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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group CCAMP 2 Internet Draft Y.Li 3 Intended status: Informational ZTE 4 Expires: August 2014 G. Zhang 5 CATR 6 X.Fu 7 ZTE 8 R. Casellas 9 CTTC 10 Y Wang 11 CATR 12 February 14, 2014 14 Link Management Protocol Extensions for Grid Property Negotiation 15 draft-li-ccamp-grid-property-lmp-03.txt 17 Status of this Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF), its areas, and its working groups. Note that 24 other groups may also distribute working documents as Internet- 25 Drafts. 27 Internet-Drafts are draft documents valid for a maximum of six 28 months and may be updated, replaced, or obsoleted by other documents 29 at any time. It is inappropriate to use Internet-Drafts as 30 reference material or to cite them other than as "work in progress." 32 The list of current Internet-Drafts can be accessed at 33 http://www.ietf.org/ietf/1id-abstracts.txt 35 The list of Internet-Draft Shadow Directories can be accessed at 36 http://www.ietf.org/shadow.html 38 This Internet-Draft will expire on August 10, 2014. 40 Copyright Notice 42 Copyright (c) 2014 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info)in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with 50 respect to this document. Code Components extracted from this 51 document must include Simplified BSD License text as described in 52 Section 4.e of the Trust Legal Provisions and are provided without 53 warranty as described in the Simplified BSD License. 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 60 respect to this document. 62 Abstract 64 The recent updated version of ITU-T [G.694.1] has introduced the 65 flexible-grid DWDM technique, which provides a new tool that operators 66 can implement to provide a higher degree of network optimization than 67 is possible with fixed-grid systems. This document describes the 68 extensions to the Link Management Protocol (LMP) to negotiate link grid 69 property between the adjacent DWDM nodes before the link is brought up. 71 Table of Contents 73 1. Introduction ................................................ 3 74 1.1. Conventions Used in This Document ....................... 3 75 2. Terminology ................................................. 3 76 3. Requirements for Grid Property Negotiation ................... 4 77 3.1. Flexi-fixed Grid Nodes Interworking ..................... 4 78 3.2. Flexible-Grid Capability Negotiation .................... 5 79 3.3. Summary ................................................ 5 80 4. LMP extensions .............................................. 6 81 4.1. Grid Property Subobject................................. 6 82 5. Messages Exchange Procedure.................................. 8 83 5.1. Flexi-fixed Grid Nodes Messages Exchange ................ 8 84 5.2. Flexible Nodes Messages Exchange ........................ 9 85 6. Security Considerations..................................... 10 86 7. IANA Considerations ........................................ 10 87 8. References ................................................. 10 88 8.1. Normative references................................... 10 89 8.2. Informative References................................. 11 90 9. Authors' Address ........................................... 11 91 10. Contributors' Address...................................... 12 93 1. Introduction 95 The recent updated version of ITU-T [G.694.1] has introduced the 96 flexible-grid DWDM technique, which provides a new tool that 97 operators can implement to provide a higher degree of network 98 optimization than is possible with fixed-grid systems. A flexible- 99 grid network supports allocating a variable-sized spectral slot to a 100 channel. Flexible-grid DWDM transmission systems can allocate their 101 channels with different spectral bandwidths/slot widths so that they 102 can be optimized for the bandwidth requirements of the particular 103 bit rate and modulation scheme of the individual channels. This 104 technique is regarded to be a promising way to improve the spectrum 105 utilization efficiency and can be used in the beyond 100Gb/s 106 transport systems. 108 Fixed-grid DWDM system is regarded as a special case of Flexi-grid 109 DWDM. It is expected that fixed-grid optical nodes will be gradually 110 replaced by flexible nodes and interworking between fixed-grid DWDM 111 and flexible-grid DWDM nodes will be needed as the network evolves. 112 Additionally, even two flexible-grid optical nodes may have 113 different grid properties based on the filtering component 114 characteristics, thus need to negotiate on the specific parameters 115 to be used during neighbor discovery process [draft-ietf-ccamp- 116 flexi-grid-fwk-00]. This document describes the extensions to the 117 Link Management Protocol (LMP) to negotiate a link grid property 118 between two adjacent Flexi-grid nodes before the link is brought up. 120 1.1. Conventions Used in This Document 122 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 123 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 124 document are to be interpreted as described in RFC 2119 [RFC2119]. 126 2. Terminology 128 For the flexible-grid DWDM, the spectral resource is called 129 frequency slot which is represented by the central frequency and the 130 slot width. The defined nominal central frequency and the slot width 131 can be referred to [FLEX-FWK]. 133 In this contribution, some other definitions are listed below: 135 Central frequency granularity: It is the granularity of the allowed 136 central frequencies and is set to the multiple of 6.25 GHz. 138 Slot width granularity: It is the granularity of the allowed slot 139 width, and is set to the multiple of 12.5 GHz. 141 Tuning range: It describes the supported spectrum slot range of the 142 switching nodes or interfaces. It is represented by the supported 143 minimal slot width and the maximum slot width. 145 Channel spacing: It is used in traditional fixed-grid network to 146 identify spectrum spacing between two adjacent channels. 148 3. Requirements for Grid Property Negotiation 150 3.1. Flexi-fixed Grid Nodes Interworking 152 Figure 1 shows an example of interworking between flexible and 153 fixed-grid nodes. Node A, B, D and E support flexible-grid. All 154 these nodes can support frequency slots with a central frequency 155 granularity of 6.25 GHz and slot width granularity of 12.5 GHz. 156 Given the flexibility in flexible-grid nodes, it is possible to 157 configure the nodes in such a way that the central frequencies and 158 slot width parameters are backwards compatible with the fixed DWDM 159 grids (adjacent flexible frequency slots with channel spacing of 160 8*6.25 and slot width of 4*12.5 GHz is equivalent to fixed DWDM 161 grids with channel spacing of 50 GHz). 163 As node C can only support the fixed-grid DWDM property with channel 164 spacing of 50 GHz, to establish a LSP through node B, C, D, the 165 links between B to C and C to D must set to align with the fixed- 166 grid values. This link grid property must be negotiated before 167 establishing the LSP. 169 +---+ +---+ +---+ +---+ +---+ 170 | A |---------| B |=========| C |=========| D +--------+ E | 171 +---+ +---+ +---+ +---+ +---+ 172 Figure 1 An example of interworking between 173 flexible and fixed-grid nodes 175 ^ ^ ^ ^ 176 ------->|<----50GHz---->|<----50GHz---->|<----50GHz---->|<------ 177 ..... | | | | ..... 178 +-------+-------+-------+-------+-------+--------+------+-------+- 179 n=-2 -1 0 1 2 180 Fixed channel spacing of 50 GHz (Node C) 181 ^ ^ ^ ^ 182 | | | | 183 --------+---------------+---------------+---------------+--------- 184 ..... | n=-8, m=4 | n=0, m=4 | n=8, m=4 | ..... 185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 186 n=-16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 187 |_| 188 Flexi-grid (Nodes B,D) 6.25 GHz 189 Central frequency granularity=6.25 GHz 190 Slot width granularity=12.5 GHz 191 Figure 2 Representation of fixed channel spacing 192 and flexi-grid spectrum slot 194 3.2. Flexible-Grid Capability Negotiation 196 The updated version of ITU-T [G.694.1] has defined the flexible-grid 197 with a central frequency granularity of 6.25 GHz and a slot width 198 granularity of 12.5 GHz. However, devices or applications that make 199 use of the flexible-grid may not be able to support every possible 200 slot width. In other words, applications may be defined where 201 different grid granularity can be supported. Taking node G as an 202 example, an application could be defined where the central frequency 203 granularity is 12.5 GHz requiring slot widths being multiple of 25 204 GHz. Therefore the link between two optical nodes with different 205 grid granularity must be configured to align with the larger of both 206 granularities. Besides, different nodes may have different slot 207 width tuning ranges. For example, in figure 3, node F can only 208 support slot width with tuning change from 12.5 to 100 GHz, while 209 node G supports tuning range from 25 GHz to 200 GHz. The link 210 property of slot width tuning range for the link between F and G 211 should be chosen as the range intersection, resulting in a range 212 from 25 GHz to 100 GHz. 214 +---+ +---+ 215 | F +------------| G | 216 +---+ +---+ 217 +------------------+-------------+-----------+ 218 | Unit (GHz) | Node F | Node G | 219 +------------------+-------------+-----------+ 220 | Grid granularity | 6.25 (12.5) | 12.5 (25) | 221 +------------------+-------------+-----------+ 222 | Tuning range | [12.5, 100] | [25, 200] | 223 +------------------+-------------+-----------+ 225 Figure 3 An example of flexible-grid capability negotiation 227 3.3. Summary 229 In summary, in a DWDM Link between two nodes, the following 230 properties can be negotiated: 232 o Grid capability: flexible grid or fixed grid DWDM. 234 o Central frequency granularity: a multiplier of 6.25 GHz. 236 o Slot width granularity: a multiplier of 12.5 GHz. 238 o Slot width tuning range: two multipliers of 12.5GHz, each 239 indicate the minimal and maximal slot width supported by a port 240 respectively. 242 4. LMP extensions 244 4.1. Grid Property Subobject 246 According to [RFC4204], the LinkSummary message is used to verify 247 the consistency of the link property on both sides of the link 248 before it is brought up. The LinkSummary message contains negotiable 249 and non-negotiable DATA_LINK objects, carrying a series of variable- 250 length data items called subobjects, which illustrate the detailed 251 link properties. The subobjects are defined in Section 12.12.1 in 252 [RFC4204]. 254 To solve the problems stated in section 3, this draft extends the 255 LMP protocol by introducing a new DATA_LINK subobject called "Grid 256 property", allowing the grid property correlation between adjacent 257 nodes. The encoding format of this new subobject is as follows: 259 0 1 2 3 260 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 1 261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 262 | Type | Length | Reserved | 263 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 264 | Grid | C.F.G | S.W.G | Min | Max | 265 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 267 Type=TBD, Grid property type. 269 Grid: 271 The value is used to represent which grid the node/interface 272 supports. Values defined in [RFC6205] identify DWDM [G.694.1] and 273 CWDM [G.694.2]. The value defined in [I-D.farrkingel-ccamp- 274 flexigrid-lambda-label] identifies flexible DWDM. 276 +---------------+-------+ 277 | Grid | Value | 278 +---------------+-------+ 279 | Reserved | 0 | 280 +---------------+-------+ 281 | ITU-T DWDM | 1 | 282 +---------------+-------+ 283 | ITU-T CWDM | 2 | 284 +---------------+-------+ 285 | Flexible DWDM | 3 | 286 +---------------+-------+ 287 | Future use | 4-16 | 288 +---------------+-------+ 290 C.F.G (central frequency granularity): 292 For a fixed-grid node/interface, the C.F.G value is used to 293 represent the channel spacing, as the spacing between adjacent 294 channels is constant. For a flexible-grid node/interface, this field 295 should be used to represent the central frequency granularity which 296 is the multiple of 6.25 GHz. 298 +------------+-------+ 299 | C.F.G (GHz) | Value | 300 +------------+-------+ 301 | Reserved | 0 | 302 +------------+-------+ 303 | 100 | 1 | 304 +------------+-------+ 305 | 50 | 2 | 306 +------------+-------+ 307 | 25 | 3 | 308 +------------+-------+ 309 | 12.5 | 4 | 310 +------------+-------+ 311 | 6.25 | 5 | 312 +------------+-------+ 313 | Future use | 6-15 | 314 +------------+-------+ 316 S.W.G (Slot Width Granularity): 318 It is a positive integer value which indicates the slot width 319 granularity which is the multiple of 12.5 GHz. 321 Min & Max: 323 Min & Max indicate the slot width tuning range the interface 324 supports (as defined in section 2). For example, for slot width 325 tuning range from 25 GHz to 100 GHz (with regard to a node with slot 326 width granularity of 12.5 GHz), the values of Min and Max should be 327 2 and 8 respectively. For fixed-grid nodes, these two fields are 328 meaningless and should be set to zero. 330 5. Messages Exchange Procedure 332 5.1. Flexi-fixed Grid Nodes Messages Exchange 334 To demonstrate the procedure of grid property correlation, the model 335 shown in Figure 1 is reused. Node B starts sending messages. 337 o After inspecting its own node/interface property, node B sends 338 node C a LinkSummary message including the MESSAGE ID, TE_LINK ID 339 and DATA_LINK objects. The setting and negotiating of MESSAGE ID 340 and TE_link ID can be referenced to [RFC4204]. As node B 341 supports flexible-grid property, the Grid and C.S. values in the 342 grid property subobject are set to be 3 and 5 respectively. The 343 slot width tuning range is from 12.5 GHz to 200 GHz. Meanwhile, 344 the N bit of the DATA_LINK object is set to 1, indicating that 345 the property is negotiable. 347 o When node C receives the LinkSummary message from B, it checks 348 the Grid, C.S., Min and Max values in the grid property subobject. 349 Node C can only support fixed-grid DWDM and realizes that the 350 flexible-grid property is not acceptable for the link. Since the 351 receiving N bit in the DATA_LINK object is set, indicating that 352 the Grid property of B is negotiable, node C responds to B with a 353 LinkSummaryNack containing a new Error_code object and state that 354 the property needs further negotiation. Meanwhile, an accepted 355 grid property subobject (Grid=2, C.S.=2, fixed DWDM with channel 356 spacing of 50 GHz) is carried in LinkSummaryNack message. At 357 this moment, the N bit in the DATA_LINK object is set to 0, 358 indicating that the grid property subobject is non-negotiable. 360 o As the channel spacing and slot width of node B can be configured 361 to be any integral multiples of 6.25 GHz and 12.5 GHz 362 respectively, node B supports the fixed DWDM values announced by 363 node C. Consequently, node B will resend the LinkSummary message 364 carrying the grid property subobject with values of Grid=2 and 365 C.S.=2. 367 o Once received the LinkSummary message from node B, node C replies 368 with a LinkSummaryACK message. After the message exchange, the 369 link between node B and C is brought up with a fixed channel 370 spacing of 50 GHz. 372 In the above mentioned grid property correlation scenario, the node 373 supporting a flexible-grid is the one that starts sending LMP 374 messages. The procedure where the initiator is the fixed-grid node 375 is as follows: 377 o After inspecting its own interface property, Node C sends B a 378 LinkSummary message containing a grid property subobject with 379 Grid=2, C.S.=2. The N bit in the DATA_LINK object is set to 0, 380 indicating that it is non-negotiable. 382 o As the channel spacing and slot width of node B can be configured 383 to be any integral multiples of 6.25 GHz and 12.5 GHz 384 respectively, node B is able to support the fixed DWDM parameters. 385 Then, node B will make appropriate configuration and reply node C 386 the LinkSummaryACK message. 388 o After the message exchange, the link between node B and C is 389 brought up with a fixed channel spacing of 50 GHz. 391 5.2. Flexible Nodes Messages Exchange 393 To demonstrate the procedure of grid property correlation between to 394 flexi-grid capable nodes, the model shown in figure 3 is reused. The 395 procedure of grid property correlation (negotiating the grid 396 granularity and slot width tuning range) is similar to the scenarios 397 mentioned above. 399 o The Grid, C.S., Min and Max values in the grid property subobject 400 sent from node F to G are set to be 3,5,1,8 respectively. 401 Meanwhile, the N bit of the DATA_LINK object is set to 1, 402 indicating that the grid property is negotiable. 404 o When node G has received the LinkSummary message from F, it will 405 analyze the Grid, C.S., Min and Max values in the Grid property 406 subobject. But node G can only support grid granularity of 12.5 407 GHz and a slotwdith tuning range from 25 GHz to 200 GHz. 408 Considering the property of node F, node G then will respond F a 409 LinkSummaryNack containing a new Error_code object and state that 410 the property need further negotiation. Meanwhile, an accepted 411 grid property subobject (Grid=3, C.S.=4, Min=1, Max=4, the slot 412 width tuning range is set to the intersection of Node F and G) is 413 carried in LinkSummaryNack message. Meanwhile, the N bit in the 414 DATA_LINK object is set to 1, indicating that the grid property 415 subobject is non-negotiable. 417 o As the channel spacing and slot width of node F can be configured 418 to be any integral multiples of 6.25 GHz and 12.5 GHz 419 respectively, node F can support the lager granularity. The 420 suggested slot width tuning range is acceptable for node F. In 421 consequence, node F will resend the LinkSummary message carrying 422 the grid subobject with values of Grid=3, C.S.=4, Min=1 and Max=4. 424 o Once received the LinkSummary message from node F, node G replies 425 with a LinkSummaryACK message. After the message exchange, the 426 link between node F and G is brought up supporting central 427 frequency granularity of 12.5 GHz and slot width tuning range 428 from 25 GHz to 100 GHz. 430 From the perspective of the control plane, once the links have been 431 brought up, wavelength constraint information can be advertised and 432 the wavelength label can be assigned hop-by-hop when establishing a 433 LSP based on the link grid property. 435 6. Security Considerations 437 TBD. 439 7. IANA Considerations 441 TBD. 443 8. References 445 8.1. Normative references 447 [G.694.1] International Telecommunications Union, "Spectral grids 448 for WDM applications: DWDM frequency grid", Recommendation 449 G.694.1, June 2002. 451 [G.694.2] International Telecommunications Union, "Spectral grids 452 for WDM applications: CWDM wavelength grid", 453 Recommendation G.694.2, December 2003. 455 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 456 Requirement Levels", BCP 14, RFC 2119, March 1997. 458 [RFC4204] Lang, J., "Link Management Protocol (LMP)", RFC 4204, 459 October 2005. 461 [RFC6205] Otani, T. and D. Li, "Generalized Labels for Lambda- 462 Switch-Capable (LSC) Label Switching Routers", RFC 6205, 463 March 2011. 465 8.2. Informative References 467 [I-D.farrkingel-ccamp-flexigrid-lambda-label] 468 Farrel, A., King, D., Li, Y., Zhang, F., 469 "Generalized Labels for the Flexi-Grid in Lambda-Switch- 470 Capable (LSC) Label Switching Routers", draft-farrkingel- 471 ccamp-flexigrid-lambda-label-08 (work in progress), 472 February 2014. 474 [FLEX-FWK] 475 Dios, O., Casellas, R., Zhang, F., Fu, X., Ceccarelli, D., 476 and I. Hussain, "Framework for GMPLS based control of 477 Flexi-grid DWDM networks", draft-ietf-ccamp-flexi-grid- 478 fwk-00 (work in progress), October 2013. 480 9. Authors' Address 482 Yao Li (editor) 484 ZTE 486 Email: li.yao3@zte.com.cn 488 Guoying Zhang (editor) 490 China Academy of Telecom Research, MIIT 492 Email: zhangguoying@catr.cn 494 Xihua Fu (editor) 496 ZTE 498 Email: fu.xihua@zte.com.cn 500 Ramon Casellas 502 CTTC 504 Email: ramon.casellas@cttc.es 505 Yu Wang 507 China Academy of Telecom Research, MIIT 509 Email: wangyu@catr.cn 511 10. Contributors' Address 513 Wenjuan He (editor) 515 ZTE 517 Email: he.wenjuan1@zte.com.cn