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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group Xian Zhang 2 Internet-Draft Haomian Zheng 3 Intended status: Informational Huawei 4 Ramon Casellas 5 CTTC 6 O. Gonzalez de Dios 7 Telefonica 8 D. Ceccarelli 9 Ericsson 10 Expires: August 14, 2014 February 14, 2014 12 GMPLS OSPF-TE Extensions in support of Flexible Grid 14 draft-zhang-ccamp-flexible-grid-ospf-ext-04.txt 16 Abstract 18 This memo describes the OSPF-TE extensions in support of GMPLS 19 control of networks that include devices that use the new flexible 20 optical grid. 22 Status of this Memo 24 This Internet-Draft is submitted to IETF in full conformance with 25 the provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF), its areas, and its working groups. Note that 29 other groups may also distribute working documents as Internet- 30 Drafts. 32 Internet-Drafts are draft documents valid for a maximum of six 33 months and may be updated, replaced, or obsoleted by other 34 documents at any time. It is inappropriate to use Internet-Drafts 35 as reference material or to cite them other than as "work in 36 progress." 38 The list of current Internet-Drafts can be accessed at 39 http://www.ietf.org/ietf/1id-abstracts.txt. 41 The list of Internet-Draft Shadow Directories can be accessed at 42 http://www.ietf.org/shadow.html. 44 This Internet-Draft will expire on August 14, 2014. 46 Copyright Notice 47 Copyright (c) 2013 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with 55 respect to this document. Code Components extracted from this 56 document must include Simplified BSD License text as described in 57 Section 4.e of the Trust Legal Provisions and are provided without 58 warranty as described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction ................................................ 2 63 2. Terminology ................................................. 3 64 2.1. Conventions Used in this Document....................... 3 65 3. Requirements for Flexi-grid Routing.......................... 3 66 3.1. Available Frequency Ranges.............................. 4 67 3.2. Application Compliance Considerations................... 5 68 3.3. Comparison with Fixed-grid DWDM Links................... 6 69 4. Extensions .................................................. 6 70 4.1. ISCD for Flexi-grid..................................... 7 71 4.2. Available Labels Set Sub-TLV............................ 7 72 4.2.1. Inclusive/Exclusive Label Range.................... 7 73 4.2.2. Inclusive/Exclusive Label Lists.................... 8 74 4.2.3. Bitmap ............................................ 8 75 4.3. Extensions to Port Label Restriction sub-TLV............ 8 76 4.4. Examples for Available Label Set Sub-TLV................ 9 77 5. IANA Considerations ........................................ 10 78 6. Implementation Status....................................... 10 79 6.1.Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)11 80 7. Acknowledgments ............................................ 12 81 8. Security Considerations..................................... 12 82 9. References ................................................. 12 83 9.1. Normative References................................... 12 84 9.2. Informative References................................. 12 85 10. Authors' Addresses......................................... 14 86 11. Contributors' Addresses.................................... 14 88 1. Introduction 90 [G.694.1] defines the Dense Wavelength Division Multiplexing (DWDM) 91 frequency grids for Wavelength Division Multiplexing (WDM) 92 applications. A frequency grid is a reference set of frequencies 93 used to denote allowed nominal central frequencies that may be used 94 for defining applications. The channel spacing is the frequency 95 spacing between two allowed nominal central frequencies. All of the 96 wavelengths on a fiber should use different central frequencies and 97 occupy a fixed bandwidth of frequency. 99 Fixed grid channel spacing is selected from 12.5 GHz, 25 GHz, 50 GHz, 100 100 GHz and integer multiples of 100 GHz. But [G.694.1] also 101 defines "flexible grids", also known as "flexi-grid". The terms 102 "frequency slot" (i.e., the frequency range allocated to a specific 103 channel and unavailable to other channels within a flexible grid) 104 and "slot width" (i.e., the full width of a frequency slot in a 105 flexible grid) are used to define a flexible grid. 107 [FLEX-FWK] defines a framework and the associated control plane 108 requirements for the GMPLS based control of flexi-grid DWDM networks. 110 [RFC6163] provides a framework for GMPLS and Path Computation 111 Element (PCE) control of Wavelength Switched Optical Networks 112 (WSONs), and [WSON-OSPF] defines the requirements and OSPF-TE 113 extensions in support of GMPLS control of a WSON. 115 [FLEX-SIG] describes requirements and protocol extensions for 116 signaling to set up LSPs in networks that support the flexi-grid, 117 and this document complements [FLEX-SIG] by describing the 118 requirement and extensions for OSPF-TE routing in a flexi-grid 119 network. 121 2. Terminology 123 For terminology related to flexi-grid, please consult [FLEX-FWK] and 124 [G.694.1]. 126 2.1. Conventions Used in this Document 128 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 129 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 130 document are to be interpreted as described in RFC-2119 [RFC2119]. 132 3. Requirements for Flexi-grid Routing 134 The architecture for establishing LSPs in a Spectrum Switched 135 optical Network (SSON) is described in [FLEX-FWK]. 137 A flexi-LSP occupies a specific frequency slot, i.e. a range of 138 frequencies. The process of computing a route and the allocation of 139 a frequency slot is referred to as RSA (Routing and Spectrum 140 Assignment). [FLEX-FWK] describes three types of architectural 141 approaches to RSA: combined RSA; separated RSA; and distributed SA. 142 The first two approaches among them could be called "centralized SA" 143 because both routing and spectrum (frequency slot) assignment are 144 performed by centralized entity before the signaling procedure. 146 In the case of centralized SA, the assigned frequency slot is 147 specified in the Path message during LSP setup. In the case of 148 distributed SA, the slot width of the flexi-grid LSP is specified in 149 the Path message, allowing the involved network elements to select 150 the frequency slot to be used. 152 If the capability of switching or converting the whole optical 153 spectrum allocated to an optical spectrum LSP is not available at 154 nodes along the path of the LSP, the LSP is subject to the Optical 155 "Spectrum Continuity Constraint", as described in [FLEX-FWK]. 157 The remainder of this section states the additional extensions on 158 the routing protocols in a flexi-grid network. That is, the 159 additional information that must be collected and passed between 160 nodes in the network by the routing protocols in order to enable 161 correct path computation and signaling in support of LSPs within the 162 network. 164 3.1. Available Frequency Ranges 166 In the case of flexi-grids, the central frequency steps from 193.1 167 THz with 6.25 GHz granularity. The calculation method of central 168 frequency and the frequency slot width of flexi-LSP are defined in 169 [G.694.1]. 171 On a DWDM link, the frequency slots must not overlap with each other. 172 However, the border frequencies of two frequency slots may be the 173 same frequency, i.e., the highest frequency of a frequency slot may 174 be the lowest frequency of the next frequency slot. 176 Frequency Slot 1 Frequency Slot 2 177 +-----------+-----------------------+ 178 | | | 179 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 180 ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... 181 ------------ ------------------------ 182 ^ ^ 183 Central F = 193.1THz Central F = 193.1375 THz 184 Slot width = 25 GHz Slot width = 50 GHz 186 Figure 1 - Two Frequency Slots on a Link 188 Figure 1 shows two adjacent frequency slots on a link. The highest 189 frequency of frequency slot 1 denoted by n=2 is the lowest frequency 190 of slot 2. In this example, it means that the frequency range from 191 n=-2 to n=10 is occupied and is unavailable to other flexi-LSPs. 193 Hence, in order to clearly show which LSPs can be supported and what 194 frequency slots are unavailable, the available frequency ranges 195 should be advertised by the routing protocol for the flexi-grid DWDM 196 links. A set of non-overlapping available frequency ranges should 197 be disseminated in order to allow efficient resource management of 198 flexi-grid DWDM links and RSA procedures which are described in 199 section 5.8 of [FLEX-FWK]. 201 3.2. Application Compliance Considerations 203 As described in [G.694.1], devices or applications that make use of 204 the flexi-grid may not be capable of supporting every possible slot 205 width or position (i.e., central frequency). In other words, 206 applications or implementations may be defined where only a subset 207 of the possible slot widths and positions are required to be 208 supported. 210 For example, an application could be defined where the nominal 211 central frequency granularity is 12.5 GHz (by only requiring values 212 of n that are even) and that only requires slot widths as a multiple 213 of 25 GHz (by only requiring values of m that are even). 215 Hence, in order to support all possible applications and 216 implementations the following information should be advertised for a 217 flexi-grid DWDM link: 219 o Central frequency granularity: a multiplier of 6.25 GHz. 221 o Slot width granularity: a multiplier of 12.5 GHz. 223 o Slot width range: two multipliers of 12.5GHz, each indicate the 224 minimal and maximal slot width supported by a port respectively. 226 The combination of slot width range and slot width granularity can 227 be used to determine the slot widths set supported by a port. 229 3.3. Comparison with Fixed-grid DWDM Links 231 In the case of fixed-grid DWDM links, each wavelength has a pre- 232 defined central frequency and each wavelength has the same frequency 233 range (i.e., there is a uniform channel spacing). Hence all the 234 wavelengths on a DWDM link can be identified uniquely simply by 235 giving it an identifier (such as the central wavelength [RFC6205]), 236 and the status of the wavelengths (available or not) can be 237 advertised through a routing protocol. 239 Figure 2 shows a link that supports a fixed-grid with 50 GHz channel 240 spacing. The central frequencies of the wavelengths are pre-defined 241 by values of 'n' and each wavelength occupies a fixed 50 GHz 242 frequency range as described in [G.694.1]. 244 W(-2) | W(-1) | W(0) | W(1) | W(2) | 245 ...---------+-----------+-----------+-----------+-----------+----... 246 | 50 GHz | 50 GHz | 50 GHz | 50 GHz | 248 n=-2 n=-1 n=0 n=1 n=2 249 ...---+-----------+-----------+-----------+-----------+----------... 250 ^ 251 Central F = 193.1THz 253 Figure 2 - A Link Supports Fixed Wavelengths with 50 GHz Channel 254 Spacing 256 Unlike the fixed-grid DWDM links, on a flexi-grid DWDM link the slot 257 width of the frequency slot are flexible as described in section 3.1. 258 That is, the value of m in the formula is uncertain before a 259 frequency slot is actually allocated. For this reason, the 260 available frequency slot/ranges need to be advertised for a flexi- 261 grid DWDM link instead of the specific "wavelengths" that are 262 sufficient for a fixed-grid link. 264 4. Extensions 266 As described in [FLEX-FWK], the network connectivity topology 267 constructed by the links/nodes and node capabilities are the same as 268 for WSON, and can be advertised by the GMPLS routing protocols 269 (refer to section 6.2 of [RFC6163]). In the flexi-grid case, the 270 available frequency ranges instead of the specific "wavelengths" are 271 advertised for the link. This section defines the GMPLS OSPF-TE 272 extensions in support of advertising the available frequency ranges 273 for flexi-grid DWDM links. 275 4.1. ISCD for Flexi-grid 277 Value Type 278 ----- ---- 279 152 (TBA by IANA) Flexi-Grid-LSC capable (DWDM-LSC) 280 Switching Capability and Encoding values MUST be used as follows: 282 Switching Capability = Flexi-Grid-LSC 284 Encoding Type = lambda [as defined in RFC3471] 286 When Switching Capability and Encoding fields are set to values 287 as stated above, the Interface Switching Capability Descriptor MUST 288 be interpreted as in RFC4203 with the optional inclusion of one or 289 more Switching Capability Specific Information sub-TLVs. 291 4.2. Available Labels Set Sub-TLV 293 As described in section 3.1, the available frequency ranges other 294 than the available frequency slots should be advertised for the 295 flexi-grid DWDM links. The label encoding defined in [FLEX-LBL] is 296 used to encode the label field in Available Labels Set sub-TLV [GEN- 297 Encode]. 299 4.2.1. Inclusive/Exclusive Label Range 301 The inclusive/exclusive label ranges format of the Available Labels 302 Set sub-TLV defined in [GEN-ENCODE] can be used for specifying the 303 frequency ranges of the flexi-grid DWDM links. 305 Note that multiple Available Labels Set sub-TLVs may be needed if 306 there are multiple discontinuous frequency ranges on a link. 308 4.2.2. Inclusive/Exclusive Label Lists 310 The inclusive/exclusive label lists format of Available Labels Set 311 sub-TLV defined in [GEN-ENCODE] can be used for specifying the 312 available central frequencies of flexi-grid DWDM links. 314 4.2.3. Bitmap 316 The bitmap format of Available Labels Set sub-TLV defined in [GEN- 317 ENCODE] can be used for specifying the available central frequencies 318 of the flexi-grid DWDM links. 320 Each bit in the bit map represents a particular central frequency 321 with a value of 1/0 indicating whether the central frequency is in 322 the set or not. Bit position zero represents the lowest central 323 frequency and corresponds to the base label, while each succeeding 324 bit position represents the next central frequency logically above 325 the previous. 327 4.3. Extensions to Port Label Restriction sub-TLV 329 As described in Section 3.2, a port that supports flexi-grid may 330 support only a restricted subset of the full flexible grid. The 331 Port Label Restriction sub-TLV is defined in [GEN-ENCODE] and [GEN- 332 OSPF]. It can be used to describe the label restrictions on a port. 333 A new restriction type, the flexi-grid Restriction Type, is defined 334 here to specify the restrictions on a port to support flexi-grid. 336 0 1 2 3 337 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 1 338 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 339 | MatrixID | RstType = TBA | Reserved | 340 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 341 | C.F.G | S.W.G | Min Width | Max Width | 342 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 344 MatrixID (8 bits): As defined in [GEN-ENCODE]. 346 RstType (Restriction Type, 8 bits): Takes the value (TBD) to 347 indicate the restrictions on a port to support flexi-grid. 349 C.F.G (Central Frequency Granularity, 8 bits): A positive integer. 350 Its value indicates the multiple of 6.25 GHz in terms of central 351 frequency granularity. 353 S.W.G (Slot Width Granularity, 8 bits): A positive integer. Its 354 value indicates the multiple of 12.5 GHz in terms of slot width 355 granularity. 357 Min Width (8 bits): A positive integer. Its value indicates the 358 multiple of 12.5 GHz in terms of the supported minimal slot width. 360 Max Width (8 bits): A positive integer. Its value indicates the 361 multiple of 12.5 GHz in terms of the supported maximal slot width. 363 4.4. Examples for Available Label Set Sub-TLV 365 Figure 3 shows an example of available frequency range of a flexi- 366 grid DWDM link. 368 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 369 ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... 370 |--Available Frequency Range--| 372 Figure 3 - Flexi-grid DWDM Link 374 The symbol '+' represents the allowed nominal central frequency. The 375 symbol "--" represents a 6.25 GHz frequency unit. The number on the 376 top of the line represents the 'n' in the frequency calculation 377 formula (193.1 + n * 0.00625). The nominal central frequency is 378 193.1 THz when n equals zero. 380 Assume that the central frequency granularity is 6.25GHz, the label 381 set can be encoded as follows: 383 Inclusive Label Range: 385 o Start Slot = -2; 386 o End Slot = 8. 388 The available central frequencies (-1, 0, 1, 2, 3, 4, 5, 6, 7) can 389 be deduced by the Inclusive Label Range, because the Central 390 Frequency Granularity is 6.25 GHz. 392 Inclusive Label Lists: 394 o List Entry 1 = slot -1; 395 o List Entry 2 = slot 0; 396 o List Entry 3 = slot 1; 397 o List Entry 4 = slot 2; 398 o List Entry 5 = slot 3; 399 o List Entry 6 = slot 4; 400 o List Entry 7 = slot 5; 401 o List Entry 8 = slot 6; 402 o List Entry 9 = slot 7. 404 Bitmap: 406 o Base Slot = -1; 407 o Bitmap = 111111111(padded out to a full multiple of 32 bits) 409 5. IANA Considerations 411 [GEN-OSPF] defines the Port label Restriction sub-TLV of OSPF TE 412 Link TLV. It also creates a registry of values of the Restriction 413 Type field of that sub-TLV 415 IANA is requested to assign a new value from that registry as 416 follows: 418 Value Meaning Reference 420 TBD Flexi-grid restriction [This.I-D] 422 6. Implementation Status 424 [RFC Editor Note: Please remove this entire seciton prior to 425 publication as an RFC.] 427 This section records the status of known implementations of the 428 protocol defined by this specification at the time of posting of 429 this Internet-Draft, and is based on a proposal described in RFC 430 6982[RFC6982]. The description of implementations in this section 431 is intended to assist the IETF in its decision processes in 432 progressing drafts to RFCs. Please note that the listing of any 433 individual implementation here does not imply endorsement by the 434 IETF. Furthermore, no effort has been spent to verify the 435 information presented here that was supplied by IETF contributors. 436 This is not intended as, and must not be construed to be, a catalog 437 of available implementations or their features. Readers are advised 438 to note that other implementations may exist. 440 According to RFC 6982, "this will allow reviewers and working groups 441 to assign due consideration to documents that have the benefit of 442 running code, which may serve as evidence of valuable 443 experimentation and feedback that have made the implemented 444 protocols more mature. It is up to the individual working groups to 445 use this information as they see fit. 447 6.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC) 449 Organization Responsible for the Implementation: CTTC - Centre 450 Tecnologic de Telecomunicacions de Catalunya (CTTC), Optical 451 Networks and Systems Department, http://wikiona.cttc.es. 453 Implementation Name and Details: ADRENALINE testbed, 454 http://networks.cttc.es/experimental-testbeds/ 456 Brief Description: Experimental testbed implementation of 457 GMPLS/PCE control plane. 459 Level of Maturity: Implemented as extensions to a mature 460 GMLPS/PCE control plane. It is limited to research / prototyping 461 stages but it has been used successfully for more than the last five 462 years. 464 Coverage: Support for the 64 bit label [FLEX-LBL] for flexi-grid 465 as described in this document, with available label set encoded as 466 bitmap. It is expected that this implementation will evolve to follow the 467 evolution of this document. 469 Licensing: Proprietary 471 Implementation Experience: Implementation of this document 472 reports no issues. General implementation experience has been 473 reported in a number of journal papers. Contact Ramon Casellas for 474 more information or see http://networks.cttc.es/publications/? 475 search=GMPLS&research_area=optical-networks-systems 477 Contact Information: Ramon Casellas: ramon.casellas@cttc.es 479 Interoperability: No report. 481 7. Acknowledgments 483 This work was supported in part by the FP-7 IDEALIST project under 484 grant agreement number 317999. 486 8. Security Considerations 488 This document does not introduce any further security issues other 489 than those discussed in [RFC3630], [RFC4203]. 491 9. References 493 9.1. Normative References 495 [RFC2119] S. Bradner, "Key words for use in RFCs to indicate 496 requirements levels", RFC 2119, March 1997. 498 [G.694.1] ITU-T Recommendation G.694.1 (revision 2), "Spectral grids 499 for WDM applications: DWDM frequency grid", February 2012. 501 [GEN-ENCODE] Bernstein, G., Lee, Y., Li, D., and W. Imajuku, 502 "General Network Element Constraint Encoding for GMPLS 503 Controlled Networks", draft-ietf-ccamp-general-constraint- 504 encode, work in progress. 506 [GEN-OSPF] Fatai Zhang, Y. Lee, Jianrui Han, G. Bernstein and Yunbin 507 Xu, " OSPF-TE Extensions for General Network Element 508 Constraints ", draft-ietf-ccamp-gmpls-general-constraints- 509 ospf-te, work in progress. 511 [RFC6205] T. Otani and D. Li, "Generalized Labels for Lambda-Switch- 512 Capable (LSC) Label Switching Routers", RFC 6205, March 513 2011. 515 [FLEX-LBL] King, D., Farrel, A. and Y. Li, "Generalized Labels for 516 the Flexi-Grid in Lambda Switch Capable (LSC) Label 517 Switching Routers", draft-farrkingel-ccamp-flexigrid- 518 lambda-label, work in progress. 520 9.2. Informative References 522 [RFC6163] Y. Lee, G. Bernstein and W. Imajuku, "Framework for GMPLS 523 and Path Computation Element (PCE) Control of Wavelength 524 Switched Optical Networks (WSONs)", RFC 6163, April 2011. 526 [FLEX-SIG] F.Zhang et al, "RSVP-TE Signaling Extensions in support 527 of Flexible-grid", draft-zhang-ccamp-flexible-grid-rsvp- 528 te-ext, work in progress. 530 [FLEX-FWK] Gonzalez de Dios, O,, Casellas R., Zhang, F., Fu, X., 531 Ceccarelli, D., and I. Hussain, ''Framework and 532 Requirements for GMPLS based control of Flexi-grid DWDM 533 networks', draft-ogrcetal-cammp-flexi-grid-fwk, work in 534 progress. 536 [WSON-OSPF] Y. Lee and G. Bernstein, "GMPLS OSPF Enhancement for 537 Signal and Network Element Compatibility for Wavelength 538 Switched Optical Networks ", draft-ietf-ccamp-wson-signal- 539 compatibility-ospf, work in progress. 541 10. Authors' Addresses 543 Xian Zhang 544 Huawei Technologies 545 Email: zhang.xian@huawei.com 547 Haomian Zheng 548 Huawei Technologies 549 Email: zhenghaomian@huawei.com 551 Ramon Casellas, Ph.D. 552 CTTC 553 Spain 554 Phone: +34 936452916 555 Email: ramon.casellas@cttc.es 557 Oscar Gonzalez de Dios 558 Telefonica Investigacion y Desarrollo 559 Emilio Vargas 6 560 Madrid, 28045 561 Spain 562 Phone: +34 913374013 563 Email: ogondio@tid.es 565 Daniele Ceccarelli 566 Ericsson 567 Via A. Negrone 1/A 568 Genova - Sestri Ponente 569 Italy 570 Email: daniele.ceccarelli@ericsson.com 572 11. Contributors' Addresses 574 Adrian Farrel 575 Old Dog Consulting 576 Email: adrian@olddog.co.uk 578 Fatai Zhang 579 Huawei Technologies 580 Email: zhangfatai@huawei.com 582 Lei Wang, 583 ZTE 584 Email: wang.lei31@zte.com.cn