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'RFC4203' on line 405 looks like a reference Summary: 4 errors (**), 0 flaws (~~), 5 warnings (==), 13 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group Fatai Zhang 2 Internet-Draft Xian Zhang 3 Intended status: Informational Huawei 4 Ramon Casellas 5 CTTC 6 O. Gonzalez de Dios 7 Telefonica 8 D. Ceccarelli 9 Ericsson 10 Expires: December 28, 2013 June 29, 2013 12 GMPLS OSPF-TE Extensions in support of Flexible Grid DWDM Networks 14 draft-zhang-ccamp-flexible-grid-ospf-ext-02.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 December 28, 2013. 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 ...................5 69 4. Extensions .................................................. 6 70 4.1. Available Labels Set Sub-TLV............................ 6 71 4.1.1. Inclusive/Exclusive Label Range ....................7 72 4.1.2. Inclusive/Exclusive Label Lists ....................7 73 4.1.3. Bitmap ............................................ 7 74 4.2. Extensions to Port Label Restriction sub-TLV ............7 75 4.3. Examples for Available Label Set Sub-TLV ................8 76 5. IANA Considerations ......................................... 9 77 6. Security Considerations...................................... 9 78 7. References ................................................. 10 79 7.1. Normative References................................... 10 80 7.2. Informative References................................. 10 81 8. Authors' Addresses ..........................................11 82 9. Contributors' Addresses..................................... 11 84 1. Introduction 86 [G.694.1] defines the Dense Wavelength Division Multiplexing (DWDM) 87 frequency grids for Wavelength Division Multiplexing (WDM) 88 applications. A frequency grid is a reference set of frequencies 89 used to denote allowed nominal central frequencies that may be used 90 for defining applications. The channel spacing is the frequency 91 spacing between two allowed nominal central frequencies. All of the 92 wavelengths on a fiber should use different central frequencies and 93 occupy a fixed bandwidth of frequency. 95 Fixed grid channel spacing is selected from 12.5 GHz, 25 GHz, 50 GHz, 96 100 GHz and integer multiples of 100 GHz. But [G.694.1] also 97 defines "flexible grids", also known as "flexi-grid". The terms 98 "frequency slot" (i.e., the frequency range allocated to a specific 99 channel and unavailable to other channels within a flexible grid) 100 and "slot width" (i.e., the full width of a frequency slot in a 101 flexible grid) are used to define a flexible grid. 103 [FLEX-FWK] defines a framework and the associated control plane 104 requirements for the GMPLS based control of flexi-grid DWDM networks. 106 [RFC6163] provides a framework for GMPLS and Path Computation 107 Element (PCE) control of Wavelength Switched Optical Networks 108 (WSONs), and [WSON-OSPF] defines the requirements and OSPF-TE 109 extensions in support of GMPLS control of a WSON. 111 [FLEX-SIG] describes requirements and protocol extensions for 112 signaling to set up LSPs in networks that support the flexi-grid, 113 and this document complements [FLEX-SIG] by describing the 114 requirement and extensions for OSPF-TE routing in a flexi-grid 115 network. 117 2. Terminology 119 For terminology related to flexi-grid, please consult [FLEX-FWK] and 120 [G.694.1]. 122 2.1. Conventions Used in this Document 124 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 125 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 126 document are to be interpreted as described in RFC-2119 [RFC2119]. 128 3. Requirements for Flexi-grid Routing 130 The architecture for establishing LSPs in a Spectrum Switched 131 optical Network (SSON) is described in [FLEX-FWK]. 133 An flexi-LSP occupies a specific frequency slot, i.e. a range of 134 frequencies. The process of computing a route and the allocation of 135 a frequency slot is referred to as RSA (Routing and Spectrum 136 Assignment). [FLEX-FWK] describes three types of architectural 137 approaches to RSA: combined RSA; separated RSA; and distributed SA. 138 The first two approaches among them could be called "centralized SA" 139 because both routing and spectrum (frequency slot) assignment are 140 performed by centralized entity before the signaling procedure. 142 In the case of centralized SA, the assigned frequency slot is 143 specified in the Path message during LSP setup. In the case of 144 distributed SA, the slot width of the flexi-grid LSP is specified in 145 the Path message, allowing the involved network elements to select 146 the frequency slot to be used. 148 If the capability of switching or converting the whole optical 149 spectrum allocated to an optical spectrum LSP is not available at 150 nodes along the path of the LSP, the LSP is subject to the Optical 151 "Spectrum Continuity Constraint", as described in [FLEX-FWK]. 153 The remainder of this section states the additional extensions on 154 the routing protocols in a flexi-grid network. That is, the 155 additional information that must be collected and passed between 156 nodes in the network by the routing protocols in order to enable 157 correct path computation and signaling in support of LSPs within the 158 network. 160 3.1. Available Frequency Ranges 162 In the case of flexi-grids, the central frequency steps from 193.1 163 THz with 6.25 GHz granularity. The calculation method of central 164 frequency and the frequency slot width of flexi-LSP are defined in 165 [G.694.1]. 167 On a DWDM link, the frequency slots must not overlap with each other. 168 However, the border frequencies of two frequency slots may be the 169 same frequency, i.e., the highest frequency of a frequency slot may 170 be the lowest frequency of the next frequency slot. 172 Frequency Slot 1 Frequency Slot 2 173 +-----------+-----------------------+ 174 | | | 175 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 176 ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... 177 ------------ ------------------------ 178 ^ ^ 179 Central F = 193.1THz Central F = 193.1375 THz 180 Slot width = 25 GHz Slot width = 50 GHz 182 Figure 1 - Two Frequency Slots on a Link 184 Figure 1 shows two adjacent frequency slots on a link. The highest 185 frequency of frequency slot 1 denoted by n=2 is the lowest frequency 186 of slot 2. In this example, it means that the frequency range from 187 n=-2 to n=10 is occupied and is unavailable to other flexi-LSPs. 189 Hence, in order to clearly show which LSPs can be supported and what 190 frequency slots are unavailable, the available frequency ranges 191 should be advertised by the routing protocol for the flexi-grid DWDM 192 links. A set of non-overlapping available frequency ranges should 193 be disseminated in order to allow efficient resource management of 194 flexi-grid DWDM links and RSA procedures which are described in 195 section 5.7 of [FLEX-FWK]. 197 3.2. Application Compliance Considerations 199 As described in [G.694.1], devices or applications that make use of 200 the flexi-grid may not be capable of supporting every possible slot 201 width or position (i.e., central frequency). In other words, 202 applications or implementations may be defined where only a subset 203 of the possible slot widths and positions are required to be 204 supported. 206 For example, an application could be defined where the nominal 207 central frequency granularity is 12.5 GHz (by only requiring values 208 of n that are even) and that only requires slot widths as a multiple 209 of 25 GHz (by only requiring values of m that are even). 211 Hence, in order to support all possible applications and 212 implementations the following information should be advertised for a 213 flexi-grid DWDM link: 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 range: two multipliers of 12.5GHz, each indicate the 220 minimal and maximal slot width supported by a port respectively. 222 The combination of slot width range and slot width granularity can 223 be used to determine the slot widths set supported by a port. 225 3.3. Comparison with Fixed-grid DWDM Links 227 In the case of fixed-grid DWDM links, each wavelength has a pre- 228 defined central frequency and each wavelength has the same frequency 229 range (i.e., there is a uniform channel spacing). Hence all the 230 wavelengths on a DWDM link can be identified uniquely simply by 231 giving it an identifier (such as the central wavelength [RFC6205]), 232 and the status of the wavelengths (available or not) can be 233 advertised through a routing protocol. 235 Figure 2 shows a link that supports a fixed-grid with 50 GHz channel 236 spacing. The central frequencies of the wavelengths are pre-defined 237 by values of 'n' and each wavelength occupies a fixed 50 GHz 238 frequency range as described in [G.694.1]. 240 W(-2) | W(-1) | W(0) | W(1) | W(2) | 241 ...---------+-----------+-----------+-----------+-----------+----... 242 | 50 GHz | 50 GHz | 50 GHz | 50 GHz | 244 n=-2 n=-1 n=0 n=1 n=2 245 ...---+-----------+-----------+-----------+-----------+----------... 246 ^ 247 Central F = 193.1THz 249 Figure 2 - A Link Supports Fixed Wavelengths with 50 GHz Channel 250 Spacing 252 Unlike the fixed-grid DWDM links, on a flexi-grid DWDM link the slot 253 width of the frequency slot are flexible as described in section 2.1. 254 That is, the value of m in the formula is uncertain before a 255 frequency slot is actually allocated. For this reason, the 256 available frequency slot/ranges need to be advertised for a flexi- 257 grid DWDM link instead of the specific "wavelengths" that are 258 sufficient for a fixed-grid link. 260 4. Extensions 262 As described in [FLEX-FWK], the network connectivity topology 263 constructed by the links/nodes and node capabilities are the same as 264 for WSON, and can be advertised by the GMPLS routing protocols 265 (refer to section 6.2 of [RFC6163]). In the flexi-grid case, the 266 available frequency ranges instead of the specific "wavelengths" are 267 advertised for the link. This section defines the GMPLS OSPF-TE 268 extensions in support of advertising the available frequency ranges 269 for flexi-grid DWDM links. 271 4.1. Available Labels Set Sub-TLV 273 As described in section 3.1, the available frequency ranges other 274 than the available frequency slots should be advertised for the 275 flexi-grid DWDM links. The label encoding defined in [FLEX-LBL] is 276 used to encode the label field in Available Labels Set sub-TLV [GEN- 277 Encode]. 279 4.1.1. Inclusive/Exclusive Label Range 281 The inclusive/exclusive label ranges format of the Available Labels 282 Set sub-TLV defined in [GEN-ENCODE] can be used for specifying the 283 frequency ranges of the flexi-grid DWDM links. 285 Note that multiple Available Labels Set sub-TLVs may be needed if 286 there are multiple discontinuous frequency ranges on a link. 288 4.1.2. Inclusive/Exclusive Label Lists 290 The inclusive/exclusive label lists format of Available Labels Set 291 sub-TLV defined in [GEN-ENCODE] can be used for specifying the 292 available central frequencies of flexi-grid DWDM links. 294 4.1.3. Bitmap 296 The bitmap format of Available Labels Set sub-TLV defined in [GEN- 297 ENCODE] can be used for specifying the available central frequencies 298 of the flexi-grid DWDM links. 300 Each bit in the bit map represents a particular central frequency 301 with a value of 1/0 indicating whether the central frequency is in 302 the set or not. Bit position zero represents the lowest central 303 frequency and corresponds to the base label, while each succeeding 304 bit position represents the next central frequency logically above 305 the previous. 307 4.2. Extensions to Port Label Restriction sub-TLV 309 As described in Section 3.2, a port that supports flexi-grid may 310 support only a restricted subset of the full flexible grid. The 311 Port Label Restriction sub-TLV is defined in [GEN-ENCODE] and [GEN- 312 OSPF]. It can be used to describe the label restrictions on a port. 313 A new restriction type, the flexi-grid Restriction Type, is defined 314 here to specify the restrictions on a port to support flexi-grid. 316 0 1 2 3 317 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 1 318 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 319 | MatrixID | RstType = TBA | Reserved | 320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 321 | C.F.G | S.W.G | Min Width | Max Width | 322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 MatrixID (8 bits): As defined in [GEN-ENCODE]. 326 RstType (Restriction Type, 8 bits): Takes the value (TBD) to 327 indicate the restrictions on a port to support flexi-grid. 329 C.F.G (Central Frequency Granularity, 8 bits): A positive integer. 330 Its value indicates the multiple of 6.25 GHz in terms of central 331 frequency granularity. 333 S.W.G (Slot Width Granularity, 8 bits): A positive integer. Its 334 value indicates the multiple of 12.5 GHz in terms of slot width 335 granularity. 337 Min Width (8 bits): A positive integer. Its value indicates the 338 multiple of 12.5 GHz in terms of the supported minimal slot width. 340 Max Width (8 bits): A positive integer. Its value indicates the 341 multiple of 12.5 GHz in terms of the supported maximal slot width. 343 4.3. Examples for Available Label Set Sub-TLV 345 Figure 3 shows an example of available frequency range of a flexi- 346 grid DWDM link. 348 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 349 ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... 350 |--Available Frequency Range--| 352 Figure 3 - Flexi-grid DWDM Link 354 The symbol '+' represents the allowed nominal central frequency. The 355 symbol "--" represents a 6.25 GHz frequency unit. The number on the 356 top of the line represents the 'n' in the frequency calculation 357 formula (193.1 + n * 0.00625). The nominal central frequency is 358 193.1 THz when n equals zero. 360 Assume that the central frequency granularity is 6.25GHz, the label 361 set can be encoded as follows: 363 Inclusive Label Range: 365 o Start Slot = -2; 366 o End Slot = 8. 368 The available central frequencies (-1, 0, 1, 2, 3, 4, 5, 6, 7) can 369 be deduced by the Inclusive Label Range, because the Central 370 Frequency Granularity is 6.25 GHz. 372 Inclusive Label Lists: 374 o List Entry 1 = slot -1; 375 o List Entry 2 = slot 0; 376 o List Entry 3 = slot 1; 377 o List Entry 4 = slot 2; 378 o List Entry 5 = slot 3; 379 o List Entry 6 = slot 4; 380 o List Entry 7 = slot 5; 381 o List Entry 8 = slot 6; 382 o List Entry 9 = slot 7. 384 Bitmap: 386 o Base Slot = -1; 387 o Bitmap = 111111111(padded out to a full multiple of 32 bits) 389 5. IANA Considerations 391 [GEN-OSPF] defines the Port label Restriction sub-TLV of OSPF TE 392 Link TLV. It also creates a registry of values of the Restriction 393 Type field of that sub-TLV 395 IANA is requested to assign a new value from that registry as 396 follows: 398 Value Meaning Reference 400 TBD Flexi-grid restriction [This.I-D] 402 6. Security Considerations 404 This document does not introduce any further security issues other 405 than those discussed in [RFC3630], [RFC4203]. 407 7. References 409 7.1. Normative References 411 [RFC2119] S. Bradner, "Key words for use in RFCs to indicate 412 requirements levels", RFC 2119, March 1997. 414 [G.694.1] ITU-T Recommendation G.694.1 (revision 2), "Spectral grids 415 for WDM applications: DWDM frequency grid", February 2012. 417 [GEN-ENCODE] Bernstein, G., Lee, Y., Li, D., and W. Imajuku, 418 "General Network Element Constraint Encoding for GMPLS 419 Controlled Networks", draft-ietf-ccamp-general-constraint- 420 encode, work in progress. 422 [GEN-OSPF] Fatai Zhang, Y. Lee, Jianrui Han, G. Bernstein and Yunbin 423 Xu, " OSPF-TE Extensions for General Network Element 424 Constraints ", draft-ietf-ccamp-gmpls-general-constraints- 425 ospf-te, work in progress. 427 [RFC6205] T. Otani and D. Li, "Generalized Labels for Lambda-Switch- 428 Capable (LSC) Label Switching Routers", RFC 6205, March 429 2011. 431 [FLEX-LBL] King, D., Farrel, A. and Y. Li, "Generalized Labels for 432 the Flexi-Grid in Lambda Switch Capable (LSC) Label 433 Switching Routers", draft-farrkingel-ccamp-flexigrid- 434 lambda-label, work in progress. 436 7.2. Informative References 438 [RFC6163] Y. Lee, G. Bernstein and W. Imajuku, "Framework for GMPLS 439 and Path Computation Element (PCE) Control of Wavelength 440 Switched Optical Networks (WSONs)", RFC 6163, April 2011. 442 [FLEX-SIG] F.Zhang et al, "RSVP-TE Signaling Extensions in support 443 of Flexible-grid", draft-zhang-ccamp-flexible-grid-rsvp- 444 te-ext, work in progress. 446 [FLEX-FWK] Gonzalez de Dios, O,, Casellas R., Zhang, F., Fu, X., 447 Ceccarelli, D., and I. Hussain, "Framework and 448 Requirements for GMPLS based control of Flexi-grid DWDM 449 networks', draft-ogrcetal-cammp-flexi-grid-fwk, work in 450 progress. 452 [WSON-OSPF] Y. Lee and G. Bernstein, "GMPLS OSPF Enhancement for 453 Signal and Network Element Compatibility for Wavelength 454 Switched Optical Networks ", draft-ietf-ccamp-wson-signal- 455 compatibility-ospf, work in progress. 457 8. Authors' Addresses 459 Fatai Zhang 460 Huawei Technologies 461 Email: zhangfatai@huawei.com 463 Xian Zhang 464 Huawei Technologies 465 Email: zhang.xian@huawei.com 467 Ramon Casellas, Ph.D. 468 CTTC 469 Spain 470 Phone: +34 936452916 471 Email: ramon.casellas@cttc.es 473 Oscar Gonzalez de Dios 474 Telefonica Investigacion y Desarrollo 475 Emilio Vargas 6 476 Madrid, 28045 477 Spain 478 Phone: +34 913374013 479 Email: ogondio@tid.es 481 Daniele Ceccarelli 482 Ericsson 483 Via A. Negrone 1/A 484 Genova - Sestri Ponente 485 Italy 486 Email: daniele.ceccarelli@ericsson.com 488 9. Contributors' Addresses 490 Adrian Farrel 491 Old Dog Consulting 492 Email: adrian@olddog.co.uk