . . . . . . . . . 11 81 5.1. General considerations . . . . . . . . . . . . . . . . . 11 82 5.2. Considerations on TE Links . . . . . . . . . . . . . . . 11 83 5.3. Considerations on Labeled Switched Path (LSP) in Flexi- 84 grid . . . . . . . . . . . . . . . . . . . . . . . . . . 14 85 5.4. Control Plane modeling of Network elements . . . . . . . 18 86 5.5. Media Layer Resource Allocation considerations . . . . . 19 87 5.6. Neighbor Discovery and Link Property Correlation . . . . 23 88 5.7. Path Computation / Routing and Spectrum Assignment (RSA) 23 89 5.7.1. Architectural Approaches to RSA . . . . . . . . . . . 24 90 5.8. Routing / Topology dissemination . . . . . . . . . . . . 24 91 5.8.1. Available Frequency Ranges/slots of DWDM Links . . . 25 92 5.8.2. Available Slot Width Ranges of DWDM Links . . . . . . 25 93 5.8.3. Spectrum Management . . . . . . . . . . . . . . . . . 25 94 5.8.4. Information Model . . . . . . . . . . . . . . . . . . 26 95 6. Control Plane Requirements . . . . . . . . . . . . . . . . . 27 96 6.1. Support for Media Channels . . . . . . . . . . . . . . . 27 97 6.2. Support for Media Channel Resizing . . . . . . . . . . . 27 98 6.3. Support for Logical Associations of multiple media 99 channels . . . . . . . . . . . . . . . . . . . . . . . . 28 100 7. Security Considerations . . . . . . . . . . . . . . . . . . . 28 101 8. Contributing Authors . . . . . . . . . . . . . . . . . . . . 28 102 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30 103 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 104 10.1. Normative References . . . . . . . . . . . . . . . . . . 30 105 10.2. Informative References . . . . . . . . . . . . . . . . . 32 106 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 108 1. Requirements Language 110 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 111 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 112 document are to be interpreted as described in [RFC2119]. 114 2. Introduction 116 The term "Flexible grid" (flexi-grid for short) as defined by the 117 International Telecommunication Union Telecommunication 118 Standardization Sector (ITU-T) Study Group 15 in the latest version 119 of [G.694.1], refers to the updated set of nominal central 120 frequencies (a frequency grid), channel spacing and optical spectrum 121 management/allocation considerations that have been defined in order 122 to allow an efficient and flexible allocation and configuration of 123 optical spectral bandwidth for high bit-rate systems. 125 A key concept of flexi-grid is the "frequency slot"; a variable-sized 126 optical frequency range that can be allocated to a data connection. 127 As detailed later in the document, a frequency slot is characterized 128 by its nominal central frequency and its slot width which, as per 129 [G.694.1], is constrained to be a multiple of a given slot width 130 granularity. 132 Compared to a traditional fixed grid network, which uses fixed size 133 optical spectrum frequency ranges or "frequency slots" with typical 134 channel separations of 50 GHz, a flexible grid network can select its 135 media channels with a more flexible choice of slot widths, allocating 136 as much optical spectrum as required, allowing high bit rate signals 137 (e.g., 400G, 1T or higher) that do not fit in the fixed grid. 139 From a networking perspective, a flexible grid network is assumed to 140 be a layered network [G.872][G.800] in which the media layer is the 141 server layer and the optical signal layer is the client layer. In 142 the media layer, switching is based on a frequency slot, and the size 143 of a media channel is given by the properties of the associated 144 frequency slot. In this layered network, the media channel 145 transports an Optical Tributary Signal. 147 A Wavelength Switched Optical Network (WSON), addressed in [RFC6163], 148 is a term commonly used to refer to the application/deployment of a 149 Generalized Multi-Protocol Label Switching (GMPLS)-based control 150 plane for the control (provisioning/recovery, etc) of a fixed grid 151 WDM network in which media (spectrum) and signal are jointly 152 considered 154 This document defines the framework for a GMPLS-based control of 155 flexi-grid enabled DWDM networks (in the scope defined by ITU-T 156 layered Optical Transport Networks [G.872]), as well as a set of 157 associated control plane requirements. An important design 158 consideration relates to the decoupling of the management of the 159 optical spectrum resource and the client signals to be transported. 161 3. Acronyms 163 EFS: Effective Frequency Slot 165 FS: Frequency Slot 167 NCF: Nominal Central Frequency 169 OCh: Optical Channel 171 OCh-P: Optical Channel Payload 173 OTS: Optical Tributary Signal 175 OCC: Optical Channel Carrier 177 SWG: Slot Width Granularity 179 4. Flexi-grid Networks 181 4.1. Flexi-grid in the context of OTN 183 [G.872] describes from a network level the functional architecture of 184 Optical Transport Networks (OTN). The OTN is decomposed into 185 independent layer networks with client/layer relationships among 186 them. A simplified view of the OTN layers is shown in Figure 1. 188 +----------------+ 189 | Digital Layer | 190 +----------------+ 191 | Signal Layer | 192 +----------------+ 193 | Media Layer | 194 +----------------+ 196 Figure 1: Generic OTN overview 198 In the OTN layering context, the media layer is the server layer of 199 the optical signal layer. The optical signal is guided to its 200 destination by the media layer by means of a network media channel. 201 In the media layer, switching is based on a frequency slot, and the 202 size of a media channel is given by the properties of the associated 203 frequency slot. 205 In this scope, this document uses the term flexi-grid enabled DWDM 206 network to refer to a network in which switching is based on 207 frequency slots defined using the flexible grid, and covers mainly 208 the Media Layer as well as the required adaptations from the Signal 209 layer. The present document is thus focused on the control and 210 management of the media layer. 212 4.2. Terminology 214 This section presents the definition of the terms used in flexi-grid 215 networks. These terms are included in the ITU-T recommendations 216 [G.694.1], [G.872]), [G.870], [G.8080] and [G.959.1-2013]. 218 Where appropriate, this documents also uses terminology and 219 lexicography from [RFC4397]. 221 4.2.1. Frequency Slots 223 This subsection is focused on the frequency slot related terms. 225 o Frequency Slot [G.694.1]: The frequency range allocated to a slot 226 within the flexible grid and unavailable to other slots. A 227 frequency slot is defined by its nominal central frequency and its 228 slot width. 230 Nominal Central Frequency: each of the allowed frequencies as per the 231 definition of flexible DWDM grid in [G.694.1]. The set of nominal 232 central frequencies can be built using the following expression f = 233 193.1 THz + n x 0.00625 THz, where 193.1 THz is ITU-T ''anchor 234 frequency'' for transmission over the C band, n is a positive or 235 negative integer including 0. 237 -5 -4 -3 -2 -1 0 1 2 3 4 5 <- values of n 238 ...+--+--+--+--+--+--+--+--+--+--+- 239 ^ 240 193.1 THz <- anchor frequency 242 Figure 2: Anchor frequency and set of nominal central frequencies 244 Nominal Central Frequency Granularity: It is the spacing between 245 allowed nominal central frequencies and it is set to 6.25 GHz (note: 246 sometimes referred to as 0.00625 THz). 248 Slot Width Granularity: 12.5 GHz, as defined in [G.694.1]. 250 Slot Width: The slot width determines the "amount" of optical 251 spectrum regardless of its actual "position" in the frequency axis. 252 A slot width is constrained to be m x SWG (that is, m x 12.5 GHz), 253 where m is an integer greater than or equal to 1. 255 Frequency Slot 1 Frequency Slot 2 256 ------------- ------------------- 257 | | | | 258 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 259 ..--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... 260 ------------- ------------------- 261 ^ ^ 262 Central F = 193.1THz Central F = 193.14375 THz 263 Slot width = 25 GHz Slot width = 37.5 GHz 265 Figure 3: Example Frequency slots 267 o The symbol '+' represents the allowed nominal central frequencies, 268 the '--' represents the nominal central frequency granularity, and 269 the '^' represents the slot nominal central frequency. The number 270 on the top of the '+' symbol represents the 'n' in the frequency 271 calculation formula. The nominal central frequency is 193.1 THz 272 when n equals zero. 274 Effective Frequency Slot: the effective frequency slot of a media 275 channel is the common part of the frequency slots along the media 276 channel through a particular path through the optical network. It is 277 a logical construct derived from the (intersection of) frequency 278 slots allocated to each device in the path. The effective frequency 279 slot is an attribute of a media channel and, being a frequency slot, 280 it is described by its nominal central frequency and slot width, 281 according to the already described rules. 283 Frequency Slot 1 284 ------------- 285 | | 286 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 287 ..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--... 289 Frequency Slot 2 290 ------------------- 291 | | 292 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 293 ..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--... 295 =============================================== 296 Effective Frequency Slot 297 ------------- 298 | | 299 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 300 ..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--... 302 Figure 4: Effective Frequency Slot 304 4.2.2. Media Channels 306 Media Channel: a media association that represents both the topology 307 (i.e., path through the media) and the resource (frequency slot) that 308 it occupies. As a topological construct, it represents a (effective) 309 frequency slot supported by a concatenation of media elements 310 (fibers, amplifiers, filters, switching matrices...). This term is 311 used to identify the end-to-end physical layer entity with its 312 corresponding (one or more) frequency slots local at each link 313 filters. 315 Network Media Channel: It is a media channel that transports an 316 Optical Tributary Signal [Editor's note: this definition goes beyond 317 current G.870 definition, which is still tightened to a particular 318 case of OTS, the OCh-P] 320 4.2.3. Media Layer Elements 322 Media Element: a media element only directs the optical signal or 323 affects the properties of an optical signal, it does not modify the 324 properties of the information that has been modulated to produce the 325 optical signal [G.870]. Examples of media elements include fibers, 326 amplifiers, filters and switching matrices. 328 Media Channel Matrixes: the media channel matrix provides flexible 329 connectivity for the media channels. That is, it represents a point 330 of flexibility where relationships between the media ports at the 331 edge of a media channel matrix may be created and broken. The 332 relationship between these ports is called a matrix channel. 333 (Network) Media Channels are switched in a Media Channel Matrix. 335 4.2.4. Optical Tributary Signals 337 Optical Tributary Signal [G.959.1-2013]: The optical signal that is 338 placed within a network media channel for transport across the 339 optical network. This may consist of a single modulated optical 340 carrier or a group of modulated optical carriers or subcarriers. One 341 particular example of Optical Tributary Signal is an Optical Channel 342 Payload (OCh-P) [G.872]. 344 4.3. Flexi-grid layered network model 346 In the OTN layered network, the network media channel transports a 347 single Optical Tributary Signal (see Figure 5) 349 | Optical Tributary Signal | 350 O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O 351 | | 352 | Channel Port Network Media Channel Channel Port | 353 O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O 354 | | 355 +--------+ +-----------+ +--------+ 356 | \ (1) | | (1) | | (1) / | 357 | \----|-----------------|-----------|-------------------|-----/ | 358 +--------+ Link Channel +-----------+ Link Channel +--------+ 359 Media Channel Media Channel Media Channel 360 Matrix Matrix Matrix 362 (1) - Matrix Channel 364 Figure 5: Simplified Layered Network Model 366 A particular example of Optical Tributary Signal is the OCh-P. 367 Figure Figure 6 shows the example of the layered network model 368 particularized for the OCH-P case, as defined in G.805. 370 OCh AP Trail (OCh) OCh AP 371 O- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O 372 | | 373 --- OCh-P OCh-P --- 374 \ / source sink \ / 375 + + 376 | OCh-P OCh-P Network Connection OCh-P | 377 O TCP - - - - - - - - - - - - - - - - - - - - - - - - - - -TCP O 378 | | 379 |Channel Port Network Media Channel Channel Port | 380 O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O 381 | | 382 +--------+ +-----------+ +---------+ 383 | \ (1) | OCh-P LC | (1) | OCh-P LC | (1) / | 384 | \----|-----------------|-----------|-----------------|------/ | 385 +--------+ Link Channel +-----------+ Link Channel +---------+ 386 Media Channel Media Channel Media Channel 387 Matrix Matrix Matrix 389 (1) - Matrix Channel 391 Figure 6: Layered Network Model according to G.805 393 By definition a network media channel only supports a single Optical 394 Tributary signal. How several Optical Tributary signals are bound 395 together is out of the scope of the present document and is a matter 396 of the signal layer. 398 4.3.1. Hierarchy in the Media Layer 400 In summary, the concept of frequency slot is a logical abstraction 401 that represents a frequency range while the media layer represents 402 the underlying media support. Media Channels are media associations, 403 characterized by their (effective) frequency slot, respectively; and 404 media channels are switched in media channel matrixes. From the 405 control and management perspective, a media channel can be logically 406 splited in other media channels. 408 In Figure 7 , a Media Channel has been configured and dimensioned to 409 support two network media channels, each of them carrying one optical 410 tributary signal. 412 Media Channel Frequency Slot 413 +-------------------------------X------------------------------+ 414 | | 415 | Frequency Slot Frequency Slot | 416 | +------------X-----------+ +----------X-----------+ | 417 | | Opt Tributary Signal | | Opt Tributary Signal | | 418 | | o | | o | | 419 | | | | | | | | 420 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 421 +---+---+---+---+---+---+---+---+---+---+---+--+---+---+---+---+--- 423 <- Network Media Channel-> <- Network Media Channel-> 425 <------------------------ Media Channel -----------------------> 427 X - Frequency Slot Central Frequency 429 o - signal central frequency 431 Figure 7: Example of Media Channel / Network Media Channels and 432 associated frequency slots 434 4.3.2. DWDM flexi-grid enabled network element models 436 Similar to fixed grid networks, a flexible grid network is also 437 constructed from subsystems that include Wavelength Division 438 Multiplexing (WDM) links, tunable transmitters and receivers, i.e, 439 media elements including media layer switching elements (media 440 matrices), as well as electro-optical network elements, all of them 441 with flexible grid characteristics. 443 As stated in [G.694.1] the flexible DWDM grid defined in Clause 7 has 444 a nominal central frequency granularity of 6.25 GHz and a slot width 445 granularity of 12.5 GHz. However, devices or applications that make 446 use of the flexible grid may not be capable of supporting every 447 possible slot width or position. In other words, applications may be 448 defined where only a subset of the possible slot widths and positions 449 are required to be supported. For example, an application could be 450 defined where the nominal central frequency granularity is 12.5 GHz 451 (by only requiring values of n that are even) and that only requires 452 slot widths as a multiple of 25 GHz (by only requiring values of m 453 that are even). 455 5. GMPLS applicability 457 The goal of this section is to provide an insight of the application 458 of GMPLS to control flexi-grid networks, while specific requirements 459 are covered in the next section. The present framework is aimed at 460 controlling the media layer within the Optical Transport Network 461 (OTN) hierarchy and the required adaptations of the signal layer. 462 This document also defines the term SSON (Spectrum-Switched Optical 463 Network) to refer to a Flexi-grid enabled DWDM network that is 464 controlled by a GMPLS/PCE control plane. 466 This section provides a mapping of the ITU-T G.872 architectural 467 aspects to GMPLS/Control plane terms, and considers the relationship 468 between the architectural concept/construct of media channel and its 469 control plane representations (e.g. as a TE link). 471 5.1. General considerations 473 The GMPLS control of the media layer deals with the establishment of 474 media channels, which are switched in media channel matrixes. GMPLS 475 labels locally represent the media channel and its associated 476 frequency slot. Network media channels are considered a particular 477 case of media channels when the end points are transceivers (that is, 478 source and destination of an Optical Tributary Signal) 480 5.2. Considerations on TE Links 482 From a theoretical / abstract point of view, a fiber can be modeled 483 has having a frequency slot that ranges from (-inf, +inf). This 484 representation helps understand the relationship between frequency 485 slots / ranges. 487 The frequency slot is a local concept that applies locally to a 488 component / element. When applied to a media channel, we are 489 referring to its effective frequency slot as defined in [G.872]. 491 The association of a filter, a fiber and a filter is a media channel 492 in its most basic form, which from the control plane perspective may 493 modeled as a (physical) TE-link with a contiguous optical spectrum at 494 start of day. A means to represent this is that the portion of 495 spectrum available at time t0 depends on which filters are placed at 496 the ends of the fiber and how they have been configured. Once 497 filters are placed we have the one hop media channel. In practical 498 terms, associating a fiber with the terminating filters determines 499 the usable optical spectrum. 501 -----------------+ +-----------------+ 502 | | 503 +--------+ +--------+ 504 | | | | +--------- 505 ---o| =============================== o--| 506 | | Fiber | | | --\ /-- 507 ---o| | | o--| \/ 508 | | | | | /\ 509 ---o| =============================== o--| --/ \-- 510 | Filter | | Filter | | 511 | | | | +--------- 512 +--------+ +--------+ 513 | | 514 |------- Basic Media Channel ---------| 515 -----------------+ +-----------------+ 517 --------+ +-------- 518 |--------------------------------------| 519 LSR | TE link | LSR 520 |--------------------------------------| 521 +--------+ +-------- 523 Figure 8: (Basic) Media channel and TE link 525 Additionally, when a cross-connect for a specific frequency slot is 526 considered, the underlying media support is still a media channel, 527 augmented, so to speak, with a bigger association of media elements 528 and a resulting effective slot. When this media channel is the 529 result of the association of basic media channels and media layer 530 matrix cross-connects, this architectural construct can be 531 represented as / corresponds to a Label Switched Path (LSP) from a 532 control plane perspective. In other words, It is possible to 533 "concatenate" several media channels (e.g. Patch on intermediate 534 nodes) to create a single media channel. 536 -----------+ +------------------------------+ +---------- 537 | | | | 538 +------+ +------+ +------+ +------+ 539 | | | | +----------+ | | | | 540 --o| ========= o--| |--o ========= o-- 541 | | Fiber | | | --\ /-- | | | Fiber | | 542 --o| | | o--| \/ |--o | | o-- 543 | | | | | /\ | | | | | 544 --o| ========= o--***********|--o ========= o-- 545 |Filter| |Filter| | | |Filter| |Filter| 546 | | | | | | | | 547 +------+ +------+ +------+ +------+ 548 | | | | 549 <- Basic Media -> <- Matrix -> <- Basic Media-> 550 |Channel| Channel |Channel| 551 -----------+ +------------------------------+ +---------- 553 <-------------------- Media Channel ----------------> 555 -----+ +---------------+ +------- 556 |------------------| |------------------| 557 LSR | TE link | LSR | TE link | LSR 558 |------------------| |------------------| 559 -----+ +---------------+ +------- 561 Figure 9: Extended Media Channel 563 Additionally, if appropriate, it can also be represented as a TE link 564 or Forwarding Adjacency (FA), augmenting the control plane network 565 model. 567 -----------+ +------------------------------+ +---------- 568 | | | | 569 +------+ +------+ +------+ +------+ 570 | | | | +----------+ | | | | 571 --o| ========= o--| |--o ========= o-- 572 | | Fiber | | | --\ /-- | | | Fiber | | 573 --o| | | o--| \/ |--o | | o-- 574 | | | | | /\ | | | | | 575 --o| ========= o--***********|--o ========= o-- 576 |Filter| |Filter| | | |Filter| |Filter| 577 | | | | | | | | 578 +------+ +------+ +------+ +------+ 579 | | | | 580 -----------+ +------------------------------+ +---------- 582 <------------------------ Media Channel -----------> 584 +-----+ +------ 585 |------------------------------------------------------| 586 LSR | TE link | LSR 587 |------------------------------------------------------| 588 +-----+ +------ 590 Figure 10: Extended Media Channel / TE Link / FA 592 5.3. Considerations on Labeled Switched Path (LSP) in Flexi-grid 594 The flexi-grid LSP is seen as a control plane representation of a 595 media channel. Since network media channels are media channels, an 596 LSP may also be the control plane representation of a network media 597 channel, in a particular context. From a control plane perspective, 598 the main difference (regardless of the actual effective frequency 599 slot which may be dimensioned arbitrarily) is that the LSP that 600 represents a network media channel also includes the endpoints 601 (transceivers) , including the cross-connects at the ingress / egress 602 nodes. The ports towards the client can still be represented as 603 interfaces from the control plane perspective. 605 Figure 11 describes an LSP routed along 3 nodes. The LSP is 606 terminated before the optical matrix of the ingress and egress nodes 607 and can represent a Media Channel. This case does NOT (and cannot) 608 represent a network media channel as it does not include (and cannot 609 include) the transceivers. 611 ----------+ +--------------------------------+ +--------- 612 | | | | 613 +------+ +------+ +------+ +------+ 614 | | | | +----------+ | | | | 615 -o| ========= o---| |---o ========= o- 616 | | Fiber | | | --\ /-- | | | Fiber | | 617 -o|>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>o- 618 | | | | | /\ | | | | | 619 -o| ========= o---***********|---o ========= o- 620 |Filter| |Filter| | | |Filter| |Filter| 621 | | | | | | | | 622 +------+ +------+ +------+ +------+ 623 | | | | 624 ----------+ +--------------------------------+ +--------- 626 >>>>>>>>>>>>>>>>>>>>>>>>>>>> LSP >>>>>>>>>>>>>>>>>>>>>>>> 627 -----+ +---------------+ +----- 628 |------------------| |----------------| 629 LSR | TE link | LSR | TE link | LSR 630 |------------------| |----------------| 631 -----+ +---------------+ +----- 633 Figure 11: Flex-grid LSP representing a media channel that starts at 634 the filter of the outgoing interface of the ingress LSR and ends at 635 the filter of the incoming interface of the egress LSR 637 In Figure 12 a Network Media Channel is represented as terminated at 638 the DWDM side of the transponder, this is commonly named as OCh-trail 639 connection. 641 |--------------------- Network Media Channel ----------------------| 643 +----------------------+ +----------------------+ 644 | | | 645 +------+ +------+ +------+ +------+ 646 | | +----+ | | | | +----+ | |OCh-P 647 OCh-P| o-| |-o | +-----+ | o-| |-o |sink 648 src | | | | | ===+-+ +-+==| | | | | O---|R 649 T|***o******o******************************************************** 650 | | |\ /| | | | | | | | |\ /| | | 651 | o-| \/ |-o ===| | | |==| o-| \/ |-o | 652 | | | /\ | | | +-+ +-+ | | | /\ | | | 653 | o-|/ \|-o | | \/ | | o-|/ \|-o | 654 |Filter| | | |Filter| | /\ | |Filter| | | |Filter| 655 +------+ | | +------+ +-----+ +------+ | | +------+ 656 | | | | | | | | 657 +----------------------+ +----------------------+ 658 LSP 659 <-------------------------------------------------------------------> 661 LSP 662 <------------------------------------------------------------------> 663 +-----+ +--------+ +-----+ 664 o--- | |-------------------| |----------------| |---o 665 | LSR | TE link | LSR | TE link | LSR | 666 | |-------------------| |----------------| | 667 +-----+ +--------+ +-----+ 669 Figure 12: LSP representing a network media channel (OCh-Trail) 671 In a third case, a Network Media Channel terminated on the Filter 672 ports of the Ingress and Egress nodes. This is named in G.872 as 673 OCh-NC (we need to discuss the implications, if any, once modeled at 674 the control plane level of models B and C). 676 |--------------------- Network Media Channel --------------------| 678 +------------------------+ +------------------------+ 679 +------+ +------+ +------+ +------+ 680 | | +----+ | | | | +----+ | | 681 | o-| |-o | +------+ | o-| |-o | 682 | | | | | =====+-+ +-+=====| | | | | | 683 T-o******o********************************************************O-R 684 | | |\ /| | | | | | | | |\ /| | | 685 | o-| \/ |-o =====| | | |=====| o-| \/ |-o | 686 | | | /\ | | | +-+ +-+ | | | /\ | | | 687 | o-|/ \|-o | | \/ | | o-|/ \|-o | 688 |Filter| | | |Filter| | /\ | |Filter| | | |Filter| 689 +------+ | | +------+ +------+ +------+ | | +------+ 690 | | | | | | | | 691 +----------------------+ +----------------------+ 692 <-----------------------------------------------------------------> 693 LSP 695 LSP 696 <--------------------------------------------------------------> 697 +-----+ +--------+ +-----+ 698 o--| |--------------------| |-------------------| |--o 699 | LSR | TE link | LSR | TE link | LSR | 700 | |--------------------| |-------------------| | 701 +-----+ +--------+ +-----+ 703 Figure 13: LSP representing a network media channel (OCh-P NC) 705 [Note: not clear the difference, from a control plane perspective, of 706 figs Figure 12 and Figure 13.] 708 Applying the notion of hierarchy at the media layer, by using the LSP 709 as a FA, the media channel created can support multiple (sub) media 710 channels. [Editot note : a specific behavior related to Hierarchies 711 will be verified at a later point in time]. 713 +--------------+ +--------------+ 714 | OCh-P | TE | OCh-P | Virtual TE 715 | | link | | link 716 | Matrix |o- - - - - - - - - - o| Matrix |o- - - - - - 717 +--------------+ +--------------+ 718 | +---------+ | 719 | | Media | | 720 |o----| Channel |-----o| 721 | | 722 | Matrix | 723 +---------+ 725 Figure 14: MRN/MLN topology view with TE link / FA 727 Note that there is only one media layer switch matrix (one 728 implementation is FlexGrid ROADM) in SSON, while "signal layer LSP is 729 mainly for the purpose of management and control of individual 730 optical signal". Signal layer LSPs (OChs) with the same attributions 731 (such as source and destination) could be grouped into one media- 732 layer LSP (media channel), which has advantages in spectral 733 efficiency (reduce guard band between adjacent OChs in one FSC) and 734 LSP management. However, assuming some network elements indeed 735 perform signal layer switch in SSON, there must be enough guard band 736 between adjacent OChs in one media channel, in order to compensate 737 filter concatenation effect and other effects caused by signal layer 738 switching elements. In such condition, the separation of signal 739 layer from media layer cannot bring any benefit in spectral 740 efficiency and in other aspects, but make the network switch and 741 control more complex. If two OChs must switch to different ports, it 742 is better to carry them by diferent FSCs and the media layer switch 743 is enough in this scenario. 745 5.4. Control Plane modeling of Network elements 747 Optical transmitters/receivers may have different tunability 748 constraints, and media channel matrixes may have switching 749 restrictions. Additionally, a key feature of their implementation is 750 their highly asymmetric switching capability which is described in 751 [RFC6163] in detail. Media matrices include line side ports which 752 are connected to DWDM links and tributary side input/output ports 753 which can be connected to transmitters/receivers. 755 A set of common constraints can be defined: 757 o The minimum and maximum slot width. 759 o Granularity: the optical hardware may not be able to select 760 parameters with the lowest granularity (e.g. 6.25 GHz for nominal 761 central frequencies or 12.5 GHz for slot width granularity). 763 o Available frequency ranges: the set or union of frequency ranges 764 that are not allocated (i.e. available). The relative grouping 765 and distribution of available frequency ranges in a fiber is 766 usually referred to as ''fragmentation''. 768 o Available slot width ranges: the set or union of slot width ranges 769 supported by media matrices. It includes the following 770 information. 772 * Slot width threshold: the minimum and maximum Slot Width 773 supported by the media matrix. For example, the slot width can 774 be from 50GHz to 200GHz. 776 * Step granularity: the minimum step by which the optical filter 777 bandwidth of the media matrix can be increased or decreased. 778 This parameter is typically equal to slot width granularity 779 (i.e. 12.5GHz) or integer multiples of 12.5GHz. 781 [Editor's note: different configurations such as C/CD/CDC will be 782 added later. This section should state specifics to media channel 783 matrices, ROADM models need to be moved to an appendix]. 785 5.5. Media Layer Resource Allocation considerations 787 A media channel has an associated effective frequency slot. From the 788 perspective of network control and management, this effective slot is 789 seen as the "usable" frequency slot end to end. The establishment of 790 an LSP related the establishment of the media channel and effective 791 frequency slot. 793 In this context, when used unqualified, the frequency slot is a local 794 term, which applies at each hop. An effective frequency slot applies 795 at the media chall (LSP) level 797 A "service" request is characterized as a minimum, by its required 798 effective slot width. This does not preclude that the request may 799 add additional constraints such as imposing also the nominal central 800 frequency. A given frequency slot is requested for the media channel 801 say, with the Path message. Regardless of the actual encoding, the 802 Path message sender descriptor sender_tspec shall specify a minimum 803 frequency slot width that needs to be fulfilled. 805 In order to allocate a proper effective frequency slot for a LSP, the 806 signaling should specify its required slot width. 808 An effective frequency slot must equally be described in terms of a 809 central nominal frequency and its slot width (in terms of usable 810 spectrum of the effective frequency slot). That is, one must be able 811 to obtain an end-to-end equivalent n and m parameters. We refer to 812 this as the "effective frequency slot of the media channel/LSP must 813 be valid". 815 In GMPLS the requested effective frequency slot is represented to the 816 TSpec and the effective frequency slot is mapped to the FlowSpec. 818 The switched element corresponds in GMPLS to the 'label'. As in 819 flexi-grid the switched element is a frequency slot, the label 820 represents a frequency slot. Consequently, the label in flexi-grid 821 must convey the necessary information to obtain the frequency slot 822 characteristics (i.e, center and width, the n and m parameters). The 823 frequency slot is locally identified by the label 825 The local frequency slot may change at each hop, typically given 826 hardware constraints (e.g. a given node cannot support the finest 827 granularity). Locally n and m may change. As long as a given 828 downstream node allocates enough optical spectrum, m can be different 829 along the path. This covers the issue where concrete media matrices 830 can have different slot width granularities. Such "local" m will 831 appear in the allocated label that encodes the frequency slot as well 832 as the flow descriptor flowspec. 834 Different modes are considered: RSA with explicit label control, and 835 for R+DSA, the GMPLS signaling procedure is similar to the one 836 described in section 4.1.3 of [RFC6163] except that the label set 837 should specify the available nominal central frequencies that meet 838 the slot width requirement of the LSP. The intermediate nodes can 839 collect the acceptable central frequencies that meet the slot width 840 requirement hop by hop. The tail-end node also needs to know the 841 slot width of a LSP to assign the proper frequency resource. 842 Compared with [RFC6163], except identifying the resource (i.e., fixed 843 wavelength for WSON and frequency resource for flexible grids), the 844 other signaling requirements (e.g., unidirectional or bidirectional, 845 with or without converters) are the same as WSON described in the 846 section 6.1 of [RFC6163]. 848 Regarding how a GMPLS control plane can assign n and m, different 849 cases can apply: 851 a) n and m can both change. It is the effective slot what 852 matters. Some entity needs to make sure the effective frequency 853 slot remains valid. 855 b) m can change; n needs to be the same along the path. This 856 ensures that the nominal central frequency stays the same. 858 c) n and m need to be the same. 860 d)n can change, m needs to be the same. 862 In consequence, an entity such as a PCE can make sure that the n and 863 m stay the same along the path. Any constraint (including frequency 864 slot and width granularities) is taken into account during path 865 computation. alternatively, A PCE (or a source node) can compute a 866 path and the actual frequency slot assignment is done, for example, 867 with a distributed (signaling) procedure: 869 Each downstream node ensures that m is >= requested_m. 871 Since a downstream node cannot foresee what an upstream node will 872 allocate in turn, a way we can ensure that the effective frequency 873 slot is valid is then by ensuring that the same "n" is allocated. 874 By forcing the same n, we avoid cases where the effective 875 frequency slot of the media channel is invalid (that is, the 876 resulting frequency slot cannot be described by its n and m 877 parameters). 879 Maybe this is a too hard restriction, since a node (or even a 880 centralized/combined RSA entity) can make sure that the resulting 881 end to end (effective) frequency slot is valid, even if n is 882 different locally. That means, the effective (end to end) 883 frequency slot that characterizes the media channel is one and 884 determined by its n and m, but are logical, in the sense that they 885 are the result of the intersection of local (filters) freq slots 886 which may have different freq. slots 888 For Figure Figure 15 the effective slot is valid by ensuring that the 889 minimum m is greater than the requested m. The effective slot 890 (intersection) is the lowest m (bottleneck). 892 For Figure Figure 16 the effective slot is valid by ensuring that it 893 is valid at each hop in the upstream direction. The intersection 894 needs to be computed. Invalid slots could result otherwise. 896 |Path(m_req) | ^ | 897 |---------> | # | 898 | | # ^ 899 -^--------------^----------------#----------------#-- 900 Effective # # # # 901 FS n, m # . . . . . . .#. . . . . . . . # . . . . . . . .# <-fixed 902 # # # # n 903 -v--------------v----------------#----------------#--- 904 | | # v 905 | | # Resv | 906 | | v <------ | 907 | | |flowspec(n, m_a)| 908 | | <--------| | 909 | | flowspec (n, | 910 <--------| min(m_a, m_b)) 911 flowspec (n, | 912 min(m_a, m_b, m_c)) 914 Figure 15: Distributed allocation with different m and same n 916 |Path(m_req) ^ | 917 |---------> # | | 918 | # ^ ^ 919 -^-------------#----------------#-----------------#-------- 920 Effective # # # # 921 FS n, m # # # # 922 # # # # 923 -v-------------v----------------#-----------------#-------- 924 | | # v 925 | | # Resv | 926 | | v <------ | 927 | | |flowspec(n_a, m_a) 928 | | <--------| | 929 | | flowspec (FSb [intersect] FSa) 930 <--------| 931 flowspec ([intersect] FSa,FSb,FSc) 933 Figure 16: Distributed allocation with different m and different n 935 Note, when a media channel is bound to one OCh-P (i.e is a Network 936 media channel), the EFS must be the one of the Och-P. The media 937 channel setup by the LSP may contains the EFS of the network media 938 channel EFS. This is an endpoint property, the egress and ingress 939 SHOULD constrain the EFS to Och-P EFS . 941 5.6. Neighbor Discovery and Link Property Correlation 943 Potential interworking problems between fixed-grid DWDM and flexible- 944 grid DWDM nodes, may appear. Additionally, even two flexible-grid 945 optical nodes may have different grid properties, leading to link 946 property conflict. 948 Devices or applications that make use of the flexible-grid may not be 949 able to support every possible slot width. In other words, 950 applications may be defined where different grid granularity can be 951 supported. Taking node F as an example, an application could be 952 defined where the nominal central frequency granularity is 12.5 GHz 953 requiring slot widths being multiple of 25 GHz. Therefore the link 954 between two optical nodes with different grid granularity must be 955 configured to align with the larger of both granularities. Besides, 956 different nodes may have different slot width tuning ranges. 958 In summary, in a DWDM Link between two nodes, at least the following 959 properties should be negotiated: 961 Grid capability (channel spacing) - Between fixed-grid and 962 flexible-grid nodes. 964 Grid granularity - Between two flexible-grid nodes. 966 Slot width tuning range - Between two flexible-grid nodes. 968 5.7. Path Computation / Routing and Spectrum Assignment (RSA) 970 Much like in WSON, in which if there is no (available) wavelength 971 converters in an optical network, an LSP is subject to the 972 ''wavelength continuity constraint'' (see section 4 of [RFC6163]), if 973 the capability of shifting or converting an allocated frequency slot, 974 the LSP is subject to the Optical ''Spectrum Continuity Constraint''. 976 Because of the limited availability of wavelength/spectrum converters 977 (sparse translucent optical network) the wavelength/spectrum 978 continuity constraint should always be considered. When available, 979 information regarding spectrum conversion capabilities at the optical 980 nodes may be used by RSA (Routing and Spectrum Assignment) 981 mechanisms. 983 The RSA process determines a route and frequency slot for a LSP. 984 Hence, when a route is computed the spectrum assignment process (SA) 985 should determine the central frequency and slot width based on the 986 slot width and available central frequencies information of the 987 transmitter and receiver, and the available frequency ranges 988 information and available slot width ranges of the links that the 989 route traverses. 991 5.7.1. Architectural Approaches to RSA 993 Similar to RWA for fixed grids, different ways of performing RSA in 994 conjunction with the control plane can be considered. The approaches 995 included in this document are provided for reference purposes only; 996 other possible options could also be deployed. 998 5.7.1.1. Combined RSA (R&SA) 1000 In this case, a computation entity performs both routing and 1001 frequency slot assignment. The computation entity should have the 1002 detailed network information, e.g. connectivity topology constructed 1003 by nodes/links information, available frequency ranges on each link, 1004 node capabilities, etc. 1006 The computation entity could reside either on a PCE or the ingress 1007 node. 1009 5.7.1.2. Separated RSA (R+SA) 1011 In this case, routing computation and frequency slot assignment are 1012 performed by different entities. The first entity computes the 1013 routes and provides them to the second entity; the second entity 1014 assigns the frequency slot. 1016 The first entity should get the connectivity topology to compute the 1017 proper routes; the second entity should get the available frequency 1018 ranges of the links and nodes' capabilities information to assign the 1019 spectrum. 1021 5.7.1.3. Routing and Distributed SA (R+DSA) 1023 In this case, one entity computes the route but the frequency slot 1024 assignment is performed hop-by-hop in a distributed way along the 1025 route. The available central frequencies which meet the spectrum 1026 continuity constraint should be collected hop by hop along the route. 1027 This procedure can be implemented by the GMPLS signaling protocol. 1029 5.8. Routing / Topology dissemination 1031 In the case of combined RSA architecture, the computation entity 1032 needs to get the detailed network information, i.e. connectivity 1033 topology, node capabilities and available frequency ranges of the 1034 links. Route computation is performed based on the connectivity 1035 topology and node capabilities; spectrum assignment is performed 1036 based on the available frequency ranges of the links. The 1037 computation entity may get the detailed network information by the 1038 GMPLS routing protocol. Compared with [RFC6163], except wavelength- 1039 specific availability information, the connectivity topology and node 1040 capabilities are the same as WSON, which can be advertised by GMPLS 1041 routing protocol (refer to section 6.2 of [RFC6163]. This section 1042 analyses the necessary changes on link information brought by 1043 flexible grids. 1045 5.8.1. Available Frequency Ranges/slots of DWDM Links 1047 In the case of flexible grids, channel central frequencies span from 1048 193.1 THz towards both ends of the C band spectrum with 6.25 GHz 1049 granularity. Different LSPs could make use of different slot widths 1050 on the same link. Hence, the available frequency ranges should be 1051 advertised. 1053 5.8.2. Available Slot Width Ranges of DWDM Links 1055 The available slot width ranges needs to be advertised, in 1056 combination with the Available frequency ranges, in order to verify 1057 whether a LSP with a given slot width can be set up or not; this is 1058 is constrained by the available slot width ranges of the media matrix 1059 Depending on the availability of the slot width ranges, it is 1060 possible to allocate more spectrum than strictly needed by the LSP. 1062 5.8.3. Spectrum Management 1064 [Editors' note: the part on the hierarchy of the optical spectrum 1065 could be confusing, we can discuss it]. The total available spectrum 1066 on a fiber could be described as a resource that can be divided by a 1067 media device into a set of Frequency Slots. In terms of managing 1068 spectrum, it is necessary to be able to speak about different 1069 granularities of managed spectrum. For example, a part of the 1070 spectrum could be assigned to a third party to manage. This need to 1071 partition creates the impression that spectrum is a hierarchy in view 1072 of Management and Control Plane. The hierarchy is created within a 1073 management system, and it is an access right hierarchy only. It is a 1074 management hierarchy without any actual resource hierarchy within 1075 fiber. The end of fiber is a link end and presents a fiber port 1076 which represents all of spectrum available on the fiber. Each 1077 spectrum allocation appears as Link Channel Port (i.e., frequency 1078 slot port) within fiber. 1080 5.8.4. Information Model 1082 Fixed DM grids can also be described via suitable choices of slots in 1083 a flexible DWDM grid. However, devices or applications that make use 1084 of the flexible grid may not be capable of supporting every possible 1085 slot width or central frequency position. Following is the 1086 definition of information model, not intended to limit any IGP 1087 encoding implementation. For example, information required for 1088 routing/path selection may be the set of available nominal central 1089 frequencies from which a frequency slot of the required width can be 1090 allocated. A convenient encoding for this information (may be as a 1091 frequency slot or sets of contiguous slices) is further study in IGP 1092 encoding document. 1094 ::= 1095 1096 1097 1098 1099 1101 ::= 1102 [< Available Frequency Range-List>] 1104 ::= 1105 | 1106 1108 ::= n A— 6.25GHz, 1109 where n is positive integer, such as 6.25GHz, 12.5GHz, 25GHz, 50GHz 1110 or 100GHz 1112 ::= m A— 12.5GHz, 1113 where m is positive integer 1115 ::= j x 12.5GHz, 1116 j is a positive integer 1118 ::= k x 12.5GHz, 1119 k is a positive integer (k >= j) 1121 Figure 17: Routing Information model 1123 6. Control Plane Requirements 1125 The GMPLS based control plane of a flexi-grid networks provides 1126 aditional requirements to GMPLS. In this section the features to be 1127 covered by GMPLS signaling for flexi-grid are identified. [Editor's 1128 note: Only discussed requirements are included at this stage. 1129 Routing requirements will come in the next version] 1131 6.1. Support for Media Channels 1133 The control plane SHALL be able to support Media Channels, 1134 characterized by a single frequency slot. The representation of the 1135 Media Channel in the GMPLS Control plane is the so-called flexi-grid 1136 LSP. Since network media channels are media channels, an LSP may 1137 also be the control plane representation of a network media channel. 1138 Consequently, the control plane SHALL be able to support Network 1139 Media Channels. 1141 The signaling procedure SHALL be able to configure the nominal 1142 central frequency (n) of a flexi-grid LSP. 1144 The control plane protocols SHALL allow flexible range of values for 1145 the frequency slot width (m) parameter. Specifically, the control 1146 plane SHALL allow setting up a media channel with frequency slot 1147 width (m) ranging from a minimum of m=1 (12.5GHz) to a maximum of the 1148 entire C-band with a slot width granularity of 12.5GHz. 1150 The signaling procedure of the GMPLS control plane SHALL be able to 1151 configure the minimum width (m) of a flexi-grid LSP. In adition, the 1152 control plane SHALL be able to configure local frecuency slots, 1154 The control plane architecture SHOULD allow for the support of L-band 1155 and S-band 1157 The signalling process of the control plane SHALL allow to collect 1158 the local frequency slot asigned at each link along the path 1160 6.2. Support for Media Channel Resizing 1162 The control plane SHALL allow resizing (grow or shrink) the frequency 1163 slot width of a media channel/network media channel. The resizing 1164 MAY imply resizing the local frequency slots along the path of the 1165 flexi-grid LSP. 1167 6.3. Support for Logical Associations of multiple media channels 1169 A set of media channels can be used to transport signals that have a 1170 logical association between them. The control plane architecture 1171 SHOULD allow multiple media channels to be logically associated. The 1172 control plane SHOULD allow the co-routing of a set of media channels 1173 logically associated 1175 7. Security Considerations 1177 TBD 1179 8. Contributing Authors 1181 Qilei Wang 1182 ZTE 1183 Ruanjian Avenue, Nanjing, China 1184 wang.qilei@zte.com.cn 1186 Malcolm Betts 1187 ZTE 1188 malcolm.betts@zte.com.cn 1190 Xian Zhang 1191 Huawei 1192 zhang.xian@huawei.com 1194 Cyril Margaria 1195 Nokia Siemens Networks 1196 St Martin Strasse 76, Munich, 81541, Germany 1197 +49 89 5159 16934 1198 cyril.margaria@nsn.com 1200 Sergio Belotti 1201 Alcatel Lucent 1202 Optics CTO 1203 Via Trento 30 20059 Vimercate (Milano) Italy 1204 +39 039 6863033 1205 sergio.belotti@alcatel-lucent.com 1207 Yao Li 1208 Nanjing University 1209 wsliguotou@hotmail.com 1210 Fei Zhang 1211 ZTE 1212 Zijinghua Road, Nanjing, China 1213 zhang.fei3@zte.com.cn 1215 Lei Wang 1216 ZTE 1217 East Huayuan Road, Haidian district, Beijing, China 1218 wang.lei131@zte.com.cn 1220 Guoying Zhang 1221 China Academy of Telecom Research 1222 No.52 Huayuan Bei Road, Beijing, China 1223 zhangguoying@ritt.cn 1225 Takehiro Tsuritani 1226 KDDI R&D Laboratories Inc. 1227 2-1-15 Ohara, Fujimino, Saitama, Japan 1228 tsuri@kddilabs.jp 1230 Lei Liu 1231 KDDI R&D Laboratories Inc. 1232 2-1-15 Ohara, Fujimino, Saitama, Japan 1233 le-liu@kddilabs.jp 1235 Eve Varma 1236 Alcatel-Lucent 1237 +1 732 239 7656 1238 eve.varma@alcatel-lucent.com 1240 Young Lee 1241 Huawei 1243 Jianrui Han 1244 Huawei 1246 Sharfuddin Syed 1247 Infinera 1248 Rajan Rao 1249 Infinera 1251 Marco Sosa 1252 Infinera 1254 Biao Lu 1255 Infinera 1257 Abinder Dhillon 1258 Infinera 1260 Felipe Jimenez Arribas 1261 TelefA^3nica I+D 1263 Andrew G. Malis 1264 Verizon 1266 Adrian Farrel 1267 Old Dog Consulting 1269 Daniel King 1270 Old Dog Consulting 1272 Huub van Helvoort 1274 9. Acknowledgments 1276 The authors would like to thank Pete Anslow for his insights and 1277 clarifications. This work was supported in part by the FP-7 IDEALIST 1278 project under grant agreement number 317999. 1280 10. References 1282 10.1. Normative References 1284 [G.694.1] International Telecomunications Union, "ITU-T 1285 Recommendation G.694.1, Spectral grids for WDM 1286 applications: DWDM frequency grid", November 2012. 1288 [G.709] International Telecomunications Union, "ITU-T 1289 Recommendation G.709, Interfaces for the Optical Transport 1290 Network (OTN).", March 2009. 1292 [G.800] International Telecomunications Union, "ITU-T 1293 Recommendation G.800, Unified functional architecture of 1294 transport networks.", February 2012. 1296 [G.805] International Telecomunications Union, "ITU-T 1297 Recommendation G.805, Generic functional architecture of 1298 transport networks.", March 2000. 1300 [G.8080] International Telecomunications Union, "ITU-T 1301 Recommendation G.8080/Y.1304, Architecture for the 1302 automatically switched optical network", 2012. 1304 [G.870] International Telecomunications Union, "ITU-T 1305 Recommendation G.870/Y.1352, Terms and definitions for 1306 optical transport networks", November 2012. 1308 [G.872] International Telecomunications Union, "ITU-T 1309 Recommendation G.872, Architecture of optical transport 1310 networks, draft v0.16 2012/09 (for discussion)", 2012. 1312 [G.959.1-2013] 1313 International Telecomunications Union, "Update of ITU-T 1314 Recommendation G.959.1, Optical transport network physical 1315 layer interfaces (to appear in July 2013)", 2013. 1317 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1318 Requirement Levels", BCP 14, RFC 2119, March 1997. 1320 [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching 1321 (GMPLS) Architecture", RFC 3945, October 2004. 1323 [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) 1324 Hierarchy with Generalized Multi-Protocol Label Switching 1325 (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005. 1327 [RFC5150] Ayyangar, A., Kompella, K., Vasseur, JP., and A. Farrel, 1328 "Label Switched Path Stitching with Generalized 1329 Multiprotocol Label Switching Traffic Engineering (GMPLS 1330 TE)", RFC 5150, February 2008. 1332 [RFC6163] Lee, Y., Bernstein, G., and W. Imajuku, "Framework for 1333 GMPLS and Path Computation Element (PCE) Control of 1334 Wavelength Switched Optical Networks (WSONs)", RFC 6163, 1335 April 2011. 1337 10.2. Informative References 1339 [RFC4397] Bryskin, I. and A. Farrel, "A Lexicography for the 1340 Interpretation of Generalized Multiprotocol Label 1341 Switching (GMPLS) Terminology within the Context of the 1342 ITU-T's Automatically Switched Optical Network (ASON) 1343 Architecture", RFC 4397, February 2006. 1345 Authors' Addresses 1347 Oscar Gonzalez de Dios (editor) 1348 Telefonica I+D 1349 Don Ramon de la Cruz 82-84 1350 Madrid 28045 1351 Spain 1353 Phone: +34913128832 1354 Email: ogondio@tid.es 1356 Ramon Casellas (editor) 1357 CTTC 1358 Av. Carl Friedrich Gauss n.7 1359 Castelldefels Barcelona 1360 Spain 1362 Phone: +34 93 645 29 00 1363 Email: ramon.casellas@cttc.es 1365 Fatai Zhang 1366 Huawei 1367 Huawei Base, Bantian, Longgang District 1368 Shenzhen 518129 1369 China 1371 Phone: +86-755-28972912 1372 Email: zhangfatai@huawei.com 1374 Xihua Fu 1375 ZTE 1376 Ruanjian Avenue 1377 Nanjing 1378 China 1380 Email: fu.xihua@zte.com.cn 1381 Daniele Ceccarelli 1382 Ericsson 1383 Via Calda 5 1384 Genova 1385 Italy 1387 Phone: +39 010 600 2512 1388 Email: daniele.ceccarelli@ericsson.com 1390 Iftekhar Hussain 1391 Infinera 1392 140 Caspian Ct. 1393 Sunnyvale 94089 1394 USA 1396 Phone: 408-572-5233 1397 Email: ihussain@infinera.com