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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: December 2014 G.Zhang 5 CATR 6 X.Fu 7 ZTE 8 R. Casellas 9 CTTC 10 Y.Wang 11 CATR 12 June 20, 2014 14 Link Management Protocol Extensions for Grid Property Negotiation 15 draft-ietf-ccamp-grid-property-lmp-00.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. 26 Internet-Drafts are draft documents valid for a maximum of six 27 months and may be updated, replaced, or obsoleted by other documents 28 at any time. It is inappropriate to use Internet-Drafts as 29 reference material or to cite them other than as "work in progress." 30 The list of current Internet-Drafts can be accessed at 31 http://www.ietf.org/ietf/1id-abstracts.txt 32 The list of Internet-Draft Shadow Directories can be accessed at 33 http://www.ietf.org/shadow.html 34 This Internet-Draft will expire on December 20, 2014. 36 Copyright Notice 38 Copyright (c) 2014 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with 46 respect to this document. Code Components extracted from this 47 document must include Simplified BSD License text as described in 48 Section 4.e of the Trust Legal Provisions and are provided without 49 warranty as described in the Simplified BSD License. 51 Abstract 52 The recent updated version of ITU-T [G.694.1] has introduced the 53 flexible-grid DWDM technique, which provides a new tool that operators 54 can implement to provide a higher degree of network optimization than 55 is possible with fixed-grid systems. This document describes the 56 extensions to the Link Management Protocol (LMP) to negotiate link grid 57 property between the adjacent DWDM nodes before the link is brought up. 59 Table of Contents 60 1. Introduction...................................................3 61 1.1. Conventions Used in This Document.........................3 62 2. Terminology....................................................3 63 3. Requirements for Grid Property Negotiation.....................4 64 3.1. Flexi-fixed Grid Nodes Interworking.......................4 65 3.2. Flexible-Grid Capability Negotiation......................5 66 3.3. Summary...................................................5 67 4. LMP extensions.................................................6 68 4.1. Grid Property Subobject...................................6 69 5. Messages Exchange Procedure....................................8 70 5.1. Flexi-fixed Grid Nodes Messages Exchange..................8 71 5.2. Flexible Nodes Messages Exchange..........................9 72 6. Security Considerations.......................................10 73 7. IANA Considerations...........................................10 74 8. References....................................................10 75 8.1. Normative references.....................................10 76 8.2. Informative References...................................11 77 9. Authors' Address..............................................11 78 10. Contributors' Address........................................12 80 1. Introduction 82 The recent updated version of ITU-T [G.694.1] has introduced the 83 flexible-grid DWDM technique, which provides a new tool that 84 operators can implement to provide a higher degree of network 85 optimization than is possible with fixed-grid systems. A flexible- 86 grid network supports allocating a variable-sized spectral slot to a 87 channel. Flexible-grid DWDM transmission systems can allocate their 88 channels with different spectral bandwidths/slot widths so that they 89 can be optimized for the bandwidth requirements of the particular 90 bit rate and modulation scheme of the individual channels. This 91 technique is regarded to be a promising way to improve the spectrum 92 utilization efficiency and can be used in the beyond 100Gb/s 93 transport systems. 95 Fixed-grid DWDM system is regarded as a special case of Flexi-grid 96 DWDM. It is expected that fixed-grid optical nodes will be gradually 97 replaced by flexible nodes and interworking between fixed-grid DWDM 98 and flexible-grid DWDM nodes will be needed as the network evolves. 99 Additionally, even two flexible-grid optical nodes may have 100 different grid properties based on the filtering component 101 characteristics, thus need to negotiate on the specific parameters 102 to be used during neighbor discovery process [draft-ietf-ccamp- 103 flexi-grid-fwk-00]. This document describes the extensions to the 104 Link Management Protocol (LMP) to negotiate a link grid property 105 between two adjacent Flexi-grid nodes before the link is brought up. 106 1.1. Conventions Used in This Document 107 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 108 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 109 document are to be interpreted as described in RFC 2119 [RFC2119]. 111 2. Terminology 113 For the flexible-grid DWDM, the spectral resource is called 114 frequency slot which is represented by the central frequency and the 115 slot width. The defined nominal central frequency and the slot width 116 can be referred to [FLEX-FWK]. 118 In this contribution, some other definitions are listed below: 120 Central frequency granularity: It is the granularity of the allowed 121 central frequencies and is set to the multiple of 6.25 GHz. 122 Slot width granularity: It is the granularity of the allowed slot 123 width, and is set to the multiple of 12.5 GHz. 125 Tuning range: It describes the supported spectrum slot range of the 126 switching nodes or interfaces. It is represented by the supported 127 minimal slot width and the maximum slot width. 129 Channel spacing: It is used in traditional fixed-grid network to 130 identify spectrum spacing between two adjacent channels. 132 3. Requirements for Grid Property Negotiation 134 3.1. Flexi-fixed Grid Nodes Interworking 135 Figure 1 shows an example of interworking between flexible and 136 fixed-grid nodes. Node A, B, D and E support flexible-grid. All 137 these nodes can support frequency slots with a central frequency 138 granularity of 6.25 GHz and slot width granularity of 12.5 GHz. 139 Given the flexibility in flexible-grid nodes, it is possible to 140 configure the nodes in such a way that the central frequencies and 141 slot width parameters are backwards compatible with the fixed DWDM 142 grids (adjacent flexible frequency slots with channel spacing of 143 8*6.25 and slot width of 4*12.5 GHz is equivalent to fixed DWDM 144 grids with channel spacing of 50 GHz). 145 As node C can only support the fixed-grid DWDM property with channel 146 spacing of 50 GHz, to establish a LSP through node B, C, D, the 147 links between B to C and C to D must set to align with the fixed- 148 grid values. This link grid property must be negotiated before 149 establishing the LSP. 151 +---+ +---+ +---+ +---+ +---+ 152 | A |---------| B |=========| C |=========| D +--------+ E | 153 +---+ +---+ +---+ +---+ +---+ 154 Figure 1 An example of interworking between 155 flexible and fixed-grid nodes 157 ^ ^ ^ ^ 158 ------->|<----50GHz---->|<----50GHz---->|<----50GHz---->|<------ 159 ..... | | | | ..... 160 +-------+-------+-------+-------+-------+--------+------+-------+- 161 n=-2 -1 0 1 2 162 Fixed channel spacing of 50 GHz (Node C) 163 ^ ^ ^ ^ 164 | | | | 166 --------+---------------+---------------+---------------+--------- 167 ..... | n=-8, m=4 | n=0, m=4 | n=8, m=4 | ..... 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 169 n=-16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 170 |_| 171 Flexi-grid (Nodes B,D) 6.25 GHz 172 Central frequency granularity=6.25 GHz 173 Slot width granularity=12.5 GHz 174 Figure 2 Representation of fixed channel spacing 175 and flexi-grid spectrum slot 177 3.2. Flexible-Grid Capability Negotiation 179 The updated version of ITU-T [G.694.1] has defined the flexible-grid 180 with a central frequency granularity of 6.25 GHz and a slot width 181 granularity of 12.5 GHz. However, devices or applications that make 182 use of the flexible-grid may not be able to support every possible 183 slot width. In other words, applications may be defined where 184 different grid granularity can be supported. Taking node G as an 185 example, an application could be defined where the central frequency 186 granularity is 12.5 GHz requiring slot widths being multiple of 25 187 GHz. Therefore the link between two optical nodes with different 188 grid granularity must be configured to align with the larger of both 189 granularities. Besides, different nodes may have different slot 190 width tuning ranges. For example, in figure 3, node F can only 191 support slot width with tuning change from 12.5 to 100 GHz, while 192 node G supports tuning range from 25 GHz to 200 GHz. The link 193 property of slot width tuning range for the link between F and G 194 should be chosen as the range intersection, resulting in a range 195 from 25 GHz to 100 GHz. 196 +---+ +---+ 197 | F +------------| G | 198 +---+ +---+ 199 +------------------+-------------+-----------+ 200 | Unit (GHz) | Node F | Node G | 201 +------------------+-------------+-----------+ 202 | Grid granularity | 6.25 (12.5) | 12.5 (25) | 203 +------------------+-------------+-----------+ 204 | Tuning range | [12.5, 100] | [25, 200] | 205 +------------------+-------------+-----------+ 206 Figure 3 An example of flexible-grid capability negotiation 208 3.3. Summary 210 In summary, in a DWDM Link between two nodes, the following 211 properties can be negotiated: 213 o Grid capability: flexible grid or fixed grid DWDM. 215 o Central frequency granularity: a multiplier of 6.25 GHz. 217 o Slot width granularity: a multiplier of 12.5 GHz. 219 o Slot width tuning range: two multipliers of 12.5GHz, each 220 indicate the minimal and maximal slot width supported by a port 221 respectively. 223 4. LMP extensions 224 4.1. Grid Property Subobject 226 According to [RFC4204], the LinkSummary message is used to verify 227 the consistency of the link property on both sides of the link 228 before it is brought up. The LinkSummary message contains negotiable 229 and non-negotiable DATA_LINK objects, carrying a series of variable- 230 length data items called subobjects, which illustrate the detailed 231 link properties. The subobjects are defined in Section 12.12.1 in 232 [RFC4204]. 233 To solve the problems stated in section 3, this draft extends the 234 LMP protocol by introducing a new DATA_LINK subobject called "Grid 235 property", allowing the grid property correlation between adjacent 236 nodes. The encoding format of this new subobject is as follows: 238 0 1 2 3 239 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 1 240 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 241 | Type | Length | Reserved | 242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 243 | Grid | C.F.G | S.W.G | Min | Max | 244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 246 Type=TBD, Grid property type. 248 Grid: 249 The value is used to represent which grid the node/interface 250 supports. Values defined in [RFC6205] identify DWDM [G.694.1] and 251 CWDM [G.694.2]. The value defined in [I-D.farrkingel-ccamp- 252 flexigrid-lambda-label] identifies flexible DWDM. 253 +---------------+-------+ 255 | Grid | Value | 256 +---------------+-------+ 257 | Reserved | 0 | 258 +---------------+-------+ 259 | ITU-T DWDM | 1 | 260 +---------------+-------+ 261 | ITU-T CWDM | 2 | 262 +---------------+-------+ 263 | Flexible DWDM | 3 | 264 +---------------+-------+ 265 | Future use | 4-16 | 266 +---------------+-------+ 268 C.F.G (central frequency granularity): 270 For a fixed-grid node/interface, the C.F.G value is used to 271 represent the channel spacing, as the spacing between adjacent 272 channels is constant. For a flexible-grid node/interface, this field 273 should be used to represent the central frequency granularity which 274 is the multiple of 6.25 GHz. 276 +------------+-------+ 277 | C.F.G (GHz) | Value | 278 +------------+-------+ 279 | Reserved | 0 | 280 +------------+-------+ 281 | 100 | 1 | 282 +------------+-------+ 283 | 50 | 2 | 284 +------------+-------+ 285 | 25 | 3 | 286 +------------+-------+ 287 | 12.5 | 4 | 288 +------------+-------+ 289 | 6.25 | 5 | 290 +------------+-------+ 291 | Future use | 6-15 | 292 +------------+-------+ 294 S.W.G (Slot Width Granularity): 296 It is a positive integer value which indicates the slot width 297 granularity which is the multiple of 12.5 GHz. 299 Min & Max: 301 Min & Max indicate the slot width tuning range the interface 302 supports (as defined in section 2). For example, for slot width 303 tuning range from 25 GHz to 100 GHz (with regard to a node with slot 304 width granularity of 12.5 GHz), the values of Min and Max should be 305 2 and 8 respectively. For fixed-grid nodes, these two fields are 306 meaningless and should be set to zero. 308 5. Messages Exchange Procedure 310 5.1. Flexi-fixed Grid Nodes Messages Exchange 311 To demonstrate the procedure of grid property correlation, the model 312 shown in Figure 1 is reused. Node B starts sending messages. 314 o After inspecting its own node/interface property, node B sends 315 node C a LinkSummary message including the MESSAGE ID, TE_LINK ID 316 and DATA_LINK objects. The setting and negotiating of MESSAGE ID 317 and TE_link ID can be referenced to [RFC4204]. As node B 318 supports flexible-grid property, the Grid and C.S. values in the 319 grid property subobject are set to be 3 and 5 respectively. The 320 slot width tuning range is from 12.5 GHz to 200 GHz. Meanwhile, 321 the N bit of the DATA_LINK object is set to 1, indicating that 322 the property is negotiable. 323 o When node C receives the LinkSummary message from B, it checks 324 the Grid, C.S., Min and Max values in the grid property subobject. 325 Node C can only support fixed-grid DWDM and realizes that the 326 flexible-grid property is not acceptable for the link. Since the 327 receiving N bit in the DATA_LINK object is set, indicating that 328 the Grid property of B is negotiable, node C responds to B with a 329 LinkSummaryNack containing a new Error_code object and state that 330 the property needs further negotiation. Meanwhile, an accepted 331 grid property subobject (Grid=2, C.S.=2, fixed DWDM with channel 332 spacing of 50 GHz) is carried in LinkSummaryNack message. At 333 this moment, the N bit in the DATA_LINK object is set to 0, 334 indicating that the grid property subobject is non-negotiable. 336 o As the channel spacing and slot width of node B can be configured 337 to be any integral multiples of 6.25 GHz and 12.5 GHz 338 respectively, node B supports the fixed DWDM values announced by 339 node C. Consequently, node B will resend the LinkSummary message 340 carrying the grid property subobject with values of Grid=2 and 341 C.S.=2. 343 o Once received the LinkSummary message from node B, node C replies 344 with a LinkSummaryACK message. After the message exchange, the 345 link between node B and C is brought up with a fixed channel 346 spacing of 50 GHz. 348 In the above mentioned grid property correlation scenario, the node 349 supporting a flexible-grid is the one that starts sending LMP 350 messages. The procedure where the initiator is the fixed-grid node 351 is as follows: 353 o After inspecting its own interface property, Node C sends B a 354 LinkSummary message containing a grid property subobject with 355 Grid=2, C.S.=2. The N bit in the DATA_LINK object is set to 0, 356 indicating that it is non-negotiable. 358 o As the channel spacing and slot width of node B can be configured 359 to be any integral multiples of 6.25 GHz and 12.5 GHz 360 respectively, node B is able to support the fixed DWDM parameters. 361 Then, node B will make appropriate configuration and reply node C 362 the LinkSummaryACK message. 364 o After the message exchange, the link between node B and C is 365 brought up with a fixed channel spacing of 50 GHz. 367 5.2. Flexible Nodes Messages Exchange 369 To demonstrate the procedure of grid property correlation between to 370 flexi-grid capable nodes, the model shown in figure 3 is reused. The 371 procedure of grid property correlation (negotiating the grid 372 granularity and slot width tuning range) is similar to the scenarios 373 mentioned above. 374 o The Grid, C.S., Min and Max values in the grid property subobject 375 sent from node F to G are set to be 3,5,1,8 respectively. 376 Meanwhile, the N bit of the DATA_LINK object is set to 1, 377 indicating that the grid property is negotiable. 379 o When node G has received the LinkSummary message from F, it will 380 analyze the Grid, C.S., Min and Max values in the Grid property 381 subobject. But node G can only support grid granularity of 12.5 382 GHz and a slotwdith tuning range from 25 GHz to 200 GHz. 383 Considering the property of node F, node G then will respond F a 384 LinkSummaryNack containing a new Error_code object and state that 385 the property need further negotiation. Meanwhile, an accepted 386 grid property subobject (Grid=3, C.S.=4, Min=1, Max=4, the slot 387 width tuning range is set to the intersection of Node F and G) is 388 carried in LinkSummaryNack message. Meanwhile, the N bit in the 389 DATA_LINK object is set to 1, indicating that the grid property 390 subobject is non-negotiable. 392 o As the channel spacing and slot width of node F can be configured 393 to be any integral multiples of 6.25 GHz and 12.5 GHz 394 respectively, node F can support the lager granularity. The 395 suggested slot width tuning range is acceptable for node F. In 396 consequence, node F will resend the LinkSummary message carrying 397 the grid subobject with values of Grid=3, C.S.=4, Min=1 and Max=4. 399 o Once received the LinkSummary message from node F, node G replies 400 with a LinkSummaryACK message. After the message exchange, the 401 link between node F and G is brought up supporting central 402 frequency granularity of 12.5 GHz and slot width tuning range 403 from 25 GHz to 100 GHz. 405 From the perspective of the control plane, once the links have been 406 brought up, wavelength constraint information can be advertised and 407 the wavelength label can be assigned hop-by-hop when establishing a 408 LSP based on the link grid property. 410 6. Security Considerations 412 TBD. 413 7. IANA Considerations 415 TBD. 416 8. References 417 8.1. Normative references 419 [G.694.1] International Telecommunications Union, "Spectral grids 420 for WDM applications: DWDM frequency grid", Recommendation 421 G.694.1, June 2002. 422 [G.694.2] International Telecommunications Union, "Spectral grids 423 for WDM applications: CWDM wavelength grid", 424 Recommendation G.694.2, December 2003. 426 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 427 Requirement Levels", BCP 14, RFC 2119, March 1997. 429 [RFC4204] Lang, J., "Link Management Protocol (LMP)", RFC 4204, 430 October 2005. 432 [RFC6205] Otani, T. and D. Li, "Generalized Labels for Lambda- 433 Switch-Capable (LSC) Label Switching Routers", RFC 6205, 434 March 2011. 436 8.2. Informative References 438 [I-D.farrkingel-ccamp-flexigrid-lambda-label] 439 Farrel, A., King, D., Li, Y., Zhang, F., 440 "Generalized Labels for the Flexi-Grid in Lambda-Switch- 441 Capable (LSC) Label Switching Routers", draft-farrkingel- 442 ccamp-flexigrid-lambda-label-08 (work in progress), 443 February 2014. 445 [FLEX-FWK] 446 Dios, O., Casellas, R., Zhang, F., Fu, X., Ceccarelli, D., 447 and I. Hussain, "Framework for GMPLS based control of 448 Flexi-grid DWDM networks", draft-ietf-ccamp-flexi-grid- 449 fwk-00 (work in progress), October 2013. 451 9. Authors' Address 452 Yao Li (editor) 454 ZTE 455 Email: li.yao3@zte.com.cn 457 Guoying Zhang (editor) 458 China Academy of Telecom Research, MIIT 460 Email: zhangguoying@catr.cn 462 Xihua Fu (editor) 464 ZTE 466 Email: fu.xihua@zte.com.cn 468 Ramon Casellas 470 CTTC 472 Email: ramon.casellas@cttc.es 474 Yu Wang 476 China Academy of Telecom Research, MIIT 477 Email: wangyu@catr.cn 479 10. Contributors' Address 481 Wenjuan He (editor) 482 ZTE 484 Email: he.wenjuan1@zte.com.cn