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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Qilei Wang 3 Internet-Draft Xihua Fu 4 Intended status: Standards Track ZTE Corporation 5 Expires: April 25, 2013 Oct 22, 2012 7 RSVP-TE Extensions for GMPLS control of Spectrum Switched Optical 8 Networks (SSONs) 9 draft-wang-ccamp-gmpls-sson-rsvpte-02.txt 11 Abstract 13 A new architecture of optical transport networks which is addressed 14 in the newest version of G.872 is being developed in ITU-T SG15. 15 Compared with previous G.872 technology, this new technology allows 16 the switch of large chunk of contiguous spectrum which may be wider 17 than the spectrum occupied by a single optical channel signal. 19 Since current control plane technology isn't able to control this 20 kind of application, this document describes the signaling extension 21 to support the control of this kind of new spectrum utilization and 22 implementation way. This document also addresses the interworking 23 between WSON optical channel and SSON (Spectrum Switched Optical 24 Network) optical channel. 26 Status of this Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on April 25, 2013. 43 Copyright Notice 45 Copyright (c) 2012 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 61 1.1. Conventions used in this document . . . . . . . . . . . . 4 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 63 3. Requirements and Modeling of SSON . . . . . . . . . . . . . . 5 64 3.1. Hierarchy between Optical Channel and Media Channel . . . 5 65 3.2. Switching Type . . . . . . . . . . . . . . . . . . . . . . 6 66 3.3. Media Channel . . . . . . . . . . . . . . . . . . . . . . 6 67 3.3.1. Label Format . . . . . . . . . . . . . . . . . . . . . 6 68 3.3.2. Traffic Parameters . . . . . . . . . . . . . . . . . . 6 69 3.3.3. Grid Attributes of Forwarding Adjacency . . . . . . . 7 70 3.4. Optical Channel . . . . . . . . . . . . . . . . . . . . . 7 71 3.4.1. Overview of Flexible Grid and Fixed Grid . . . . . . . 7 72 3.4.2. Interwork between WSON OCh signal and SSON OCh 73 signal . . . . . . . . . . . . . . . . . . . . . . . . 7 74 4. Signaling Protocol Extensions to Support Control of Media 75 Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 76 4.1. Switching Type . . . . . . . . . . . . . . . . . . . . . . 9 77 4.2. Label Format Extensions of Media Channel Layer . . . . . . 9 78 4.3. Traffic Parameters of Media Channel Layer . . . . . . . . 10 79 5. Signaling Procedures . . . . . . . . . . . . . . . . . . . . . 10 80 5.1. RSVP-TE Signaling Procedures to Support the Setup of 81 Frequency Slot Channel . . . . . . . . . . . . . . . . . . 10 82 5.1.1. Centralized Spectrum Assignment . . . . . . . . . . . 10 83 5.1.2. Distributed Spectrum Assignment . . . . . . . . . . . 10 84 5.2. Interwork between WSON signal and SSON signal . . . . . . 11 85 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 86 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 87 7.1. Normative References . . . . . . . . . . . . . . . . . . . 13 88 7.2. Informative References . . . . . . . . . . . . . . . . . . 13 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 91 1. Introduction 93 In the newest version of G.872, a new kind of spectrum utilization 94 and implementation way is introduced to current optical network. A 95 new kind of entity called media channel which is similar to LSP is 96 introduced. According to the description in [G.872v16], the media 97 channel is a topological construct that represents both the path 98 through the media and the resource (frequency slot) that it occupies. 99 A media channel is bounded by ports on media elements. A media 100 channel may be dimensioned to carry more than one OCh-P signal. That 101 is to say, a chunk of contiguous spectrum which can be occupied by a 102 group of optical channels can be forwarded via wide-band filters as a 103 whole without filtering and switching everything down to the 104 individual OCh (Optical Channel) level in long-haul systems. 105 Compared with narrowband, wideband filters and switching has many 106 advantages, for example, building OCh Signals for management 107 convenience, maximizing the reach and traversing more nodes. 109 Following is the description taken from [G.872v16], "below the OCh, 110 the entities that provide for configuration of the media channels are 111 described separately from the entities that provide management of the 112 collections of the OCh-P signals that traverse the media". According 113 to the description, we can conclude that the containment relationship 114 exists between media channels and OCh signals, and the containment 115 relationship should be announced to the source and end nodes of the 116 media channels. Intermediate nodes are unnecessary to know the 117 containment relationship because the media channel can be switched as 118 a whole without filtering and switching everything down to individual 119 OCh level. 121 Two kinds of entities which are spectrum configuration entity and 122 signal management entity should be provide by nodes creating media 123 channels from the perspective of control plane. 125 Note: Optical channels switched in a media channel may have different 126 spectrum bandwidth. 128 From the perspective of management plane and control plane, 129 containment relationship indicates that hierarchy exists between the 130 media channel and optical channel. GMPLS protocol are needed to 131 extent to help manage this kind of spectrum utilization and 132 implementation way. This document first describes the coexistence of 133 media channel and optical channel, then the layer model base on the 134 hierarchy between optical channels (OCh) and media channel from 135 management plane or control plane perspective and defines signaling 136 protocol extension to support the control of media channel. As the 137 flexible grid framework document describes both the media channel and 138 optical channel, this document also give a detail description about 139 the interworking between WSON optical channel and SSON (Spectrum 140 Switched Optical Network) optical channel. 142 1.1. Conventions used in this document 144 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 145 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 146 document are to be interpreted as described in [RFC2119]. 148 2. Terminology 150 o Frequency slot: As defined by Q6 in clause 3.1.2 of G.694.1, a 151 frequency slot is a frequency range which is allocated to a slot 152 and unavailable to other slots within a flexible grid. A 153 frequency slot is defined by its nominal central frequency and its 154 slot width. Detailed description can be found in the framework 155 document. 157 o Media channel: as defined in [G.872v16], media channel is used to 158 indicate a media association that represents both the topology 159 (i.e., the path through the media) and the resource (frequency 160 slot) that it occupies. A media channel is bounded by ports on 161 media elements and can span any combination of network elements 162 and fibers. 164 o Effective frequency slot: The effective frequency slot of a media 165 channel is that part of the frequency slots of the filters along 166 the media channel that is common to all of the filters' frequency 167 slots. It is described by its nominal central frequency and its 168 slot width. 170 o Nominal central frequency (of a frequency slot) - as used by Q6/ 171 SG15 in G.694.1. This parameter is associated with a grid 172 position on the fixed grid and a slot in the flexible grid. 174 o Network media channel: The end-to-end channel allocated to 175 transport a single OCh payload signal is called a network media 176 channel and supports a single OCh payload network connection. 178 o SSON: Spectrum-Switched Optical Network. This concept and 179 definition is introduced from the framework document. An optical 180 network in which a data plane connection is switched based on an 181 optical spectrum frequency slot of a variable slot width, rather 182 than based on a fixed grid and fixed slot width. 184 3. Requirements and Modeling of SSON 186 3.1. Hierarchy between Optical Channel and Media Channel 188 Spectrum may be allocated in larger and contiguous piece than 189 spectrum occupied by a single optical channel which is called 190 Frequency Slot. The frequency slot is described by its nominal 191 central frequency and its slot width [ITU-T G.694.1]. The media 192 Channel is a topological construct that represents both the path 193 through the media and the resource (frequency slot) that it occupies. 194 A media channel is bounded by ports on media elements and can span 195 any combination of network elements and fibers, while the frequency 196 slot is a local concept, while the media channel has an end-to-end 197 meaning. A media channel may be dimensioned to carry more than one 198 OCh P signal. Network media channel is a specific type of media 199 channel which can only be used to transport a single OCh signal and 200 support a single OCh connection. 202 From the perspective of control plane or management plane, hierarchy 203 exists between media channel and optical channel, as media channel 204 can be used to transport optical channel signals. During the process 205 of path setup, containment relationship between optical channel 206 signal and media channel should be conveyed through signaling and 207 announced to source node and end node in order to help group and 208 detach optical channel signals from one another. Dependency 209 relationship needs to be explicitly told. 211 Notes: no hierarchy exists in either media channels or optical 212 channels. 214 Media channels can be switched in a media Matrix. The media channel 215 matrix provides flexible connectivity for the media channels. Media 216 ports at the edge of a media channel matrix may be created and broken 217 to help route media channel path. Media channel connection will 218 limit the connectivity of optical channel signals over the network 219 element within the frequency slot. Media channel matrixes are not 220 mandatory to have the function of optical channel matrix as signals 221 in the media channel can be switched as a whole. 223 In the case where the switching granularity of the media Matrix 224 allows for independent switching of each OCh, it can be decided as a 225 matter of policy that a request to establish an OCh connection will, 226 internal to the NE, establish a network media channel Matrix 227 Connection of the same spectrum slot width, and the network media 228 Matrix Connection can be released when the OCh connection is 229 released. 231 As more than one optical channel signal can be carried in a media 232 channel, notion of hierarchy exists between them. current optical 233 transport network can be modeled into two layers and managed 234 independently from the perspective of management, one is optical 235 channel layer and the other is media layer. Optical channel layer 236 can be modeled as higher layer and media channel layer can be modeled 237 as lower layer. Media layer LSP created in high layer appear as a 238 data link in optical channel layer. One or more optical channel LSPs 239 can be nested into media channel LSP. That is to say, media channel 240 LSP appears as a H-LSP in the higher layer optical channel LSP. 242 As a kind of resource, spectrum allows for the utilization by both 243 optical channel layer and media layer. It's not necessary to setup 244 media LSP first before the setup of OCh LSP. Coexistence of OCh and 245 media channel in the same link is permitted. 247 3.2. Switching Type 249 Switching type can be used to indicate the type of switching that 250 should be performed on a particular link. According to the modeling 251 in the previous section, a new switching type should be defined to 252 indicate the switching capability of media channel layer. 254 3.3. Media Channel 256 3.3.1. Label Format 258 Section 3.3 of [RFC3471] defines waveband switching: "A waveband 259 represents a set of contiguous wavelengths which can be switched 260 together to a new waveband". This is similar to the media channel 261 switching, because they both switch multiple wavelengths or spectrum 262 as a unit. 264 But the wavelength label defined in [RFC3471] only has significance 265 between neighbors, in order to control the setup and release of media 266 channel with RSVP-TE signaling, a new media channel label which has 267 definite information of nominal central frequency and slot width of 268 the spectrum is needed. This chunk of spectrum can be used for 269 subsequent setup of optical channel path. 271 3.3.2. Traffic Parameters 273 In current network, like MPLS network, OTN network, signaling can be 274 used to reserve bandwidth (i.e., bitrates) at each node along the 275 path when set up LSPs. The bandwidth information describes the end- 276 to-end traffic characteristic of a LSP, so the signaling SHOULD be 277 able to carry bandwidth information that a LSP need to occupy. 279 In the process of the setup of media channel, the most critical 280 traffic characteristic of a media channel LSP is spectrum, i.e., the 281 spectrum width that a LSP can occupy. For example, if a third party 282 wants to manage and operate a chunk of spectrum by itself, carrier 283 could use the signaling to set up a media channel with a specific 284 spectrum width to satisfy the requirement. Carrier doesn't care how 285 this spectrum can be used by the party and how many data this chunk 286 of spectrum can bear. So when we use signaling to set up a media 287 channel, spectrum resource information (i.e.,spectrum width) should 288 be carried in the signaling to reserve the spectrum resource along 289 the path. 291 3.3.3. Grid Attributes of Forwarding Adjacency 293 Media matrix connection may interconnect one or more media channels, 294 which in turn may carry one or more OCh signals. In the case the 295 media matrix just allow the switching of spectrum as a whole, 296 internal flexible grid or fixed grid attributes are unnecessary to be 297 known by the forwarding adjacency end points. 299 3.4. Optical Channel 301 [Notes: This section mainly addresses the current status of optical 302 channel interconnection, including interconnection between WSON 303 optical channel signal and SSON optical channel signal.] 305 3.4.1. Overview of Flexible Grid and Fixed Grid 307 Fixed grid signals have fixed slot width (e.g., 50GHz), while 308 flexible grid signals allow different slot widths (e.g., 50GHz, 309 87.5GHz).GMPLS and PCE control of fixed grid network (i.e., WSON, 310 Wavelength Switched Optical Network) is close to mature in IETF 311 CCAMP, while flexible grid control plane technology is still being 312 developed in IETF. This section mainly focuses on the 313 interconnection between WSON optical channel signal and SSON optical 314 channel signal. 316 3.4.2. Interwork between WSON OCh signal and SSON OCh signal 318 Some open issues are listed in the recent flexible grid framework 319 document and still need to be resolved if we want to push the 320 framework document forward. Part of these issues which may have 321 relation to the interwork between SSON and WSON are listed here: 323 1). If a new switching capability is needed to represent SSON 324 optical channel layer? 326 2). Potential problems with having the same switching capability but 327 the label format changes compared with WSON optical channel layer. 329 3). Role of LSP encoding type? I think the issue listed here 330 intends to say if a new LSP encoding type is needed for flexible grid 331 optical channel layer. 333 4). Notion of hierarchy? There is no notion of hierarchy between 334 flexible grid OCh and fixed grid OCh. 336 Just from my perspective, I think SSON optical channel layer should 337 use the same switching capability as WSON optical channel layer. 338 Some words are given here to describe my opinion. A LSP which has a 339 bandwidth of 50GHz pass through both WSON network and SSON network. 340 We assume that no OEOs exist in the LSP, so both the WSON optical 341 channel path and SSON optical channel path occupy 50GHz. From the 342 perspective of data plane, there is no change of the signal and no 343 multiplexing when the WSON optical channel path interconnects with 344 SSON optical channel path. From this scenario we can conclude that 345 both WSON optical channel layer and SSON optical channel layer belong 346 to the same layer. No notion of hierarchy exists between them. Base 347 on these words, I think both WSON optical channel layer and SSON 348 optical channel layer should use the same switching capability. 350 The previous words mention the issues 1) and 4). Another two issues 351 are to be discussed in the following description in the process of 352 path setup. 354 Because there is no notion of hierarchy exists between WSON optical 355 channel layer and SSON optical channel layer, hierarchy LSP which is 356 addressed in [RFC4206] and [RFC6107] can't be applied. But stitching 357 LSP which is described in [RFC5150] can be applied in one layer. LSP 358 hierarchy allows more than one LSP to be mapped to an H-LSP, but in 359 case of S-LSP, at most one LSP may be associated with an S-LSP. This 360 is similar to the scenario of interconnection between WSON OCh LSP 361 and SSON OCh LSP. Similar to an H-LSP, an S-LSP could be managed and 362 advertised, although it is not required, as a TE link, either in the 363 same TE domain as it was provisioned or a different one. Path setup 364 procedure of stitching LSP can be applied in the scenario of 365 interconnection between WSON optical channel path and SSON optical 366 channel path. 368 4. Signaling Protocol Extensions to Support Control of Media Layer 370 This section mainly addresses the signaling protocol extension in 371 order to support the control of spectrum-switched optical network 372 media layer and the facilitating of the setup of forwarding adjacency 373 in G.872 optical transport network. 375 4.1. Switching Type 377 A new switching type is defined here for media channel layer. 379 Value Type 380 ------- ------- 381 XX(IANA) Media Channel Switched Capable (MCSC) 383 Figure 1: Switching Capability 385 4.2. Label Format Extensions of Media Channel Layer 387 According to the description in the section 3.2, label should be able 388 to describe the frequency slot characteristic in order to facilitate 389 the switch of this large piece of spectrum. Label format of flexible 390 grid can be introduced here to depict the label of media channel. 392 0 1 2 3 393 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 1 394 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 395 |Grid | C.S. | Identifier | n | 396 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 397 | m | Reserved | 398 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 400 Figure 2: label 402 Grid Type: 3. A new grid value to support flexible grid. 404 The meaning of C.S. and identifier is maintained from [RFC6205] and 405 [draft-farrkingel-ccamp-flexigrid-lambda-label]. 407 Similar to the definition in 408 [draft-farrkingel-ccamp-flexigrid-lambda-label], n is used to 409 identify the nominal central frequency, and m (16bits) is used to 410 identify slot width of the media channel. 412 [Notes: here we use 16 bits to represent the "m" value, because 8 413 bits maybe not enough for the setup of media channel with large chunk 414 of spectrum. This document is different from current flexible grid 415 document in CCAMP because of different model way.] 417 4.3. Traffic Parameters of Media Channel Layer 419 Similar to the original signaling which carry the information of 420 Bandwidth (i.e., bitrates) that a LSP may reserve at each node along 421 the path, signaling that is used to set up media channel SHOULD be 422 able to carry the information of spectrum width. The spectrum width 423 traffic parameters can be organized as follow, and this information 424 is carried in the Sender_Tspec object within a path message. 426 0 1 2 3 427 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 428 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 429 | m | Reserved | 430 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 432 Figure 3: traffic parameter 434 m (16 bits): the spectrum width is specified by m*12.5 GHz. 436 5. Signaling Procedures 438 5.1. RSVP-TE Signaling Procedures to Support the Setup of Frequency 439 Slot Channel 441 5.1.1. Centralized Spectrum Assignment 443 In this case, both of the route and the frequency slot information 444 (i.e., central frequency and spectrum width) are provided by the PCE 445 or ingress node. When signaling a LSP, the assigned label 446 information is carried in the ERO label sub-object which is addressed 447 in [RFC3473]. When the nodes along the LSP receive the path message 448 carrying the ERO and ERO label sub-object, the procedure of path 449 setup is the same as the procedure which is described in [RFC3473] 450 and [RFC4003]. RRO and RRO label sub-object are used to record the 451 label information of the egress. 453 5.1.2. Distributed Spectrum Assignment 455 In this case, only the route is provided by a PCE or ingress node 456 before the signaling procedure. The available spectrum SHALL be 457 collected hop by hop and the egress node SHOULD select a proper label 458 for the LSP. After the route is computed, the ingress node SHOULD 459 find out the available spectrum for the LSP on the next link of the 460 route. 462 Then a path message is sent to the next node along the path according 463 to the route information. The path message MUST contain a 464 Sender_Tspec object to specify the spectrum width of the media 465 channel. A Label_set object SHALL be added to the path message, 466 which contains the candidate available spectrum for the LSP on the 467 next link. 469 When an intermediate node receives the path message, it can deserve 470 the spectrum width information from the Sender_Tspec object. Then it 471 SHOULD find the available spectrum for the LSP on the next link of 472 the route similar to the ingress node. The common part of the two 473 available spectrum sets. If the new set is null, the path message 474 SHALL be rejected by a patherr message. Otherwise, the Label_set 475 object in the path message SHALL be updated according to the new set 476 and the path message is forwarded to the next node according to the 477 route. 479 When an egress node receives a path message, it SHOULD select an 480 available spectrum from the Label_set object based on local policy 481 and determine the media channel base on the spectrum width and the 482 available spectrum. Then a Resv message is responded so that the 483 nodes along the LSP can establish the optical cross-connect based on 484 the Label object which is determined by the spectrum width in the 485 traffic parameters and the available spectrum in the Label_set 486 object. 488 5.2. Interwork between WSON signal and SSON signal 490 The path setup procedure of WSON OCh signal's interworking with SSON 491 OCh signal is described as follows: 493 Let's take the following network into consideration. 495 e2e LSP 496 +++++++++++++++++++++++++++++++++++> (LSP1-2) 498 LSP segment (flexi-LSP) 499 ====================> (LSP-AB) 500 C --- E --- G 501 /|\ | / |\ 502 / | \ | / | \ 503 R1 ---- A \ | \ | / | / B --- R2 504 \| \ |/ |/ 505 D --- F --- H 507 fixed grid --A-- flexi-grid --B-- fixed grid 509 Figure 4: Interworking between WSON OCh and SSON OCh 511 In this scenario, R1 and R2 are traditional WSON signal capable 512 nodes, A and B are both WSON optical channel signal and SSON optical 513 channel signal capable nodes, the other nodes are SSON optical 514 channel capable nodes. We assume that a 40Gbit/s LSP from R1 to R2 515 needs to be set up. 517 Node R1 prepares signaling path message for the end-to-end path setup 518 from R1 to the destination node R2. Before R1 sends path message, R1 519 should fist send a path computation request to the path computation 520 element in order to compute an end-to-end path from R1 to R2. After 521 path computation, PCRep message which contains ERO and label 522 information is send back to R1 from PCE. 524 R1 encapsulates the path message which contains ERO to explicitly 525 indicate the path and label used and RRO to record the path traversed 526 and label used by node traversed. Then R1 sends the path message to 527 the next hop node A. Here we assume path computation element is 528 capable of fixed grid and flexible grid path computation, and the ERO 529 contain the path information (R1, A, B, R2). When the path message 530 arrives at node A, node A verifies the path message and finds 531 incomplete ERO information, then send another path computation 532 request message to the PCE in order to obtain the whole path 533 information. PCE sends path computation response message which 534 contain ERO (A, D, F, H, B) and label information. Here the label is 535 flexible label information which is addressed in [draft-farrkingel]. 537 To facilitate the control of stitching LSP boundaries, we may use a 538 different encoding type for flexible grid to help control. Encoding 539 type can be used to help stitching LSP boundaries control. Stitching 540 LSP boundaries control looks like FA-LSP boundaries control, but has 541 many differences. 543 After matching the switching type and encoding type of the interface, 544 Node A blocks the signaling process and decides to set up a stitching 545 LSP according to the flexible grid LSP setup procedure using another 546 signaling process. Procedure for set up stitching LSP can be found 547 in RFC5150. The stitching LSP can be seen as a TE link in the fixed 548 grid network. After the setup of stitching LSP between A and B, A 549 then continues the blocking signaling procedure and sends the path 550 message to the next hop B directly and finishes the end-to-end LSP. 552 In this scenario of interconnection between WSON OCh and SSON OCh, 553 dynamic stitching LSP setup is frequent, static stitching LSP 554 configuration may not be needed here. 556 6. Security Considerations 558 TBD 560 7. References 562 7.1. Normative References 564 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 565 Requirement Levels", BCP 14, RFC 2119, March 1997. 567 [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching 568 (GMPLS) Architecture", RFC 3945, October 2004. 570 7.2. Informative References 572 [G.694.1 v6] 573 International Telecommunications Union, "Draft revised 574 G.694.1 version 1.6". 576 [G.872 v16] 577 International Telecommunications Union, "Draft revised 578 Recommendation ITU-T G.872". 580 [flexible-grid-ospf-ext] 581 Fatai Zhang, Xiaobing Zi, Ramon Casellas, O. Gonzalez de 582 Dios, and D. Ceccarelli, "GMPLS OSPF-TE Extensions in 583 support of Flexible-Grid in DWDM Networks", 584 draft-zhang-ccamp-flexible-grid-ospf-ext-00.txt . 586 [flexible-grid-requirements] 587 Fatai Zhang, Xiaobing Zi, O. Gonzalez de Dios, and Ramon 588 Casellas, "Requirements for GMPLS Control of Flexible 589 Grids", 590 draft-zhang-ccamp-flexible-grid-requirements-01.txt . 592 [flexigrid-lambda-label] 593 D. King, A. Farrel, Y. Li, F. Zhang, and R. Casellas, 594 "Generalized Labels for the Flexi-Grid in Lambda-Switch- 595 Capable (LSC) Label Switching Routers", 596 draft-farrkingel-ccamp-flexigrid-lambda-label-01.txt . 598 [ospf-ext-constraint-flexi-grid] 599 L Wang, Y Li, "OSPF Extensions for Routing Constraint 600 Encoding in Flexible-Grid Networks", 601 draft-wangl-ccamp-ospf-ext-constraint-flexi-grid-00.txt . 603 Authors' Addresses 605 Qilei Wang 606 ZTE Corporation 608 Email: wang.qilei@zte.com.cn 610 Xihua Fu 611 ZTE Corporation 612 ZTE Plaza, No.10, Tangyan South Road, Gaoxin District 613 Xi'an 614 P.R.China 616 Email: fu.xihua@zte.com.cn