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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 CCAMP Working Group S. Belotti, Ed. 3 Internet-Draft P. Grandi 4 Intended status: Informational Alcatel-Lucent 5 Expires: March 24, 2012 D. Ceccarelli, Ed. 6 D. Caviglia 7 Ericsson 8 F. Zhang 9 D. Li 10 Huawei Technologies 11 September 21, 2011 13 Information model for G.709 Optical Transport Networks (OTN) 14 draft-ietf-ccamp-otn-g709-info-model-01 16 Abstract 18 The recent revision of ITU-T recommendation G.709 [G.709-v3] has 19 introduced new fixed and flexible ODU containers in Optical Transport 20 Networks (OTNs), enabling optimized support for an increasingly 21 abundant service mix. 23 This document provides a model of information needed by the routing 24 and signaling process in OTNs to support Generalized Multiprotocol 25 Label Switching (GMPLS) control of all currently defined ODU 26 containers. 28 Status of this Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on March 24, 2012. 45 Copyright Notice 47 Copyright (c) 2011 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 respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 64 2. OSPF-TE requirements overview . . . . . . . . . . . . . . . . 4 65 3. RSVP-TE requirements overview . . . . . . . . . . . . . . . . 5 66 4. G.709 Digital Layer Info Model for Routing and Signaling . . . 5 67 4.1. Tributary Slot Granularity . . . . . . . . . . . . . . . . 8 68 4.1.1. Fall-back procedure . . . . . . . . . . . . . . . . . 10 69 4.2. Tributary Port Number . . . . . . . . . . . . . . . . . . 11 70 4.3. Signal type . . . . . . . . . . . . . . . . . . . . . . . 11 71 4.4. Bit rate and tolerance . . . . . . . . . . . . . . . . . . 13 72 4.5. Unreserved Resources . . . . . . . . . . . . . . . . . . . 13 73 4.6. Maximum LSP Bandwidth . . . . . . . . . . . . . . . . . . 13 74 4.7. Distinction between terminating and switching 75 capability . . . . . . . . . . . . . . . . . . . . . . . . 14 76 4.8. Priority Support . . . . . . . . . . . . . . . . . . . . . 16 77 4.9. Multi-stage multiplexing . . . . . . . . . . . . . . . . . 16 78 4.10. Generalized Label . . . . . . . . . . . . . . . . . . . . 17 79 5. Security Considerations . . . . . . . . . . . . . . . . . . . 17 80 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 81 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 17 82 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 83 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 84 9.1. Normative References . . . . . . . . . . . . . . . . . . . 18 85 9.2. Informative References . . . . . . . . . . . . . . . . . . 19 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 88 1. Introduction 90 GMPLS[RFC3945] extends MPLS to include Layer-2 Switching (L2SC), 91 Time-Division Multiplexing (e.g., SONET/SDH, PDH, and OTN), 92 Wavelength (OCh, Lambdas) Switching and Spatial Switching (e.g., 93 incoming port or fiber to outgoing port or fiber). 95 The establishment of LSPs that span only interfaces recognizing 96 packet/cell boundaries is defined in [RFC3036, RFC3212, RFC3209]. 97 [RFC3471] presents a functional description of the extensions to 98 Multi-Protocol Label Switching (MPLS) signaling required to support 99 GMPLS. ReSource reserVation Protocol-Traffic Engineering (RSVP-TE) 100 -specific formats,mechanisms and technology specific details are 101 defined in [RFC3473]. 103 From a routing perspective, Open Shortest Path First-Traffic 104 Engineering (OSPF-TE) generates Link State Advertisements (LSAs) 105 carrying application-specific information and floods them to other 106 nodes as defined in [RFC5250]. Three types of opaque LSA are 107 defined, i.e. type 9 - link-local flooding scope, type 10 - area- 108 local flooding scope, type 11 - AS flooding scope. 110 Type 10 LSAs are composed of a standard LSA header and a payload 111 including one top-level TLV and possible several nested sub-TLVs. 112 [RFC3630] defines two top-level TLVs: Router Address TLV and Link 113 TLV; and nine possible sub-TLVs for the Link TLV, used to carry link 114 related TE information. The Link type sub-TLVs are enhanced by 115 [RFC4203] in order to support GMPLS networks and related specific 116 link information. In GMPLS networks each node generates TE LSAs to 117 advertise its TE information and capabilities (link-specific or node- 118 specific)through the network. The TE information carried in the LSAs 119 are collected by the other nodes of the network and stored into their 120 local Traffic Engineering Databases (TED). 122 In a GMPLS enabled G.709 Optical Transport Networks (OTN), routing 123 and signaling are fundamental in order to allow automatic calculation 124 and establishment of routes for ODUk LSPs. The recent revision of 125 ITU-T Recommendation G.709 [G709-V3] has introduced new fixed and 126 flexible ODU containers that augment those specified in foundation 127 OTN. As a result, it is necessary to provide OSPF-TE and RSVP-TE 128 extensions to allow GMPLS control of all currently defined ODU 129 containers. 131 This document provides the information model needed by the routing 132 and signaling processses in OTNs to allow GMPLS control of all 133 currently defined ODU containers. 135 OSPF-TE and RSVP-tE requirements are defined in [OTN-FWK], while 136 protocol extensions are defined in [OTN-OSPF] and [OTN-RSVP]. 138 1.1. Terminology 140 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 141 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 142 document are to be interpreted as described in [RFC2119]. 144 2. OSPF-TE requirements overview 146 [OTN-FWK] provides a set of functional routing requirements 147 summarized below : 149 - Support for link multiplexing capability advertisement: The 150 routing protocol has to be able to carry information regarding the 151 capability of an OTU link to support different type of ODUs 153 - Support of any ODUk and ODUflex: The routing protocol must be 154 capable of carrying the required link bandwidth information for 155 performing accurate route computation for any of the fixed rate 156 ODUs as well as ODUflex. 158 - Support for differentiation between switching and terminating 159 capacity 161 - Support for the client server mappings as required by 162 [G.7715.1]. The list of different mappings methods is reported in 163 [G.709-v3]. Since different methods exist for how the same client 164 layer is mapped into a server layer, this needs to be captured in 165 order to avoid the set-up of connections that fail due to 166 incompatible mappings. 168 - Support different priorities for resource reservation. How many 169 priorities levels should be supported depends on operator 170 policies. Therefore, the routing protocol should be capable of 171 supporting either no priorities or up to 8 priority levels as 172 defined in [RFC4202]. 174 - Support link bundling of component links at the same line rate 175 and with same muxing hierarchy. 177 - Support for Tributary Slot Granularity (TSG) advertisement. 179 3. RSVP-TE requirements overview 181 [OTN-FWK] also provides a set of functional signaling requirements 182 summarized below : 184 - Support for LSP setup of new ODUk/ODUflex containers with 185 related mapping and multiplexing capabilities 187 - Support for LSP setup using different Tributary Slot granularity 189 - Support for Tributary Port Number allocation and negoziation 191 - Support for constraint signaling 193 - Support for TSG signaling 195 4. G.709 Digital Layer Info Model for Routing and Signaling 197 The digital OTN layered structure is comprised of digital path layer 198 networks (ODU) and digital section layer networks (OTU). An OTU 199 section layer supports one ODU path layer as client and provides 200 monitoring capability for the OCh. An ODU path layer may transport a 201 heterogeneous assembly of ODU clients. Some types of ODUs (i.e., 202 ODU1, ODU2, ODU3, ODU4) may assume either a client or server role 203 within the context of a particular networking domain. ITU-T G.872 204 recommendation provides two tables defining mapping and multiplexing 205 capabilities of OTNs, which are reproduced below. 207 +--------------------+--------------------+ 208 | ODU client | OTU server | 209 +--------------------+--------------------+ 210 | ODU 0 | - | 211 +--------------------+--------------------+ 212 | ODU 1 | OTU 1 | 213 +--------------------+--------------------+ 214 | ODU 2 | OTU 2 | 215 +--------------------+--------------------+ 216 | ODU 2e | - | 217 +--------------------+--------------------+ 218 | ODU 3 | OTU 3 | 219 +--------------------+--------------------+ 220 | ODU 4 | OTU 4 | 221 +--------------------+--------------------+ 222 | ODU flex | - | 223 +--------------------+--------------------+ 225 Figure 1: OTN mapping capability 227 +=================================+=========================+ 228 | ODU client | ODU server | 229 +---------------------------------+-------------------------+ 230 | 1,25 Gbps client | | 231 +---------------------------------+ ODU 0 | 232 | - | | 233 +=================================+=========================+ 234 | 2,5 Gbps client | | 235 +---------------------------------+ ODU 1 | 236 | ODU 0 | | 237 +=================================+=========================+ 238 | 10 Gbps client | | 239 +---------------------------------+ ODU 2 | 240 | ODU0,ODU1,ODUflex | | 241 +=================================+=========================+ 242 | 10,3125 Gbps client | | 243 +---------------------------------+ ODU 2e | 244 | - | | 245 +=================================+=========================+ 246 | 40 Gbps client | | 247 +---------------------------------+ ODU 3 | 248 | ODU0,ODU1,ODU2,ODU2e,ODUflex | | 249 +=================================+=========================+ 250 | 100 Gbps client | | 251 +---------------------------------+ ODU 4 | 252 |ODU0,ODU1,ODU2,ODU2e,ODU3,ODUflex| | 253 +=================================+=========================+ 254 |CBR clients from greater than | | 255 |2.5 Gbit/s to 100 Gbit/s: or | | 256 |GFP-F mapped packet clients from | ODUflex | 257 |1.25 Gbit/s to 100 Gbit/s. | | 258 +---------------------------------+ | 259 | - | | 260 +=================================+=========================+ 262 Figure 2: OTN multiplexing capability 264 How an ODUk connection service is transported within an operator 265 network is governed by operator policy. For example, the ODUk 266 connection service might be transported over an ODUk path over an 267 OTUk section, with the path and section being at the same rate as 268 that of the connection service (see Table 1). In this case, an 269 entire lambda of capacity is consumed in transporting the ODUk 270 connection service. On the other hand, the operator might exploit 271 different multiplexing capabilities in the network to improve 272 infrastructure efficiencies within any given networking domain. In 273 this case, ODUk multiplexing may be performed prior to transport over 274 various rate ODU servers (as per Table 2) over associated OTU 275 sections. 277 From the perspective of multiplexing relationships, a given ODUk may 278 play different roles as it traverses various networking domains. 280 As detailed in [OTN-FWK], client ODUk connection services can be 281 transported over: 283 o Case A) one or more wavelength sub-networks connected by optical 284 links or 286 o Case B) one or more ODU links (having sub-lambda and/or lambda 287 bandwidth granularity) 289 o Case C) a mix of ODU links and wavelength sub-networks. 291 This document considers the TE information needed for ODU path 292 computation and parameters needed to be signaled for LSP setup. 294 The following sections list and analyze each type of data that needs 295 to be advertised and signaled in order to support path computation 296 and LSP setup. 298 4.1. Tributary Slot Granularity 300 ITU-T recommendations define two types of TS but each link can only 301 support a single type at a given time. The rules to be followed when 302 selecting the TS to be used are: 304 - If both ends of a link can support both 2.5Gbps TS and 1.25Gbps 305 TS, then the link will work with 1.25Gbps TS. 307 - If one end can support the 1.25Gbps TS, and another end the 308 2.5Gbps TS, the link will work with 2.5Gbps TS. 310 The tributary slot type information is one of the parameters needed 311 to correctly configure physical interfaces. When setting up and HO- 312 ODUk/OTUk LSP or an H-LSP/FA, the penultimate node of the path might 313 need to choose among interfaces supporting 1,25 Gbps or 2,5 Gbps. 314 The choice depends on the type of client signal (e.g. an ODU0 can 315 only be supported by 1.25Gbps TSG) and this information needs to be 316 carried in the signaling messages. 318 In order to carry the tributary slot granularity information, an 319 object that can be examinded by the penultimate hop and terminated 320 just by the end nodes of the path is needed. The utilization of the 321 label is not the correct choice as it can be changed hop by hop. One 322 possible solution is the G-PID field of the GENERALIZED LABEL REQUEST 323 Object. The following table shows the different mapping 324 possibilities depending on the TSG types. The client types are shown 325 in the left column, while the different OPUk server and related TSGs 326 are listed in the top row. 328 +------------------------------------------------+ 329 | 2.5G TS || 1.25G TS | 330 | OPU2 | OPU3 || OPU1 | OPU2 | OPU3 | OPU4 | 331 +-------+------------------------------------------------+ 332 | | - | - || AMP | GMP | GMP | GMP | 333 | ODU0 | | || PT=20 | PT=21 | PT=21 | PT=21 | 334 +-------+------------------------------------------------+ 335 | | AMP | AMP || - | AMP | AMP | GMP | 336 | ODU1 | PT=20 | PT=20 || | PT=21 | PT=21 | PT=21 | 337 +-------+------------------------------------------------+ 338 | | - | AMP || - | - | AMP | GMP | 339 | ODU2 | | PT=20 || | | PT=21 | PT=21 | 340 +-------+------------------------------------------------+ 341 | | - | - || - | - | GMP | GMP | 342 | ODU2e | | || | | PT=21 | PT=21 | 343 +-------+------------------------------------------------+ 344 | | - | - || - | - | - | GMP | 345 | ODU3 | | || | | | PT=21 | 346 +-------+------------------------------------------------+ 347 | | - | - || - | GMP | GMP | GMP | 348 | ODUfl | | || | PT=21 | PT=21 | PT=21 | 349 +-------+------------------------------------------------+ 351 Figure 3: ODUj into OPUk mapping types 353 The G-PID value defined in [RFC 4328] is associated to the mapping 354 with 2.5Gbps TSG type (G-PID = 47). A new G-PID value has to be 355 defined (TBA by IANA) in order to cover the mapping on 1.25Gbps TSG 356 type. 358 The G-PID information is not enough to have a complete choice since 359 the penultimate hop node has to distinguish between interfaces with 360 the same TSG (e.g. 1.25Gbps) whether the interface is able to support 361 the right hierarchy, i.e. it is possible to have two interfaces both 362 at 1.25 TSG but only one is supporting ODU0. 364 A dedicated optional object should to be defined in order to carry 365 the multiplexing hierarchy and have a more precise choice capability. 366 In this way, when the penultimate node receives the GENERALIZED LABEL 367 REQUEST Object, the G-PID value together with the ODU bandwdith 368 included into the Traffic Parameters Object allow desuming the 369 correct TSG value. 371 As an example it is possible to consider the setup of an ODU3 path 372 that is going to carry an ODU0. In this case it is needed the 373 support of 1,25 GBps TS. The information related to the TSG is 374 carried via the G-PID and node C, having two different interfaces 375 toward D with different TSG, can choose the right one as depicted in 376 the following figure. 378 ODU0 379 ________________________________________ 380 | | 381 +--------+ +--------+ +--------+ +--------+ 382 | | | | | | 1.25 | | 383 | Node | | Node | | Node +------+ Node | 384 | A +------+ B +------+ C | ODU3 | D | 385 | | ODU3 | | ODU3 | +------+ | 386 +--------+ 1.25 +--------+ 1.25 +--------+ 2.5 +--------+ 388 Figure 4: TSG in signaling 390 The TSG information is needed also in the routing protocol as the 391 ingress node (A in the previous example) needs to know if the 392 interfaces between C and D can support the required TSG. In case 393 they cannot, A will compute an alternate path from itself to D. 395 In a multi-stage multiplexing environment any layer can have a 396 different TSG structure, e.g. in a multiplexing hierarchy like 397 ODU0->ODU2->ODU3, the ODU3 can be structured at TSG=2.5 in order to 398 support an ODU2 connection, but this ODU2 connection can be a tunnel 399 for ODU0, and hence structured with 1.25 TSG. Therefore any 400 multiplexing level has to advertise his TSG capabilities in order to 401 allow a correct path computation by the end nodes (both of the ODUk 402 trail and of the H-LSP/FA). 404 4.1.1. Fall-back procedure 406 SG15 ITU-T G.798 recommendation describes the so called PT=21-to- 407 PT=20 interworking process that explains how two equipments with 408 interfaces with different PayloadType, and hence different TS 409 granularity (1.25Gbps vs. 2.5Gbps), can be coordinated so to permit 410 the equipment with 1.25 TS granularity to adapt his TS allocation 411 accordingly to the different TS granularity (2.5Gbps) of a neighbour. 413 Therefore, in order to let the NE change TS granularity accordingly 414 to the nieghbour requirements, the AUTOpayloadtype needs to be set. 415 When both the neighbors (link or trail) have been configured as 416 structured, the payload type received in the overhead is compared to 417 the transmitted PT. If they are different and the transmitted PT=21, 418 the node must fallback to PT=20. In this case the fall-back process 419 makes the system self consistent and the only reason for signaling 420 the TS granularity is to provide the correct label (i.e. label for 421 PT=21 has twice the TS number of PT=20). On the other side, if the 422 AUTOpayloadtype is not configured, the RSVP-TE consequent actions in 423 case of TS mismatch need to be defined. 425 4.2. Tributary Port Number 427 [RFC4328] supports only the deprecated auto-MSI mode which assumes 428 that the Tributary Port Number is automatically assigned in the 429 transmit direction and not checked in the receive direction. 431 As described in [G709-V3] and [G798-V3], the OPUk overhead in an OTUk 432 frame contains n (n = the total number of TSs of the ODUk) MSI 433 (Multiplex Structure Identifier) bytes (in the form of multi-frame), 434 each of which is used to indicate the association between tributary 435 port number and tributary slot of the ODUk. 437 The association between TPN and TS has to be configured by the 438 control plane and checked by the data plane on each side of the link. 439 (Please refer to [OTN-FWK] for further details). As a consequence, 440 the RSVP-TE signaling needs to be extended to support the TPN 441 assignment function. 443 4.3. Signal type 445 From a routing perspetive, [RFC 4203] allows advertising foundation 446 G.709 (single TS type) without the capability of providing precise 447 information about bandwidth specific allocation. For example, in 448 case of link bundling, dividing the unreserved bandwidth by the MAX 449 LSP bandwidth it is not possible to know the exact number of LSPs at 450 MAX LSP bandwidth size that can be set up. (see example fig. 3) 452 The lack of spatial allocation heavily impacts the restoration 453 process, because the lack of information of free resources highly 454 increases the number of crank-backs affecting network convergence 455 time. 457 Moreover actual tools provided by OSPF-TE only allow advertising 458 signal types with fixed bandwidth and implicit hierarchy (e.g. SDH/ 459 SONET networks) or variable bandwidth with no hierarchy (e.g. packet 460 switching networks) but do not provide the means for advertising 461 networks with mixed approach (e.g. ODUflex CBR and ODUflex packet). 463 For example, advertising ODU0 as MIN LSP bandwidth and ODU4 as MAX 464 LSP bandwidth it is not possible to state whether the advertised link 465 supports ODU4 and ODUflex or ODU4, ODU3, ODU2, ODU1, ODU0 and 466 ODUflex. Such ambiguity is not present in SDH networks where the 467 hierarchy is implicit and flexible containers like ODUFlex do not 468 exist. The issue could be resolved by declaring 1 ISCD for each 469 signal type actually supported by the link. 471 Supposing for example to have an equivalent ODU2 unreserved bandwidth 472 in a TE-link (with bundling capability) distributed on 4 ODU1, it 473 would be advertised via the ISCD in this way: 475 MAX LSP Bw: ODU1 477 MIN LSP Bw: ODU1 479 - Maximum Reservable Bandwidth (of the bundle) set to ODU2 481 - Unreserved Bandwidth (of the bundle) set to ODU2 483 Moreover with the current IETF solutions, ([RFC4202], [RFC4203]) as 484 soon as no bandwidth is available for a certain signal type it is not 485 advertised into the related ISCD, losing also the related capability 486 until bandwidth is freed. 488 In conclusion, the OSPF-TE extensions defined in [RFC4203] require a 489 different ISCD per signal type in order to advertise each supported 490 container. This motivates attempting to look for a more optimized 491 solution, without proliferations of the number of ISCD advertised. 492 The OSPF LSA is required to stay within a single IP PDU; 493 fragmentation is not allowed. In a conforming Ethernet environment, 494 this limits the LSA to 1432 bytes (Packet_MTU (1500 Bytes) - 495 IP_Header (20 bytes) - OSPF_Header (28 bytes) - LSA_Header (20 496 bytes)). 498 With respect to link bundling, the utilization of the ISCD as it is, 499 would not allow precise advertising of spatial bandwidth allocation 500 information unless using only one component link per TE link. 502 On the other hand, from a singaling point of view, [RFC4328] 503 describes GMPLS signaling extensions to support the control for G.709 504 OTNs [G709-V1]. However,[RFC4328] needs to be updated because it 505 does not provide the means to signal all the new signal types and 506 related mapping and multiplexing functionalities. 508 4.4. Bit rate and tolerance 510 In the current traffic parameters signaling, bit rate and tolerance 511 are implicitly defined by the signal type. ODUflex CBR and Packet 512 can have variable bit rates and tolerances (please refer to [OTN-FWK] 513 table 2); it is thus needed to upgrade the signaling traffic 514 patameters so to specify requested bit rates and tolerance values 515 during LSP setup. 517 4.5. Unreserved Resources 519 Unreserved resources need to be advertised per priority and per 520 signal type in order to allow the correct functioning of the 521 restoration process. [RFC4203] only allows advertising unreserved 522 resources per priority, this leads not to know how many LSPs of a 523 specific signal type can be restored. As example it is possible to 524 consider the scenario depicted in the following figure. 526 +------+ component link 1 +------+ 527 | +------------------+ | 528 | | component link 2 | | 529 | N1 +------------------+ N2 | 530 | | component link 3 | | 531 | +------------------+ | 532 +------+ +---+--+ 534 Figure 5: Concurrent path computation 536 Suppose to have a TE link comprising 3 ODU3 component links with 537 32TSs available on the first one, 24TSs on the second, 24TSs on the 538 third and supporting ODU2 and ODU3 signal types. The node would 539 advertise a TE link unreserved bandwidth equal to 80 TSs and a MAX 540 LSP bandwidth equal to 32 TSs. In case of restoration the network 541 could try to restore 2 ODU3 (64TSs) in such TE-link while only a 542 single ODU3 can be set up and a crank-back would be originated. In 543 more complex network scenarios the number of crank-backs can be much 544 higher. 546 4.6. Maximum LSP Bandwidth 548 Maximum LSP bandwidth is currently advertised in the common part of 549 the ISCD and advertised per priority, while in OTN networks it is 550 only required for ODUflex advertising. This leads to a significant 551 waste of bits inside each LSA. 553 4.7. Distinction between terminating and switching capability 555 The capability advertised by an interface needs further distinction 556 in order to separate termination and switching capabilities. Due to 557 internal constraints and/or limitations, the type of signal being 558 advertised by an interface could be just switched (i.e. forwarded to 559 switching matrix without multiplexing/demultiplexing actions), just 560 terminated (demuxed) or both of them. The following figures help 561 explainig the switching and terminating capabilities. 563 MATRIX LINE INTERFACE 564 +-----------------+ +-----------------+ 565 | +-------+ | ODU2 | | 566 ----->| ODU-2 |----|----------|--------\ | 567 | +-------+ | | +----+ | 568 | | | \__/ | 569 | | | \/ | 570 | +-------+ | ODU3 | | ODU3 | 571 ----->| ODU-3 |----|----------|------\ | | 572 | +-------+ | | \ | | 573 | | | \| | 574 | | | +----+ | 575 | | | \__/ | 576 | | | \/ | 577 | | | ---------> OTU-3 578 +-----------------+ +-----------------+ 580 Figure 6: Switching and Terminating capabilities 582 The figure in the example shows a line interface able to: 584 - Multiplex an ODU2 coming from the switching matrix into and ODU3 585 and map it into an OTU3 587 - Map an ODU3 coming from the switching matrix into an OTU3 589 In this case the interface bandwidth advertised is ODU2 with 590 switching capability and ODU3 with both switching and terminating 591 capabilities. 593 This piece of information needs to be advertised together with the 594 related unreserved bandwidth and signal type. As a consequence 595 signaling must have the possibility to setup an LSP allowing the 596 local selection of resources consistent with the limitations 597 considered during the path computation. 599 In figures 6 and 7 there are two examples of the need of termination/ 600 switching capability differentiation. In both examples all nodes are 601 supposed to support single-stage capability. The figure 6 addresses 602 a scenario in which a failure on link B-C forces node A to calculate 603 another ODU2 LSP path carrying ODU0 service along the nodes B-E-D. 604 Being D a single stage capable node, it is able to extract ODU0 605 service only from ODU2 interface. Node A has to know that from E to 606 D exists an available OTU2 link from which node D can extract the 607 ODU0 service. This information is required in order to avoid that 608 the OTU3 link is considered in the path computation. 610 ODU0 transparently transported 611 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 612 | ODU2 LSP Carrying ODU0 service | 613 | |'''''''''''''''''''''''''''''''''''''''''''| | 614 | | | | 615 | +----++ OTU2 +-----+ OTU2 +-----+ OTU2 ++----+ | 616 ODU0 | | Link | | Link | | Link | | ODU0 617 ---->| A |_________| B |_________| C |_________| D |----> 618 | | | | | | | | 619 +-----+ +--+--+ +-----+ ++--+-+ 620 | | | 621 OTU3| | | 622 Link| +-----+__________________| | 623 | | | OTU3 Link | 624 |____| E | | 625 | |_____________________| 626 +-----+ OTU2 Link 628 Figure 7: Switching and Terminating capabilities - Example 1 630 Figure 7 addresses the scenario in which the restoration of the ODU2 631 LSP (ABCD) is required. The two bundled component links between B 632 and E could be used, but the ODU2 over the OTU2 component link can 633 only be terminated and not switched. This implies that it cannot be 634 used to restore the ODU2 LSP (ABCD). However such ODU2 unreserved 635 bandwidth must be advertised since it can be used for a different 636 ODU2 LSP terminating on E, e.g. (FBE). Node A has to know that the 637 ODU2 capability on the OTU2 link can only be terminated and that the 638 restoration of (ABCD) can only be performed using the ODU2 bandwidth 639 available on the OTU3 link. 641 ODU0 transparently transported 642 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 643 | ODU2 LSP Carrying ODU0 service | 644 | |'''''''''''''''''''''''''''''''''''''''''''| | 645 | | | | 646 | +----++ OTU2 +-----+ OTU2 +-----+ OTU2 ++----+ | 647 ODU0 | | Link | | Link | | Link | | ODU0 648 ---->| A |_________| B |_________| C |_________| D |----> 649 | | | | | | | | 650 +-----+ ++-+-++ +-----+ +--+--+ 651 | | | | 652 OTU2| | | | 653 +-----+ Link| | | OTU3 +-----+ | 654 | | | | | Link | | | 655 | F |_______| | |___________| E |___________| 656 | | |_____________| | OTU2 Link 657 +-----+ OTU2 Link +-----+ 659 Figure 8: Switching and Terminating capabilities - Example 2 661 4.8. Priority Support 663 The IETF foresees that up to eight priorities must be supported and 664 that all of them have to be advertised independently on the number of 665 priorities supported by the implementation. Considering that the 666 advertisement of all the different supported signal types will 667 originate large LSAs, it is advised to advertise only the information 668 related to the really supported priorities. 670 4.9. Multi-stage multiplexing 672 With reference to the [OTN-FWK], introduction of multi-stage 673 multiplexing implies the advertisement of cascaded adaptation 674 capabilities together with the matrix access constraints. The 675 structure defined by IETF for the advertisement of adaptation 676 capabilities is ISCD/IACD as in [RFC4202] and [RFC5339]. 677 Modifications to ISCD/IACD, if needed, have to be addressed in the 678 releted encoding documents. 680 With respect to the routing, please note that in case of multi stage 681 muxing hierarchy (e.g. ODU1->ODU2->ODU3), not only the ODUk/OTUk 682 bandwidth (ODU3) and service layer bandwidth (ODU1) are needed, but 683 also the intermediate one (ODU2). This is a typical case of spatial 684 allocation problem. 686 Suppose in this scenario to have the following advertisement: 688 Hierarchy: ODU1->ODU2->ODU3 690 Number of ODU1==5 692 The number of ODU1 suggests that it is possible to have an ODU2 FA, 693 but it depends on the spatial allocation of such ODU1s. 695 It is possible that 2 links are bundled together and 3 696 ODU1->ODU2->ODU3 are available on a component link and 2 on the other 697 one, in such a case no ODU2 FA could be set up. The advertisement of 698 the ODU2 is needed because in case of ODU1 spatial allocation (3+2), 699 the ODU2 available bandwidth would be 0 (no ODU2 FA can be created), 700 while in case of ODU1 spatial allocation (4+1) the ODU2 available 701 bandwidth would be 1 (1 ODU2 FA can be created). 703 4.10. Generalized Label 705 The ODUk label format defined in [RFC4328] could be updated to 706 support new signal types defined in [G709-V3] but would hardly be 707 further enhanced to support possible new signal types. 709 Furthermore such label format may have scalability issues due to the 710 high number of labels needed when signaling large LSPs. For example, 711 when an ODU3 is mapped into an ODU4 with 1.25G tributary slots, it 712 would require the utilization of thirty-one labels (31*4*8=992 bits) 713 to be allocated while an ODUflex into an ODU4 may need up to eighty 714 labels (80*4*8=2560 bits). 716 A new flexible and scalable ODUk label format needs to be defined. 718 5. Security Considerations 720 TBD 722 6. IANA Considerations 724 TBD 726 7. Contributors 728 Jonathan Sadler, Tellabs 730 EMail: jonathan.sadler@tellabs.com 731 John Drake, Juniper 733 EMail: jdrake@juniper.net 735 8. Acknowledgements 737 The authors would like to thank Eve Varma and Sergio Lanzone for 738 their precious collaboration and review. 740 9. References 742 9.1. Normative References 744 [HIER-BIS] 745 K.Shiomoto, A.Farrel, "Procedure for Dynamically Signaled 746 Hierarchical Label Switched Paths", work in 747 progress draft-ietf-lsp-hierarchy-bis-08, February 2010. 749 [OTN-OSPF] 750 D.Ceccarelli,D.Caviglia,F.Zhang,D.Li,Y.Xu,P.Grandi,S.Belot 751 ti, "Traffic Engineering Extensions to OSPF for 752 Generalized MPLS (GMPLS) Control of Evolutive G.709 OTN 753 Networks", work in 754 progress draft-ceccarelli-ccamp-gmpls-ospf-g709-03, August 755 2010. 757 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 758 Requirement Levels", BCP 14, RFC 2119, March 1997. 760 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 761 (TE) Extensions to OSPF Version 2", RFC 3630, 762 September 2003. 764 [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in 765 Support of Generalized Multi-Protocol Label Switching 766 (GMPLS)", RFC 4202, October 2005. 768 [RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support 769 of Generalized Multi-Protocol Label Switching (GMPLS)", 770 RFC 4203, October 2005. 772 [RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label 773 Switching (GMPLS) Signaling Extensions for G.709 Optical 774 Transport Networks Control", RFC 4328, January 2006. 776 [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The 777 OSPF Opaque LSA Option", RFC 5250, July 2008. 779 [RFC5339] Le Roux, JL. and D. Papadimitriou, "Evaluation of Existing 780 GMPLS Protocols against Multi-Layer and Multi-Region 781 Networks (MLN/MRN)", RFC 5339, September 2008. 783 9.2. Informative References 785 [G.709-v1] 786 ITU-T, "Interface for the Optical Transport Network 787 (OTN)", G.709 Recommendation (and Amendment 1), 788 February 2001. 790 [G.709-v2] 791 ITU-T, "Interface for the Optical Transport Network 792 (OTN)", G.709 Recommendation (and Amendment 1), 793 March 2003. 795 [G.709-v3] 796 ITU-T, "Rec G.709, version 3", approved by ITU-T on 797 December 2009. 799 [G.872-am2] 800 ITU-T, "Amendment 2 of G.872 Architecture of optical 801 transport networks for consent", consented by ITU-T on 802 June 2010. 804 [OTN-FWK] F.Zhang, D.Li, H.Li, S.Belotti, "Framework for GMPLS and 805 PCE Control of G.709 Optical Transport Networks", work in 806 progress draft-ietf-ccamp-gmpls-g709-framework-00, April 807 2010. 809 Authors' Addresses 811 Sergio Belotti (editor) 812 Alcatel-Lucent 813 Via Trento, 30 814 Vimercate 815 Italy 817 Email: sergio.belotti@alcatel-lucent.com 819 Pietro Vittorio Grandi 820 Alcatel-Lucent 821 Via Trento, 30 822 Vimercate 823 Italy 825 Email: pietro_vittorio.grandi@alcatel-lucent.com 827 Daniele Ceccarelli (editor) 828 Ericsson 829 Via A. Negrone 1/A 830 Genova - Sestri Ponente 831 Italy 833 Email: daniele.ceccarelli@ericsson.com 835 Diego Caviglia 836 Ericsson 837 Via A. Negrone 1/A 838 Genova - Sestri Ponente 839 Italy 841 Email: diego.caviglia@ericsson.com 843 Fatai Zhang 844 Huawei Technologies 845 F3-5-B R&D Center, Huawei Base 846 Shenzhen 518129 P.R.China Bantian, Longgang District 847 Phone: +86-755-28972912 849 Email: zhangfatai@huawei.com 850 Dan Li 851 Huawei Technologies 852 F3-5-B R&D Center, Huawei Base 853 Shenzhen 518129 P.R.China Bantian, Longgang District 854 Phone: +86-755-28973237 856 Email: danli@huawei.com