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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document doesn't use any RFC 2119 keywords, yet seems to have RFC 2119 boilerplate text. -- The document date (October 18, 2012) is 4201 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Missing Reference: 'G.694.1' is mentioned on line 85, but not defined == Unused Reference: 'RFC2328' is defined on line 417, but no explicit reference was found in the text Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Zhang 3 Internet-Draft YL. Zhao 4 Intended status: Informational ZY. Yu 5 Expires: April 21, 2013 BUPT 6 XF. Lin 7 DJ. Wang 8 XH. Fu 9 ZTE Corporation 10 October 18, 2012 12 OSPF-TE Protocol Extension for Constraint-aware RSA in Flexi-Grid 13 Networks 14 draft-zhangj-ccamp-flexi-grid-ospf-te-ext-02 16 Abstract 18 ITU-T Study Group 15 has introduced a new flexible grids technology 19 of DWDM network which is an effective solution to improve the 20 efficiency of spectrum resource utilization. This memo extends the 21 OSPF-TE protocol to support constraint-aware routing and spectrum 22 assignment (RSA) in flexi-grid networks. 24 Status of this Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at http://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on April 21, 2013. 41 Copyright Notice 43 Copyright (c) 2012 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 2. Conventions Used in This Document . . . . . . . . . . . . . . 3 60 3. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 3 61 4. Motivation for Routing Protocol Extension . . . . . . . . . . 4 62 4.1. Constraints Considerations for RSA . . . . . . . . . . . . 4 63 4.2. Consecutive Spectrum Slots Information . . . . . . . . . . 5 64 4.3. Spectrum Compactness . . . . . . . . . . . . . . . . . . . 5 65 4.4. Variable Guard Band Information . . . . . . . . . . . . . 6 66 4.5. Modulation level Information . . . . . . . . . . . . . . . 6 67 5. OSPF-TE Protocol Extension . . . . . . . . . . . . . . . . . . 6 68 5.1. Consecutive Spectrum Slots Weight Sub-TLV . . . . . . . . 7 69 5.2. Spectrum Compactne Sub-TLV . . . . . . . . . . . . . . . . 8 70 6. Super-Channel Label Encoding Format with GB . . . . . . . . . 9 71 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 72 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 73 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 74 9.1. Normative References . . . . . . . . . . . . . . . . . . . 10 75 9.2. Informative References . . . . . . . . . . . . . . . . . . 10 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 78 1. Introduction 80 To enable the dynamic and effective allocation of spectrum resource 81 based on the demand of the client LSP's requests, the latest revision 82 of ITU-T Recommendation [G.694.1] has introduced a flexible grid 83 technique in DWDM optical networks. The flexible grid has a finer 84 granularity (i.e. according to the definition of flexible grid in 85 [G.694.1], the data channel can be selected on a channel spacing of 86 6.25 GHz with a variable slot width measured in units of 12.5 GHz) 87 for the spectrum slot. 89 In the dynamic flexi-grid networks, except for selecting an 90 appropriate route for the client LSP, the appropriate width of 91 spectrum slot is also needed to choose and assigned to the client 92 LSP. The spectrum bandwidth assigned to the client LSP is made up of 93 an appropriate number of consecutive spectrum slots from end-to-end, 94 which is determined by the used modulation format, according to the 95 client LSPs data rate requests and physical constraints of the 96 selected path. 98 Compared with ITU-T fix-grid optical network some extra constraints 99 need to be considered when running the routing and spectrum resource 100 assignment (RSA) in flexi-grid networks. In this memo two of those 101 constraints (other constraints are left for future considered) that 102 are necessary for RSA are discussed in detail in flexi-grid networks, 103 and Spectrum Compactness is introduced .and then the extension of 104 OSPF-TE protocol for these constraints related to RSA in flexi-grid 105 networks is described and also the the value of super-channel bitmap 106 member. 108 2. Conventions Used in This Document 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 3. Terminologies 116 CSSW: Consecutive spectrum slots weight 118 GB: Guard band 120 RSA: Routing and spectrum assignment 122 WSON: Wavelength switched optical networks 124 4. Motivation for Routing Protocol Extension 126 In this section we introduce the RSA constraints and the motivation 127 of routing protocol extension for of flexi-grid networks 129 4.1. Constraints Considerations for RSA 131 When processing RSA in flexi-grid networks, the constraints 132 information (such as the information of spectrum bandwidth in a 133 network link and so on.) are necessary for computing and selecting an 134 appropriate backup route and a certain number of consecutive spectrum 135 slots for the client LSPs effectively. 137 Some of the necessary constraints are listed as follows: 139 o Spectral consecutiveness constraint 141 o Variable guard band constraint 143 o Spectral continuity constraint 145 o Impairments constraint 147 o Other constraints 149 All the constraints can generate important impacts for the 150 performance of the client LSPs, even for the entire network. The 151 first two constraints are mainly talked about in this memeo. 153 Just like the wavelength continuity constraint in WSON, the spectral 154 continuity constraint means allocation of the same spectrum slots on 155 each link along a path because not all of the nodes in optical 156 networks have the ability of wavelength conversion. 158 The degradation of the optical signals due to impairments that 159 accumulate along the path (without 3R regeneration), can result in 160 unacceptable bit error rates or even a complete failure to demodulate 161 and/or detect the received 162 signal[draft-ietf-ccamp-wson-impairments-07]. So it is necessary to 163 consider about the impairments constraint within flexi-grid networks. 164 The impairments constraint in flexi-grid networks will be studied in 165 future in this memo. 167 Also, there may be some other constraints for RSA, other than the 168 four kinds above, such as the modulation levels constraint, which are 169 left for future researching. 171 4.2. Consecutive Spectrum Slots Information 173 The spectral consecutiveness constraint is that the allocated 174 spectrum slots must be chosen from consecutive spectrum slots in the 175 spectrum space on each link of flexi-grid networks. 177 Compared with the technology of WSON, the number of spectrum slots in 178 flexi-grid networks will be much larger than the number of wavelength 179 in WSON. After a long running time, the situation of available 180 spectrum slots will be much complex, especially the situation of the 181 available consecutive spectrum slots. 183 After selecting a route, the appropriate consecutive spectrum slots 184 need to be assigned for the client LSP. When we choose one of the 185 backup routes for the client LSP without considering the situation 186 about the available consecutive spectrum slots information, the route 187 may have no enough consecutive spectrum slots which means that the 188 selected route have no available resource for the LSP's request, and 189 then the client LSP will be rejected or trigger another path 190 computation process which will increase the blocking rate of the 191 network or increase network resources consumed by communication and 192 computing of new route. 194 When computing a route with the knowledge of the consecutive spectrum 195 slots information of the network link (for example, the number of ten 196 available consecutive spectrum slots in a network link, or the number 197 of twenty available consecutive spectrum slots in a network link.), 198 it will be very useful to select a better route which has higher 199 probability of enough available consecutive spectrum slots for the 200 client LSP. And this will improve the success rate of setting up new 201 client LSPs. 203 4.3. Spectrum Compactness 205 With a new client LSP arriving, a path connection needs to be 206 establish and proper consecutive of spectral resource needs to be 207 assigned to this LSP. With the LSP ending, the path connection is 208 released, and the spectral resource could be assigned for new LSP. 209 In a dynamic traffic scenario, this setup and tear down process leads 210 to fragmentation of spectrum resources Note that the probability of 211 using these pieces of fragmentations is very low since they are not 212 consecutive. If united together, e.g. one block, they could be used 213 for new LSP. This process is named defragmentation, which aim to 214 improve the utilization of spectrum resource. In order to make the 215 defragmentation more effective, the occupation of spectrum in a link 216 or in the network is needed to be better known, Spectrum Compactness 217 is proposed[OFC2012 JTh2A.35]. 219 4.4. Variable Guard Band Information 221 Some spectrum slots need to be reserved as Guard Band(GB) between two 222 adjacent client LSPs to avoid bad impact of non-linear impairments 223 and other network elements. Since the granularity of the flexi-grid 224 networks will be very small, the spectrum interval, i.e., GB need to 225 be considered more carefully to avoid poor quality impact of the 226 adjacent client LSPs. Which means with the changing of network 227 environment and the operating of the network, the bandwidth of the GB 228 also need to change. 230 In flexi-grid networks, with the increasing of the total 231 transportation power and the smaller of the channel space, the 232 channel crosstalk that results from non-linear effects will become 233 the important factor that affects the performance of the network. 234 The impact between two adjacency client LSPs may be changing based on 235 the change of crosstalk and other changes of network. With the 236 changing of those parameters, the interferences between two adjacency 237 client LSPs may be increasing, if the Guard Band is fixed, the 238 quality of the adjacent client LSPs and also the network's will be 239 decreased. If the GB can be varied based on the network environment 240 changing, then the bad impact can be avoided. 242 4.5. Modulation level Information 244 Based on OFDM, diferent modulation formats could be selected based on 245 the distance to serve different connections, since the physical 246 impairments will have high probability to degrade the quality of 247 connection requests with low-level modulation format such as OOK if 248 the distance of the connection request is very long. 250 Supposing there is a scenario, the number of a connection' hops is 251 very huge, and in some of the connection' link, there is not enough 252 spectrum resource to serve the connection if use low-level format. 253 Bandwidth resizing method can be used to solve this scenario. 254 Bandwidth resizing method is that changing the modulation format in 255 the middle node of a connection since every network node in the 256 flexible grids networks based on OFDM technology which has the 257 ability of choosing different modulation formats, which means several 258 different modulation formats could be choose in different links for a 259 connection in the flexible grids networks. So it requests that the 260 modulation formats of every links of a connection should be 261 advertised. 263 5. OSPF-TE Protocol Extension 265 In this section, we define the enhancements to the Traffic 266 Engineering (TE) properties of flexi-grid networks' TE links that can 267 be announced in OSPF-TE LSAs. 269 The TE LSA, which is an opaque 10 LSA with area flooding scope 270 [RFC3630], has only one top-level and has one or more nested sub-TLVs 271 for extensibility. [RFC3630] also defines two top Type/Length/Value 272 (TLV) triplet to support traffic engineering of OSPF, i.e. (1) Router 273 Address TLV and (2) Link TLV. In this memo, we enhance the sub-TLVs 274 for the Link TLV in support of flexi-grid networks. Specifically, we 275 add the following sub-TLVs to the Link TLV: 277 o Consecutive spectrum slots weight sub-TLV 279 o Spectrum Compactne sub-TLV 281 5.1. Consecutive Spectrum Slots Weight Sub-TLV 283 In distribution networks, we propose the CSSW as a sub-TLV of OSPF-TE 284 Link TLV which represents the situation of the available consecutive 285 spectrum slots in a link of the flexi-grid networks for example the 286 percentage of the total bandwidth of the number of five consecutive 287 spectrum slots, the percentage of the total bandwidth of the number 288 of ten consecutive spectrum slots ... ). With knowing the weight of 289 available consecutive spectrum slots in a link, the spectrum resource 290 assignment in the flexi-grid networks can be working more efficiently 291 in a distributed network. 293 slot num 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 294 slot status||||||||| |||| | | ||||||| | | | | | | | | | | 296 The figure above shows a link's spectrum status.Assume there are 20 297 slots on a link, and slot 0, slot 1, slot 2, slot 4, slot 8 and slot 298 9 are occpuded by three requests. The number of five consecutive 299 spectrum slots is 6, they are (11~15), (12~16), (13~17), (14~18), 300 (15~19). The number of ten consecutive spectrum slots is 1, and it 301 is from slot 10 to slot 10,i.e., (10~19). The number of Spectrum 302 Joint is 10. 304 The format of the CSSW sub-TLV is as follows: 306 0 1 2 3 307 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 1 308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 309 | Type = TBD | Length = variable | 310 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 311 | method| Reserve | 312 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 313 | Value : Consecutive Spectrum Slots Weight | 314 // // 315 | | 316 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 318 Type: TBD. The Type of CSSW sub-TLV is left for future to define. 319 Length: Variable. The length of CSSW sub-TLV is based on its define 320 of the value which is variable based on different implementation 321 ways. method: the method to describe the status of consecutive 322 spectrum. Value: Based on the description method of the status of 323 consecutive spectrum. 325 The content of the CSSW sub-TLV is left for future researching. 327 5.2. Spectrum Compactne Sub-TLV 329 The Spectrum Compactne sub-TLV based Defragmentation scheme which 330 indicates the occupation of spectrum in a link or in the network. 332 The format of the GB sub-TLV is as follows: 334 0 1 2 3 335 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 1 336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 337 | Type | Length | 338 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 339 | Method| Value: Spectrum Compactne | 340 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 342 Type: TBD. 344 The Type of Spectrum Compactne sub-TLV is left for future to define. 346 Length: TBD. 348 The length of Spectrum Compactne sub-TLV is based on the define of 349 the value of it. 351 Method: Represents different evaluation methods of Spectrum 352 Compactne. 354 Value: Based on the method of Spectrum Compactne evaluation. 356 The different evaluation methods of Spectrum Compactne are left for 357 future researching. 359 6. Super-Channel Label Encoding Format with GB 361 As discussed in [draft-hussain-ccamp-super-channel-label-03], the 362 Super-Channel is proposed to support flexi-grid networks. In this 363 memo, we extend the Super-Channel Label Encoding Format by 364 considering the Guard Band information. 366 0 1 2 3 367 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 1 368 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 369 | Super-Channel Id (16-bit) |Grid | S.S. | MF |R| 370 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 371 | n_start of Grid (16-bit) |Num of Slices in Grid (16-bit) | 372 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 373 |Bitmap Word #1(first set of 32 slices from the left most edge) | 374 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 375 |Bitmap Word #2 (next set of 32 contiguous slice numbers) | 376 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 377 | | 378 ... 379 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 380 |Bitmap Word #N(last set of 32 contiguous slice numbers) | 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 383 The above figure shows an encoding Format of Super-Channel Label, all 384 the fine-detail information can be accessed in 385 [draft-hussain-ccamp-super-channel-label-03], but to consider about 386 the Guard Band information, the meaning of the bitmap value is 387 changed: 0 -- reprents that slice reservation is not required 1 -- 388 reprents that slice reservation is required 2 -- reprents that slice 389 is required by Guard Band 391 MF: To show the Modulation Formates that the flexible grids networks 392 support, we add an eight bit information of MF fields. 394 R: Reserved(1-bit) 396 7. Security Considerations 398 TBD. 400 8. Acknowledgments 402 TBD. 404 9. References 406 9.1. Normative References 408 [OFC2012JTh2A.35] 409 Yu, X., Zhang, J., Zhao, Y., Peng, T., Bai, Y., Wang, D., 410 and X. Lin, "Spectrum Compactness based Defragmentation in 411 Flexible Bandwidth Optical Networks", RFC 3630, 412 September 2003. 414 [RFC2119] Bradner, S., "Key words for use in RFC's to Indicate 415 Requirement Levels", RFC 2119, March 1997. 417 [RFC2328] Moy, J., "OSPF Version 2", RFC 2328, April 1998. 419 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 420 (TE) Extensions to OSPF Version 2", RFC 3630, 421 September 2003. 423 9.2. Informative References 425 [draft-hussain-ccamp-super-channel-label-03] 426 Hussain, I., Dhillon, A., Pan, Z., Sosa, M., Basch, B., 427 Liu, S., and A. G. Malis, "Generalized Label for Super- 428 Channel Assignment on Flexible Grid", March 2012. 430 [draft-ietf-ccamp-wson-impairments-07] 431 Lee, Y., Bernstein, G., Li, D., and G. Martinelli, "A 432 Framework for the Control of Wavelength Switched Optical 433 Networks (WSON) with Impairments", July 2011. 435 Authors' Addresses 437 Jie Zhang 438 BUPT 439 No.10,Xitucheng Road,Haidian District 440 Beijing 100876 441 P.R.China 443 Phone: +8613911060930 444 Email: lgr24@bupt.edu.cn 445 URI: http://www.bupt.edu.cn/ 447 Yongli Zhao 448 BUPT 449 No.10,Xitucheng Road,Haidian District 450 Beijing 100876 451 P.R.China 453 Phone: +8613811761857 454 Email: yonglizhao@bupt.edu.cn 455 URI: http://www.bupt.edu.cn/ 457 Ziyan Yu 458 BUPT 459 No.10,Xitucheng Road,Haidian District 460 Beijing 100876 461 P.R.China 463 Phone: +8615116984347 464 Email: yzhziyan@gmail.com 465 URI: http://www.bupt.edu.cn/ 467 Xuefeng Lin 468 ZTE Corporation 469 No.16,Huayuan Road,Haidian District 470 Beijing 100191 471 P.R.China 473 Phone: +8615901011821 474 Email: lin.xuefeng@zte.com.cn 475 URI: http://www.zte.com.cn/ 476 Dajiang Wang 477 ZTE Corporation 478 No.16,Huayuan Road,Haidian District 479 Beijing 100191 480 P.R.China 482 Phone: +8613811795408 483 Email: wang.dajiang@zte.com.cn 484 URI: http://www.zte.com.cn/ 486 Xihua Fu 487 ZTE Corporation 488 West District,ZTE Plaza,No.10,Tangyan South Road,Gaoxin District 489 Xi'an 710065 490 P.R.China 492 Phone: +8613798412242 493 Email: fu.xihua@zte.com.cn 494 URI: http://www.zte.com.cn/