idnits 2.17.1 draft-xihua-ccamp-wson-link-bundle-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** The document seems to lack a License Notice according IETF Trust Provisions of 28 Dec 2009, Section 6.b.ii or Provisions of 12 Sep 2009 Section 6.b -- however, there's a paragraph with a matching beginning. Boilerplate error? (You're using the IETF Trust Provisions' Section 6.b License Notice from 12 Feb 2009 rather than one of the newer Notices. See https://trustee.ietf.org/license-info/.) Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([RFC4201]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. ** The document seems to lack a both a reference to RFC 2119 and the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords. RFC 2119 keyword, line 643: '...the bundled link MUST not be advertise...' Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: If one of the component links goes down, the associated bundled link remains up and continues to be advertised, provided that at least one component link associated with the bundled link is up. The available wavelength of the component link that is down is set to zero, and wavelengths availability information of the bundle must be recomputed. If all the component links associated with a given bundled link are down, the bundled link MUST not be advertised into OSPF/IS-IS in terms of [RFC4201]. -- The document date (March 3, 2009) is 5526 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Missing Reference: 'RFC4201' is mentioned on line 644, but not defined == Missing Reference: 'RFC5212' is mentioned on line 813, but not defined == Missing Reference: 'WSON-SIGNALING' is mentioned on line 710, but not defined == Missing Reference: 'RFC4420' is mentioned on line 711, but not defined ** Obsolete undefined reference: RFC 4420 (Obsoleted by RFC 5420) Summary: 4 errors (**), 0 flaws (~~), 6 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group X. Fu, Ed. 3 Internet-Draft ZTE Corporation 4 Intended status: Informational March 3, 2009 5 Expires: September 4, 2009 7 Link Bundle in Wavelength Switched Optical Networks 8 draft-xihua-ccamp-wson-link-bundle-01 10 Status of this Memo 12 This Internet-Draft is submitted to IETF in full conformance with the 13 provisions of BCP 78 and BCP 79. 15 Internet-Drafts are working documents of the Internet Engineering 16 Task Force (IETF), its areas, and its working groups. Note that 17 other groups may also distribute working documents as Internet- 18 Drafts. 20 Internet-Drafts are draft documents valid for a maximum of six months 21 and may be updated, replaced, or obsoleted by other documents at any 22 time. It is inappropriate to use Internet-Drafts as reference 23 material or to cite them other than as "work in progress." 25 The list of current Internet-Drafts can be accessed at 26 http://www.ietf.org/ietf/1id-abstracts.txt. 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 This Internet-Draft will expire on September 4, 2009. 33 Copyright Notice 35 Copyright (c) 2009 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents in effect on the date of 40 publication of this document (http://trustee.ietf.org/license-info). 41 Please review these documents carefully, as they describe your rights 42 and restrictions with respect to this document. 44 Abstract 46 [RFC4201] provides a link bundle mechanism to improve routing 47 scalability by reducing the amount of information that has to be 48 handled by IGP (OSPF and/or IS-IS). This reduction is accomplished 49 by performing information aggregation/abstraction. 51 As with any other information aggregation/abstraction, this results 52 in losing some of important information. In WSON and MRN, this lost 53 information is very important for the path computation entity to 54 calculate an accurate path. This document discusses some 55 requirements of link bundle for the new GMPLS networks (e.g., WSON 56 and MRN). The draft gives some routing and signaling analysis for 57 this issue. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 2. Link Bundling of WSON . . . . . . . . . . . . . . . . . . . . 4 63 2.1. Restrictions on WSON Bundling . . . . . . . . . . . . . . 4 64 2.2. Connectivity Constraint Information and Wavelength 65 Conversion Capability/Availability of a WSON Node . . . . 5 66 2.3. Available Wavelength and Wavelength Constraint 67 Information of a Link . . . . . . . . . . . . . . . . . . 9 68 2.3.1. Routing Consideration . . . . . . . . . . . . . . . . 12 69 2.3.1.1. Wavelengths Constraint Information of Bundled 70 Link . . . . . . . . . . . . . . . . . . . . . . . 12 71 2.3.1.2. Wavelengths Availability Information of 72 Bundled Link . . . . . . . . . . . . . . . . . . . 13 73 2.3.2. Other Consideration . . . . . . . . . . . . . . . . . 14 74 2.4. Bidirectional Path Using Same Component Link and 75 Wavelength on Both Directions . . . . . . . . . . . . . . 14 76 2.4.1. Centralized Component Link Selection . . . . . . . . . 15 77 2.4.2. Distributed Component Link Selection . . . . . . . . . 15 78 2.4.2.1. Centralized Wavelength Assignment . . . . . . . . 16 79 2.4.2.2. Distributed Wavelength Assignment . . . . . . . . 16 80 3. Link Bundling of Multi-Region Network . . . . . . . . . . . . 18 81 4. Security Considerations . . . . . . . . . . . . . . . . . . . 18 82 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 83 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 84 7. Normative References . . . . . . . . . . . . . . . . . . . . . 18 85 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 19 87 1. Introduction 89 In the general case of limited or no wavelength conversion in WSON, 90 available wavelength information/wavelength constraint information of 91 a link and connectivity constraint information/wavelength conversion 92 capability/availability information of a node is essential to perform 93 efficient and accurate path computation. [WSON-FRAME] provides 94 control plane models for key wavelength switched optical network 95 subsystems and processes. [WSON-INFO] provides efficient encodings 96 of information needed by RWA process in WSON and extends GMPLS IGP. 97 If the wavelengths availability information is not known by the 98 entities performing the path computation, then wavelength assignment 99 must be done locally by the nodes on hop-by-hop to negotiate label 100 selection. However, this case can easily lead to blocking problems. 102 [RFC4201] provides a link bundle mechanism to improve routing 103 scalability by reducing the amount of information that has to be 104 handled by IGP (OSPF and/or IS-IS). This reduction is accomplished 105 by performing information aggregation/abstraction. As with any other 106 information aggregation/abstraction, this results in losing some 107 important information. 109 In MRN/MLN, Adjustment Capacity refers to the property of a hybrid 110 node to interconnect different switching capabilities it provides 111 through its external interfaces [RFC5212]. This information allows 112 path computation to select an end-to-end multi-region path that 113 includes links of different switching capabilities that are joined by 114 LSRs that can adapt the signal between the links. If link bundling 115 is done, then the adjustment capacity information may be also lost 116 with current GMPLS routing. 118 [WSON-SIGNALING] provides some scenarios where the same wavelength on 119 each link along a unidirectional path and the same wavelength on both 120 directions of each link along a bidirectional path should be 121 reserved. Base on the requirement of carriers for simplified 122 management to reduce the OPEX, they also would like to create an end- 123 to-end path that uses the same wavelength and the same component 124 links on both directions of each bundled link. At the same time, 125 with limited or no wavelength conversion, sometimes the wavelength 126 could not be available on the same component link on both directions. 127 It may actually be the case that the lambda is only available in one 128 direction on one component link, and the other direction is only 129 available on a different component link. So it may fail to select 130 the same component on both directions in a bundled link to meet this 131 requirement. 133 Using the same component link on both directions of a bundled link is 134 sometimes required to control not only WSON but also other switching 135 capability network. How to select the component link could be the 136 default policy of a node, but different nodes may apply different 137 policies in the interoperability environment. So each node should be 138 explicitly notified of this requirement to select the same component 139 link on both directions on a bundled link. 141 This document discusses the problem when we apply link bundle 142 technology to WSON and provides corresponding solutions. This 143 document is currently limited to consideration of bundled link 144 without optical impairment in WSON. Optical impairment on bundled 145 links is for future consideration. When link bundle is applied on 146 multiple switching capability network (e.g., MRN/MLN), the issue is 147 further for consideration. 149 2. Link Bundling of WSON 151 After Link Bundle is applied to WSON, much important information will 152 be lost. The case where several TE links are advertised for one TE 153 Link without link bundling is further for study. 155 2.1. Restrictions on WSON Bundling 157 In term of [RFC4201], all component links in a bundled link should 158 have the same Link Type, the same Traffic Engineering metric, the 159 same set of resource classes at each end of the links, and must begin 160 and end on the same pair of LSRs. 162 There should be not any other restrictions on WSON bundling. For 163 each WDM node, not all the fibers can necessarily be connected to any 164 other fibers. So different ports connected to different separate 165 component links which will be bundled into one TE Link always have 166 different connectivity in the same node. For example, Fiber1 on the 167 west side can be connected to Fiber3 and Fiber4 on the east side, but 168 Fiber2 on the west side can not be connected to Fiber 3 and Fiber4 on 169 the east side. If Fiber1 and Fiber2 are necessary to be bundled into 170 one TE link, they could still be bundled though they have different 171 connectivity. The connectivity constraint and wavelength conversion 172 capability/availability information between the bundled links and 173 fibers on the east side should be a union (maximum) of connectivity 174 constraint and wavelength conversion capability/availability 175 information between the component links and fibers on the east side. 176 So the bundled link can be connected to Fiber3 and Fiber4 though 177 there is not any connectivity between the component link (Fiber2) and 178 other fibers on east side. 180 If one GMPLS control plane instance only controls the LSC network, 181 each wavelength should be considered as a label but not as a TE Link. 183 Link bundling should be done on the level of fiber. In MRN/MLN 184 (e.g., SDH/SONET over ODUk over LSC, ODUk over LSC and PSC over LSC), 185 service provider may deal with wavelengths as links or component link 186 from the perspective of a client layer. The case where link bundle 187 is applied in MRN/MLN is further for consideration. The scope of 188 this draft is cases where wavelengths are viewed as labels. 190 2.2. Connectivity Constraint Information and Wavelength Conversion 191 Capability/Availability of a WSON Node 193 Different ports connected to different component links which will be 194 bundled into one TE Link always have different connectivity in the 195 same node in WSON. Although these component links can be bundled 196 into a TE Link, connectivity constraint information and wavelength 197 conversion capability/availability information in one node have to be 198 affected. They should be summarized after using link bundle. 200 Link1 Wavelength Switch Optical Network Node 201 ________ +----------------------------------+ 202 / \ | | 203 / | | | 204 | '. Fiber1 | +---------------------+ |Fiber4 205 ___|______|________|______|_____________________|_____|______ 206 --+-------+--------+------+---------------------+-----+------ 207 | | | | | | 208 | | | | Wavelength Switch | | 209 | |Fiber2 | |Demultiplex/Multiplex| |Fiber5 210 __|________|_______|______| |_____|______ 211 --+--------+-------+------+`-._ _.-'-----+------ 212 | | | | `-._ ,,-' | | 213 | | | | `=,='' | | 214 | |Fiber3 | | _.-' `-._ | |Fiber6 215 __|_______|________|______| ,.-' `-._ |_____|______ 216 ---+------+--------+------+' '+-----+------ 217 \ / | | | | 218 \ / | +---+ +--+ | 219 `. / | | +---------------------+ | | 220 -------- | | +---------------------+ | | 221 Link Bundle | | | Wavelength | | | 222 + +---+ Converter +--+ + 223 | +---------------------+ | 224 | | 225 | | 226 +----------------------------------+ 228 Figure 1: Link Bundle of WSON 230 Figure 1 shows a typical WDM node, which consists of a Wavelength 231 Switch module, a Multiplexer/DeMultiplexer module, and a Wavelength 232 Converter module. In this example, there are six directions on the 233 line side. For example, in an 80-wavelength system, each fiber of 234 the line side contains 80 wavelengths, and traffic can be carried by 235 each wavelength. The wavelength can be switched to a different 236 direction (or a different fiber) at the WDM node. But there may be a 237 limitation for wavelength conversion, so that not every wavelength 238 can be switched to any other wavelength on any other fiber. 240 Some scenarios are assumed as followings: 242 There is connectivity between (Fiber1, Fiber4), (Fiber2, Fiber6) and 243 (Fiber3, Fiber5). 245 Lambda 1 on an incoming fiber 1 might only be converted to lambda 2, 246 lambda 3 and lambda 4 on outgoing fiber4. Lambda 2 on an incoming 247 fiber 1 might only be converted to lambda 7 and lambda 8 on outgoing 248 fiber4. Other wavelengths on Fiber1 can only be connected to the 249 same wavelengths on Fiber4. 251 Lambda 1 on an incoming fiber 2 might only be converted to lambda 4 252 and lambda 5 on outgoing fiber6. Other wavelengths on Fiber2 can 253 only be connected to the same wavelengths on Fiber6. 255 Lambda 3 on an incoming fiber 3 might only be converted to lambda 7 256 and lambda 8 on outgoing fiber5. Lambda 1 on an incoming fiber 3 257 might only be converted to lambda 5 and lambda 6 on outgoing fiber5. 258 Other wavelengths on Fiber3 can only be connected to the same 259 wavelengths on Fiber5. 261 So node information used by path computation entity is as followings: 263 Connectivity Constraint: 265 [Fiber1--->Fiber4] 267 [Fiber2--->Fiber6] 269 [Fiber3--->Fiber5] 271 Wavelength Conversion Capability: 273 [Fiber1:lambda1----> Fiber4:lambda2, lambda3, lambda4] 275 [Fiber1:lambda2----> Fiber4:lambda7, lambda8] 277 [Fiber2:lambda1----> Fiber6:lambda4, lambda5] 279 [Fiber3:lambda1----> Fiber5:lambda5, lambda6] 281 [Fiber3:lambda3----> Fiber5:lambda7, lambda8] 283 Wavelength Conversion Availability (same as wavelength conversion 284 capability): 286 [Fiber1:lambda1----> Fiber4:lambda2, lambda3, lambda4] 288 [Fiber1:lambda2----> Fiber4:lambda7, lambda8] 290 [Fiber2:lambda1----> Fiber6:lambda4, lambda5] 292 [Fiber3:lambda1----> Fiber5:lambda5, lambda6] 294 [Fiber3:lambda3----> Fiber5:lambda7, lambda8] 296 When Fiber1, Fiber2 and Fiber3 are bundled into one TE Link (Link1), 297 there should be a maximum connectivity between (Link1, Fiber4), 298 (Link1, Fiber5) and (Link1, Fiber6) which must be known to path 299 computation entity. If path computation entity keep having the 300 connectivity information between (Fiber1, Fiber4), (Fiber2, Fiber6) 301 and (Fiber3, Fiber5), it would be better for centralized RWA. The 302 connectivity constraint and wavelength conversion capability/ 303 availability information among bundled/unbundled links is the union 304 of connectivity constraint and wavelength conversion capability/ 305 availability information among component links. Any connectivity 306 constraint information and wavelength conversion capability/ 307 availability information among component links and other TE Links 308 (unbundled) should not be flooded any more. Node information used by 309 path computation entity after using Link Bundle is as followings: 311 Connectivity Constraint: 313 [Link1--->Fiber4] 315 [Link1--->Fiber5] 317 [Link1--->Fiber6] 319 Wavelength Conversion Capability: 321 [Link1:lambda1----> Fiber4:lambda2, lambda3, lambda4] 323 [Link1:lambda2----> Fiber4:lambda7, lambda8] 325 [Link1:lambda1----> Fiber6:lambda4, lambda5] 327 [Link1:lambda3----> Fiber5:lambda7, lambda8] 329 [Link1:lambda1----> Fiber5:lambda5, lambda6] 331 Wavelength Conversion Availability: 333 [Link1:lambda1----> Fiber4:lambda2, lambda3, lambda4] 335 [Link1:lambda2----> Fiber4:lambda7, lambda8] 337 [Link1:lambda1----> Fiber6:lambda4, lambda5] 339 [Link1:lambda3----> Fiber5:lambda7, lambda8] 341 [Link1:lambda1----> Fiber5:lambda5, lambda6] 343 If Fiber5 and Fiber6 are also bundled into one TE Link (Link2), node 344 information used by path computation entity after using Link Bundle 345 again is as followings: 347 Connectivity Constraint: 349 [Link1--->Fiber4] 351 [Link1--->Link2] 353 Wavelength Conversion Capability: 355 [Link1:lambda1----> Fiber4:lambda2, lambda3, lambda4] 357 [Link1:lambda2----> Fiber4:lambda7, lambda8] 359 [Link1:lambda1----> Link2:lambda4, lambda5, lambda6] 361 [Link1:lambda3----> Link2:lambda7, lambda8] 363 Wavelength Conversion Availability: 365 [Link1:lambda1----> Fiber4:lambda2, lambda3, lambda4] 367 [Link1:lambda2----> Fiber4:lambda7, lambda8] 369 [Link1:lambda1----> Link2:lambda4, lambda6] 371 [Link1:lambda1----> Link2:lambda5, lambda5] (Two available wavelength 372 conversions) 374 [Link1:lambda3----> Link2:lambda7, lambda8] 375 It is assumed that a wavelength switch path is along the fiber3 of 376 Link1 and fiber5 of Link2 using the wavelength conversion between 377 lambda1 and lambda5. So wavelength conversion availability used by 378 path computation entity again is as followings: 380 [Link1:lambda1----> Fiber4:lambda2, lambda3, lambda4] 382 [Link1:lambda2----> Fiber4:lambda7, lambda8] 384 [Link1:lambda1----> Link2:lambda4, lambda6] 386 [Link1:lambda1----> Link2:lambda5] (Remain an available wavelength 387 conversion) 389 [Link1:lambda3----> Link2:lambda7, lambda8] 391 Upon the above scenario, if one of the available wavelength 392 conversions among component links is occupied, the available 393 wavelength conversions among the associated bundled links must be 394 summarized and advertised again. 396 Another WSON node which connected to the same bundled link must 397 summary its connectivity constraint information and wavelength 398 conversion capability/availability information by the same means and 399 principle as the peer node. 401 If path computation entity (e.g., PCE) get the connectivity 402 constraint and wavelength conversion capability/availability 403 information via IGP, the summarized information should be flooded in 404 terms of [WSON-ENCODE] and [WSON-INFO] (i.e., Connectivity Matrix and 405 OEOWavelength ConverterInfo/AvailableWavelengthConverters). 407 2.3. Available Wavelength and Wavelength Constraint Information of a 408 Link 410 Link Bundle is accomplished by performing information aggregation/ 411 abstraction. So the available wavelength information and the 412 wavelength constraint information will be lost after component links 413 are bundled into a TE Link. If the computational entity performing 414 routing computation and wavelength assignment without the available 415 wavelength information on component links, they could not perform 416 efficient and accurate path computation. There are several RWA 417 computation architectures: 419 o Fully Centralized: In the case where a centralized PCE is 420 responsible for both routing and wavelength assignment or separate 421 centralized PCEs perform routing and wavelength assignment, they 422 all require PCEs to have detailed link wavelength utilization 423 information. They also require PCEs to have detailed node 424 connectivity constraint information and wavelength conversion 425 capability/availability information. [WSON-INFO] provides 426 efficient encodings of information needed by RWA and extends GMPLS 427 IGP to collect this information. Obviously, PCEs only has 428 aggregate wavelength usage (bandwidth) information in term of 429 [RFC4201] after component links bundled into TE links without any 430 IGP extension or any configuration of TED. In this architecture, 431 there are two kinds of component link selection: 433 1. Distributed Component Link Selection: If component links are 434 selected hop-by-hop by each node along the path, wavelength 435 assignment has to be performed at the level of bundled link. 436 An LSP originator can control and record the resource by an 437 explicit route, i.e., ERO and RRO. Bundled link and the 438 wavelength have to be specified in the ERO objects. The 439 selection of the component link within the bundle link is a 440 local decision, but the nodes must select an appropriate 441 component link where there are acceptable wavelengths 442 specified in ERO. If PCEs have no any wavelength availability 443 information on any component links, it can easily lead to 444 blocking problems during the process of component links 445 selection. 447 2. Centralized Component Link Selection: If component link 448 selection and wavelength assignment are performed within one 449 centralized PCE, the LSP originator must explicitly specify 450 resource at the level of (Bundled Link, Component Link, and 451 Wavelength/Label). [EXPLICIT-CONTROL-BUNDLE] defines 452 extensions to perform explicit label/resource control over 453 bundled TE link by ERO and RRO subobject. So the LSP 454 originator should use the ERO and RRO subobject to specify the 455 component link identifier for resource control and recording 456 over TE link bundles. If PCEs have to know information of 457 component links via IGP, it is not significant to apply Link 458 Bundle in this case. How PCEs get the information of 459 component links and nodes without IGP is further for study. 460 There are some approaches which have been described in [PCE- 461 TED-ALTERNATIVE]. 463 In all above cases it requires PCEs to have the wavelength 464 availability information and wavelength constraint information 465 on component links and connectivity constraint information and 466 wavelength conversion capability/availability information in 467 nodes. But this information of component links will be hided 468 after component links are bundled into one TE link. It can be 469 resolved by the IGP extension to get this information defined 470 in this draft. PCE can create the TED via IGP. It also can be 471 created by the alternative approaches which have been described 472 in [PCE-TED-ALTERNATIVE]. 474 o Centralized Routing + Distributed Wavelength Assignment: In the 475 case where a centralized PCE was assumed to compute paths with 476 distributed wavelength assignment, it is not necessary for the PCE 477 to have the wavelength availability information and wavelength 478 constraint information on component links and connectivity 479 constraint information and wavelength conversion capability/ 480 availability information in nodes, but this information of 481 component links is still hided in bundled links. In this case 482 component link selection and wavelength assignment should be 483 simultaneously done hop-by-hop to reduce higher blocking 484 probability. But in some case service provider have to explicitly 485 specify which component link within a bundled TE link should be 486 used for a given LSP for administrative purpose. For example, 487 [PC-SPC-EXT] defines a conversion between PC (Permanent 488 Connections) and SPC (Soft Permanent Connections) in a GMPLS 489 enabled transport network. When PC whose path is passing some 490 bundled links is converted to SPC, we should explicitly specify 491 which component links should be used on bundled links via ERO 492 subobjects defined in [EXPLICIT-CONTROL-BUNDLE]. Otherwise the 493 component links which are selected by nodes along the path may be 494 inconsistent with the ones which actually be used by PC. In order 495 to reduce higher blocking probability, wavelengths (labels) and 496 component links should be simultaneously specified. If component 497 links and wavelengths have to be explicitly specified via ERO 498 subobjects define in [EXPLICIT-CONTROL-BUNDLE], PCE should have 499 the wavelength utilization information and wavelength conversion 500 capability/availability information. PCEs can get this 501 information of component links and nodes via IGP or without IGP. 503 o Fully Distributed: In the case fully distributed routing 504 computation and wavelength assignment, it has the highest blocking 505 probability among all the RWA computation architectures with 506 limited or no wavelength conversions. Crankback defined in 507 RFC4920 is a scheme where the node unable to progress the 508 connection setup due to blocked resource returns information to 509 source node to allow new connection setup attempts to be made 510 avoiding the blocked resources. But it will still lead to 511 crankback frequently and be inefficient in the signaling protocol. 512 In this case, it is not necessary for PCEs to have the wavelength 513 utilization information. As the previous case, component link 514 selections and wavelength assignment should be simultaneously done 515 hop-by-hop to reduce higher blocking probability. 517 In all above RWA computation architectures, if the computational 518 entities have the wavelength utilization information, it can 519 calculate accurate paths and reduce blocking probability. 521 2.3.1. Routing Consideration 523 In the general case of limited or no wavelength conversion, 524 wavelength availability information is essential to perform efficient 525 and accurate path computation. PCE can get this information via IGP. 526 [WSON-INFO] provides efficient encodings of information needed by RWA 527 process in WSON and extends GMPLS IGP. [PCE-TED-ALTERNATIVE] also 528 give other alternative methods where nodes can send this information 529 to PCEs without IGP. There should be a fact in both means of TED 530 creation and maintenance that wavelengths utilization information 531 will be lost after component links are bundled into a TE link in 532 terms of [RFC4201]. Hence, this document defines the IGP extensions 533 to Link Bundle [RFC4201] to summarize the available wavelengths 534 information and wavelengths constraint information of component 535 links. This summarized information is one of the traffic parameters 536 to be advertised for a bundled link. The most important thing in 537 this IGP extension to [RFC4201] is that any other information about 538 component links must not flooded except the summarized wavelengths 539 availability information and wavelength constraint information. 540 Following IGP extension defined in this document is limited to WSON. 542 2.3.1.1. Wavelengths Constraint Information of Bundled Link 544 [WSON-INFO] extends GMPLS IGP to provide efficient encodings of 545 information (e.g., wavelength conversion constraints and wavelength 546 connectivity information of node, wavelength availability information 547 and wavelength constraint information of Link) needed by RWA process 548 in WSON. [WSON-ENCODE] defines a Port Wavelength Restriction sub-TLV 549 for encoding of wavelength constraint information and a Wavelength 550 Set sub-TLV for encoding of available wavelengths information. 552 This document extends Link Bundle [RFC4201] to make wavelength 553 constraint information be a traffic parameter of bundled link. A new 554 traffic parameter which is encoded with Port Wavelength Restriction 555 sub-TLV defined in [WSON-ENCODE] can be introduced to extend 556 [RFC4201] to carry wavelength constraint information of a bundled 557 link. This information must be summarized from all component links 558 on a bundled link and should be a union of all wavelengths constraint 559 information on all component links. The wavelengths constraint 560 information of a bundled link is the union of the wavelengths 561 constraint information of all the component links. How to calculate 562 this summarization is left as a local decision and out of this 563 document. 565 The wavelength that an optical fiber can support is pre-configured, 566 static information. This information needs to be advertised only 567 once in the general case, because it is not expected to change 568 frequently when the network is running. But any change in 569 wavelengths constraint information of a component link results in a 570 change in the wavelengths constraint information of the bundled link. 571 The summarization must be recomputed and flooded again. 573 2.3.1.2. Wavelengths Availability Information of Bundled Link 575 This document extends Link Bundle [RFC4201] to make wavelength 576 availability information a traffic parameter of bundled link. A new 577 traffic parameter which is encoded with Wavelength Set Sub-TLV 578 defined in [WSON-ENCODE] can be introduced to extend [RFC4201] to 579 carry wavelength availability information of a bundled link. This 580 information must be summarized from all component links on a bundled 581 link and should be a union of all wavelengths availability 582 information on all component links. For example, one fiber (Fiber1) 583 can support lambda 1 to lambda 5 and lambda 8 to lambda 11, another 584 fiber (Fiber2) can support lambda4 to lambda 6 and lambda 9 to lambda 585 12. 587 The wavelength constraint information should be as followings: 589 Fiber 1: [lambda1-lambda5], [lambda8-lambda11] 591 Fiber 2: [lambda4-lambda6], [lambda9-lambda12] 593 The wavelength availability information should be as followings (same 594 as wavelength constraint): 596 Fiber 1: [lambda1-lambda5], [lambda8-lambda11] 598 Fiber 2: [lambda4-lambda6], [lambda9-lambda12] 600 After Fiber 1 and Fiber2 are bundled into one TE Link (Link1), the 601 wavelength constraint information of bundled link should be as 602 followings: 604 Link1: [lambda1-lambda6], [lambda8-lambda12] 606 The wavelength availability information should be as followings: 608 Link1: [lambda1-lambda3] 610 Link1: (lambda4, lambda4) (two lambda4 wavelengths are available) 612 Link1: (lambda5, lambda5) (two lambda5 wavelengths are available) 614 Link1: [lambda6-lambda8] 615 Link1: (lambda9, lambda9) (two lambda9 wavelengths are available) 617 Link1: [lambda10-lambda12] 619 If one wavelength is available in more than one component link, 620 available numbers of this wavelength are the summation from all 621 component links. This wavelength will be unavailable on a bundled 622 link after this wavelength is unavailable on all component links. 623 How to calculate this summarization is left as a local decision and 624 out of this document. 626 In WSON, the status information of a certain wavelength in a fiber 627 should be refreshed following any change. When a wavelength is 628 assigned to set up a wavelength LSP or released when a wavelength LSP 629 is torn down, the status information of this wavelength on each link 630 along the path should be updated. This information is dynamic 631 information and needs to be distributed to all computation points. 632 So any change in wavelengths availability information of a component 633 link results in a change in the wavelengths availability information 634 of the bundled link. The summarization must be recomputed and 635 flooded again. 637 If one of the component links goes down, the associated bundled link 638 remains up and continues to be advertised, provided that at least one 639 component link associated with the bundled link is up. The available 640 wavelength of the component link that is down is set to zero, and 641 wavelengths availability information of the bundle must be 642 recomputed. If all the component links associated with a given 643 bundled link are down, the bundled link MUST not be advertised into 644 OSPF/IS-IS in terms of [RFC4201]. 646 2.3.2. Other Consideration 648 Although link bundling is not used, several TE links also can be 649 advertised for one TE Link. Path computation entity should still 650 have the detailed wavelength availability information on this link to 651 perform RWA. This case is further for study. 653 2.4. Bidirectional Path Using Same Component Link and Wavelength on 654 Both Directions 656 Base on the requirement of carriers for simplified management to 657 reduce the OPEX, they would like to create an end-to-end path that 658 uses the same component links and the same wavelength on both 659 directions of each bundled link. For example, service provider may 660 require that original service should not be affected after unbundling 661 the bundled link into several component links (unbundled links). If 662 the LSP uses different component links on different directions of a 663 bundled link, it is very difficult in keeping the RSVP-TE signaling 664 state on different TE link of separate directions for this LSP after 665 the bundled link is unbundled. 667 Using the same component link on both directions of a bundled link is 668 sometimes required to control not only WSON but also other switching 669 capability network. Sometimes, with limited or no wavelength 670 conversion, the wavelength could not be available on the same 671 component link on both directions. So it may fail to select the same 672 component on both directions in a bundled link. If there are several 673 component links where there are some wavelengths available on both 674 directions, how to select a component link is a local decision. It 675 may looks at all available component links for the path then chooses 676 from those available at random. Also all available component links 677 are ordered (e.g., order by Traffic Engineering metric), it may chose 678 the first available on all component link. 680 There are two component link selection architectures. 682 2.4.1. Centralized Component Link Selection 684 In the case of a centralized PCE performs component link selection, 685 PCE should select the same component link on both directions of a 686 bundled link along the path. The component link selected by a 687 centralized PCE should be explicitly specified by the LSP originator 688 via ERO subobjects defined in [EXPLICIT-CONTROL-BUNDLE]. In order to 689 reduce blocking probability, wavelength assignment and component link 690 selection should be done simultaneously within one PCE. PCE is 691 responsible for using same component link and wavelength on both 692 directions of a bundle link. So in this case wavelengths and 693 component links have to be explicitly specified via ERO object and 694 ERO subobject. In the general case of limited or no wavelength 695 conversion, because it may actually be the case that the lambda is 696 only available in one direction on one component link, and the other 697 direction is only available on a different component link, PCE may 698 fail to calculate such path to meet the requirement of same component 699 link and wavelength on both direction of a bundle link. 701 2.4.2. Distributed Component Link Selection 703 In the case of distributed component link selection which is done 704 hop-by-hop by nodes along path, how to select the component link 705 could be the default policy of a node, but different nodes may apply 706 different policies in the interoperability environment. So each node 707 should be explicitly notified of bidirectional same component link 708 path request. 710 [WSON-SIGNALING] introduces a bit in Attributes Flags TLV of 711 LSP_ATTRIBUTES object defined in [RFC4420] to indicate that the 712 bidirectional same wavelength path should be created. To meet the 713 requirement of the bidirectional same component link path request, 714 this document add a similar bit in Attributes Flags TLV of 715 LSP_ATTRIBUTES object. 717 In this component link selection architecture, there are two 718 wavelength assignment approaches. 720 2.4.2.1. Centralized Wavelength Assignment 722 If a centralized PCE performs wavelength assignment, wavelength 723 assignment has to be performed at the level of bundled link. Bundled 724 link and the wavelength have to be specified in the ERO objects by 725 the LSP originator. The centralized PCE has to assign the same 726 wavelength on both directions of a bundled link or non-bundled link. 727 The LSP originator can only specify resource at the level of (Bundle 728 Link or Non-Bundled Link, Wavelength/Label). Ingress node adds the 729 bidirectional same component link path request in a LSP_ATTRIBUTES 730 object of Path message. 732 The path setup procedure is described below: 734 1. Ingress node adds the bidirectional same component link request 735 in a LSP_ATTRIBUTES object of Path message. If this Path message 736 is to be sent for a downstream bundled TE link, the node must 737 select the same component link where there are acceptable 738 wavelengths specified in ERO objects. If there are not 739 acceptable wavelengths on non-bundled links or component links of 740 a bundled link, Path message will be terminated and error 741 information is generated. 743 2. On reception of a Path message containing bidirectional same 744 component link indication in a LSP_ATTRIBUTES object, and next 745 hop Path message is to be sent for a downstream bundled TE link, 746 the node must select the same component link where there are 747 acceptable wavelengths specified in ERO objects. If there are 748 not acceptable wavelengths on non-bundled links or component 749 links of a bundled link, the Path message will be terminated, and 750 a PathErr message with a "Component Link Selection Error" 751 indication will be generated. 753 2.4.2.2. Distributed Wavelength Assignment 755 If wavelength assignment should be simultaneously done hop-by-hop, it 756 is necessary to notify each node the request of bidirectional same 757 component link on both directions of a bundle link and same 758 wavelength on such a component link. 760 The path setup procedure is described below: 762 1. Ingress node adds the request of the bidirectional same component 763 link on both direction of a bundled link and same wavelength on 764 such a component link in a LSP_ATTRIBUTES object of Path message. 765 If this Path message is to be sent for a downstream bundled TE 766 link, the node must select one component link where there are 767 acceptable same wavelengths available on both directions, then 768 copy them into Label Set object and forward the Path message to 769 downstream node. If there aren!_t acceptable wavelengths on non- 770 bundled links or component links of a bundled link, Path message 771 will be terminated and error information is generated. 773 2. On reception of a Path message containing the above indication in 774 a LSP_ATTRIBUTES object and Label Set object, there will be two 775 cases: 777 * If this Path message is to be sent for a downstream bundled TE 778 link, the node must select one component link where the Label 779 Set TLVs are acceptable and available on both directions in 780 it. If there are acceptable same wavelengths on both 781 directions on such a component link, then copy the values of 782 them into new Label Set TLVs, and forward the Path message to 783 the downstream node. Otherwise the Path message will be 784 terminated, and a PathErr message with a "Routing problem/ 785 Label Set" indication will be generated. 787 * If this Path message is to be sent for a downstream non- 788 bundled link, the receiver of message checks if the Label Set 789 TLVs are acceptable on both directions. If there are 790 acceptable same wavelengths on both directions, then copy the 791 values of them into new Label Set TLVs, and forward the Path 792 message to the downstream node. Otherwise the Path message 793 will be terminated, and a PathErr message with a "Routing 794 problem/Label Set" indication will be generated. 796 3. On reception of a Path message containing the above indication in 797 a LSP_ATTRIBUTES object and Label Set object, the egress node 798 verifies whether the Label Set TLVs are acceptable, if one or 799 more wavelengths are available on both directions in a component 800 link, then any one available wavelength could be selected. A 801 Resv message is generated and propagated to upstream node. 803 4. On reception of a Resv message containing the above indication in 804 a LSP_ATTRIBUTES object, the intermediate node allocates the 805 label to interfaces on both directions in the component link, and 806 then configures the local ROADM or OXC on both directions. 808 3. Link Bundling of Multi-Region Network 810 In MRN/MLN (e.g., SDH/SONET over ODUk over LSC, ODUk over LSC and PSC 811 over LSC), Adjustment Capacity refers to the property of a hybrid 812 node to interconnect different switching capabilities it provides 813 through its external interfaces [RFC5212]. This information allows 814 path computation to select an end-to-end multi-region path that 815 includes links of different switching capabilities that are joined by 816 LSRs that can adapt the signal between the links. If link bundling 817 is done, then the adjustment capacity information is also lost with 818 current GMPLS routing. GMPLS routing should be extended to meet this 819 requirement. This case is further for consideration. 821 4. Security Considerations 823 TBD. 825 5. IANA Considerations 827 TBD. 829 6. Acknowledgments 831 TBD. 833 7. Normative References 835 [EXPLICIT-CONTROL-BUNDLE] 836 Anca Zamfir, Zafar Ali, and Dimitri Papadimitriou, 837 "Component Link Recording and Resource Control for TE Link 838 Bundles", July 2008. 840 [PC-SPC-EXT] 841 D. Caviglia, D. Ceccarelli, D. Bramanti, and D. Li, 842 "RSVP-TE Signaling Extension For The Conversion Between 843 Permanent Connections And Soft Permanent Connections In A 844 GMPLS Enabled Transport", October 2008. 846 [PCE-TED-ALTERNATIVE] 847 Y. Lee, G. Bernstein, and D. Li, "Alternative Approaches 848 to Traffic Engineering Database Creation and Maintenance 849 for Path Computation Elements", September 2008. 851 [WSON-ENCODE] 852 G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "Routing and 853 Wavelength Assignment Information Encoding for Wavelength 854 Switched Optical Networks", December 2008. 856 [WSON-FRAME] 857 G. Bernstein, Y. Lee, and W. Imajuku, "Framework for GMPLS 858 and PCE Control of Wavelength Switched Optical Networks", 859 February 2009. 861 [WSON-INFO] 862 G. Bernstein, Y. Lee, D. Li, and W. Imajuku, "Routing and 863 Wavelength Assignment Information for Wavelength Switched 864 Optical Networks", November 2008. 866 Author's Address 868 Xihua Fu (editor) 869 ZTE Corporation 870 West District,ZTE Plaza,No.10,Tangyan South Road,Gaoxin District 871 Xi'an 710065 872 P.R.China 874 Phone: +8615802921223 875 Email: fu.xihua@zte.com.cn 876 URI: http://www.zte.com.cn