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Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 CCAMP Working Group I. Busi (Ed.) 2 Internet-Draft Huawei 3 Intended status: Informational D. King (Ed.) 4 Expires: August, 2017 Lancaster University 5 February 7, 2017 7 A Service YANG Model for Connection-oriented Transport Networks 8 draft-tnbidt-ccamp-transport-nbi-use-cases-00 10 Abstract 12 Transport network domains, including Optical Transport Network (OTN) 13 and Wavelength Division Multiplexing (WDM) networks, are typically 14 deployed based on a single vendor or technology platforms. They are 15 often managed using proprietary interfaces to dedicated Element 16 Management Systems (EMS), Network Management Systems (NMS) and 17 increasingly Software Defined Network (SDN) controllers. 19 A well-defined open interface to each domain management system or 20 controller is required for network operators to facilitate control 21 automation and orchestrate end-to-end services across multi-domain 22 networks. These functions may enabled using standardized data models 23 (e.g. YANG), and appropriate protocol (e.g., RESTCONF). 25 This document describes the key use cases and requirements for 26 transport network control and management. It reviews proposed and 27 existing IETF transport network data models, their applicability, 28 and highlights gaps and requirements. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on August 7, 2017. 47 Copyright Notice 49 Copyright (c) 2017 IETF Trust and the persons identified as the 50 document authors. All rights reserved. This document is subject 51 to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF 52 Documents (http://trustee.ietf.org/license-info) in effect on the 53 date of publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. 57 Table of Contents 59 1. Introduction.................................................2 60 2. Conventions used in this document............................3 61 3. Use Case 1: Single-domain with single-layer..................3 62 3.1. Reference Network.......................................3 63 3.1.1. Single Transport Domain - OTN Network..............3 64 3.1.2. Single Domain - ROADM Network......................3 65 3.2. Topology Abstractions...................................6 66 3.3. Service Configuration...................................7 67 3.3.1. ODU Transit........................................7 68 3.3.2. EPL over ODU.......................................8 69 3.3.3. Other OTN Client Services..........................8 70 3.3.4. EVPL over ODU......................................9 71 3.3.5. EVPLAN and EVPTree Services........................9 72 3.3.6. Virtual Network Services...........................9 73 3.4. Multi-functional Access Links...........................9 74 4. Use Case 2: Single-domain with multi-layer...................9 75 5. Use Case 3: Multi-domain with single-layer...................9 76 6. Use Case 4: Multi-domain and multi-layer.....................9 77 7. Security Considerations......................................9 78 8. IANA Considerations..........................................9 79 9. References...................................................9 80 9.1. Normative References....................................10 81 9.2. Informative References..................................10 82 10. Acknowledgments.............................................10 83 Authors' Addresses..............................................11 85 1. Introduction 87 A common open interface to each domain controller/management system 88 is pre-requisite for network operators to control multi-vendor and 89 multi-domain networks and enable also service provisioning 90 coordination/automation. This can be achieved by using standardized 91 YANG models, used together with an appropriate protocol (e.g., 92 RESTCONF). 94 This document assumes a reference architecture, including interfaces, 95 based on the Abstraction and Control of Traffic-Engineered Networks 96 (ACTN), defined in [ACTN-Frame]. 98 The focus of the current version is on the MPI (interface between 99 the Multi Domain Service Coordinator (MDSC) and a Physical Network 100 Controller (PNC), controlling a transport network domain). 102 The relationship between the current IETF YANG models and the type of 103 ACTN interfaces can be found in [ACTN-YANG]. 105 The ONF Technical Recommendations for Functional Requirements 106 for the transport API, may be found in [ONF TR-527]. 107 Furthermore, ONF transport API multi-layer examples may be 108 found in [ONF GitHub]. 110 This document describes use cases that could be used for analyzing 111 the applicability of the existing models defined by the IETF for 112 transport networks 114 Considerations about the CMI (interface between the Customer Network 115 Controller (CNC) and the MDSC) are for further study. 117 2. Conventions used in this document 119 For discussion in future revisions of this document. 121 3. Use Case 1: Single-domain with single-layer 123 3.1. Reference Network 125 The current considerations discussed in this document are 126 based on the following reference networks: 128 - single transport domain: OTN network 130 It is expected that future revisions of the document will 131 include additional reference networks. 133 3.1.1. Single Transport Domain - OTN Network 135 Figure 1 shows the network physical topology composed of a 136 single-domain transport network providing transport services to an 137 IP network through five access links. 139 ................................................ 140 : IP domain : 141 : .............................. : 142 : : ........................ : : 143 : : : : : : 144 : : : S1 -------- S2 ------ C-R4 : 145 : : : / | : : : 146 : : : / | : : : 147 : C-R1 ------ S3 ----- S4 | : : : 148 : : : \ \ | : : : 149 : : : \ \ | : : : 150 : : : S5 \ | : : : 151 : C-R2 -----+ / \ \ | : : : 152 : : : \ / \ \ | : : : 153 : : : S6 ---- S7 ---- S8 ------ C-R5 : 154 : : : / : : : 155 : C-R3 -----+ : : : 156 : : : Transport domain : : : 157 : : : : : : 158 :........: :......................: :........: 160 Figure 1 Reference network for Use Case 1 162 The IP and transport (OTN) domains are respectively composed by five 163 routers C-R1 to C-R5 and by eight ODU switches S1 to S8. The 164 transport domain acts as a transit domain providing connectivity to 165 the IP layer. 167 The behavior of the transport domain is the same whether the 168 ingress/egress nodes in the IP domain, supporting an IP service, are 169 directly attached to the transport domain or there are other routers 170 in between the ingress/egress nodes of the IP domain and the routers 171 directly attached to the transport network. 173 +-----+ 174 | CNC | 175 +-----+ 176 | 177 |CMI I/F 178 | 179 +-----------------------+ 180 | MDSC | 181 +-----------------------+ 182 | 183 |MPI I/F 184 | 185 +-------+ 186 | PNC | 187 +-------+ 188 | 189 ----- 190 ( ) 191 ( OTN ) 192 ( Physical ) 193 ( Network ) 194 ( ) 195 ----- 197 Figure 2 Controlling Hierarchy for Use Case 1 199 The mapping of the client IP traffic on the physical link between the 200 routers and the transport network is made in the IP routers only and 201 is not controlled by the transport PNC and is transparent to the 202 transport nodes. 204 The control plane architecture follows the ACTN architecture and 205 framework document [ACTN-Frame]. The Client Controller act as a 206 client with respect to the Multi-Domain Service Coordinator (MDSC) 207 via the Controller-MDSC Interface (CMI). The MDSC is connected to a 208 plurality of Physical Network Controllers (PNCs), one for each 209 domain, via a MDSC-PNC Interface (MPI). Each PNC is responsible 210 only for the control of its domain and the MDSC is the only entity 211 capable of multi-domain functionalities as well as of managing the 212 inter-domain links. The key point of the whole ACTN framework is 213 detaching the network and service control from the underlying 214 technology and help the customer express the network as desired 215 by business needs. Therefore care must be taken to keep minimal 216 dependency on the CMI (or no dependency at all) with respect to 217 the network domain technologies. The MPI instead requires some 218 specialization according to the domain technology. 220 In this section, we address the case of an IP and a Transport PNC 221 having respectively an IP a Transport MPI. The interface within 222 the scope of this document is the Transport MPI while the IP 223 Network MPI is out of its scope and considerations about the CMI 224 are for further study. 226 3.2. Topology Abstractions 228 Abstraction is defined in [RFC7926] as: 230 Abstraction is the process of applying policy to the available TE 231 information within a domain, to produce selective information that 232 represents the potential ability to connect across the domain. 233 Thus, abstraction does not necessarily offer all possible 234 connectivity options, but presents a general view of potential 235 connectivity according to the policies that determine how the 236 domain's administrator wants to allow the domain resources to be 237 used. 239 [TE-Topo] describes YANG models for TE-network abstraction. 241 [ACTN-Abstraction] provides the context of topology abstraction in 242 the ACTN architecture and discusses a few alternatives for the 243 methods of abstraction for both packet and optical networks. This 244 is an important consideration since the choice of the abstraction 245 method impacts protocol design and the information it carries. 247 According to [ACTN-Abstraction], there are three types of topology: 249 o White topology: This is a case where the PNC provides the actual 250 network topology to the MDSC without any hiding or filtering. In 251 this case, the MDSC has the full knowledge of the underlying 252 network topology and as such there is no need for the MDSC to 253 send a path computation request to the PNC. The computation 254 burden will fall on the MDSC to find an optimal end-to-end path 255 and optimal per domain paths. 257 o Black topology: The entire domain network is abstracted as a 258 single virtual node with the access/egress links without 259 disclosing any node internal connectivity information. 261 o Grey topology: This abstraction level is between black topology 262 and white topology from a granularity point of view. This is 263 basically abstraction of TE tunnels for all pairs of border 264 nodes. 266 We may further differentiate from a perspective of how to 267 abstract internal TE resources between the pairs of border nodes: 269 - Grey topology type A: border nodes with a TE links between 270 them in a full mesh fashion. 272 - Grey topology type B: border nodes with some internal 273 abstracted nodes and abstracted links. 275 For single-domain with single-layer use-case, the white topology may 276 be disseminated from the PNC to the MDSC in most cases. There may be 277 some exception to this in the case where the underlay network may 278 have complex optical parameters which do not warrant the distribution 279 of such details to the MDSC. In such case, the topology disseminated 280 from the PNC to the MDSC may not have the entire TE information but a 281 streamlined TE information. This case would incur another action from 282 the MDSC's standpoint when provisioning a path. 284 The MDSC may make a path compute request to the PNC in order to 285 verify the feasibility of the estimated path before making the final 286 provisioning request to the PNC, as outlined in [Path-Compute]. 288 Topology abstraction for the CMI is for further study (to be 289 addressed in future revisions of this document). 291 3.3. Service Configuration 293 In the following use cases, the Multi Domain Service Coordinator 294 (MDSC) needs to be capable to request service connectivity from the 295 transport Physical Network Controller (PNC) to support IP routers 296 connectivity. The type of services could depend of the type of 297 physical links (e.g. OTN link, ETH link or SDH link) between the 298 routers and transport network. 300 As described in section 3.1.1, the control of different adaptations 301 inside IP routers, C-Ri (PKT -> foo) and C-Rj (foo -> PKT), are 302 assumed to be performed by means that are not under the control of, 303 and not visible to, transport PNC. Therefore, these mechanisms are 304 outside the scope of this document. 306 3.3.1. ODU Transit 308 This use case assumes that the physical link interconnecting IP 309 routers and transport network is an OTN link. 311 The physical/optical interconnection is supposed to be a 312 pre-configured and not exposed via MPI to MDSC. 314 If we consider the case of a 10Gb IP link between C-R1 to C-R3, 315 we need to instantiate an ODU2 end-to-end connection between C-R1 316 and C-R3, crossing transport nodes S3, S5, and S6. 318 The traffic flow between C-R1 and C-R3 can be summarized as: 320 C-R1 (PKT -> ODU2), S3 (ODU2), S5 (ODU2), S6 (ODU2), 321 C-R3 (ODU2 -> PKT) 323 The MDSC should be capable via MPI i/f to request the setup of ODU2 324 transit service with enough information that can permit transport 325 PNC to instantiate and control the ODU2 segment through nodes S3, 326 S5, S6. 328 3.3.2. EPL over ODU 330 This use case assumes that the physical link interconnecting IP 331 routers and transport network is an Ethernet link. 333 If we consider the case of a 10Gb IP link between C-R1 to C-R3, we 334 need to instantiate an EPL service between C-R1 and C-R3 supported 335 by an ODU2 end-to-end connection between S3 and S6, crossing 336 transport node S5. 338 The traffic flow between C-R1 and C-R3 can be summarized as: 340 C-R1 (PKT -> ETH), S3 (ETH -> ODU2), S5 (ODU2), 341 S6 (ODU2 -> ETH), C-R3 (ETH-> PKT) 343 The MDSC should be capable via MPI i/f to request the setup of EPL 344 service with enough information that can permit transport PNC to 345 instantiate and control the ODU2 end-to-end connection through nodes 346 S3, S5, S6, as well as the adaptation functions inside S3 and S6: 347 S3&S6 (ETH -> ODU2) and S9&S6 (ODU2 -> ETH). 349 3.3.3. Other OTN Client Services 351 [ITU-T G.709-2016] defines mappings of different client layers into 352 ODU. Most of them are used to provide Private Line services over 353 an OTN transport network supporting a variety of types of physical 354 access links (e.g., Ethernet, SDH STM-N, Fibre Channel, 355 InfiniBand,). 357 This use case assumes that the physical links interconnecting IP 358 routers and transport network are any one of these possible 359 options. 361 If we consider the case of a 10Gb IP link between C-R1 to C-R3 362 using SDH physical links, we need to instantiate an STM-64 Private 363 Line service between C-R1 and C-R3 supported by an ODU2 end-to-end 364 connection between S3 and S6, crossing transport node S5. 366 The traffic flow between C-R1 and C-R3 can be summarized as: 368 C-R1 (PKT -> STM-64), S3 (STM-64 -> ODU2), S5 (ODU2), 369 S6 (ODU2 -> STM-64), C-R3 (STM-64 -> PKT) 371 The MDSC should be capable via MPI i/f to request the setup of an 372 STM-64 Private Line service with enough information that can permit 373 transport PNC to instantiate and control the ODU2 end-to-end 374 connection through nodes S3, S5, S6, as well as the adaptation 375 functions inside S3 and S6: S3&S6 (STM-64 -> ODU2) and S9&S3 376 (STM-64 -> PKT). 378 3.3.4. EVPL over ODU 380 For future revision. 382 3.3.5. EVPLAN and EVPTree Services 384 For future revision. 386 3.3.6. Virtual Network Services 388 For future revision 390 3.4. Multi-functional Access Links 392 For future revision 394 4. Use Case 2: Single-domain with multi-layer 396 For future revision 398 5. Use Case 3: Multi-domain with single-layer 400 For future revision 402 6. Use Case 4: Multi-domain and multi-layer 404 For future revision 406 7. Security Considerations 408 For further study 410 8. IANA Considerations 412 This document requires no IANA actions. 414 9. References 415 9.1. Normative References 417 [RFC7926] Farrel, A. et al., "Problem Statement and Architecture for 418 Information Exchange between Interconnected Traffic-Engineered 419 Networks", BCP 206, RFC 7926, July 2016. 421 [ITU-T G.709-2016] ITU-T Recommendation G.709 (06/16), "Interfaces 422 for the optical transport network", June 2016. 424 [ACTN-Frame] Ceccarelli, D., Lee, Y. et al., "Framework for 425 Abstraction and Control of Transport Networks", 426 draft-ietf-teas-actn-framework, work in progress. 428 [ACTN-Abstraction] Lee, Y. et al., " Abstraction and Control of 429 TE Networks (ACTN) Abstraction Methods", 430 draft-lee-teas-actn-abstraction, work in progress. 432 9.2. Informative References 434 [TE-Topo] Liu, X. et al., "YANG Data Model for TE Topologies", 435 draft-ietf-teas-yang-te-topo, work in progress. 437 [ACTN-YANG] Zhang, X. et al., "Applicability of YANG models for 438 Abstraction and Control of Traffic Engineered Networks", 439 draft-zhang-teas-actn-yang, work in progress. 441 [Path-Compute] Busi, I., Belotti, S. et al., " Yang model for 442 requesting Path Computation", draft-busibel-teas-yang-path- 443 computation, work in progress. 445 [ONF TR-527] ONF Technical Recommendation TR-527, "Functional 446 Requirements for Transport API", June 2016 448 [ONF GitHub] ONF Open Transport (SNOWMASS) 449 https://github.com/OpenNetworkingFoundation/Snowmass- 450 ONFOpenTransport 452 10. Acknowledgments 454 The authors would like to thank all members of the Transport NBI 455 Design Team involved in the definition of use cases, gap analysis 456 and guidelines for using the IETF YANG models at the Northbound 457 Interface (NBI) of a Transport SDN Controller. 459 The authors would like to thank Xian Zhang, Anurag Sharma, Michael 460 Scharf, Karthik Sethuraman, Oscar Gonzalez de Dios, Tara Cummings 461 and Hans Bjursrom, for having initiated work on gap analysis for 462 transport NBI and having provided foundations work for the 463 development of this document. 465 Authors' Addresses 467 Italo Busi (Editor) 468 Huawei 469 Email: italo.busi@huawei.com 471 Daniel King (Editor) 472 Lancaster University 473 Email: d.king@lancaster.ac.uk 475 Sergio Belotti 476 Nokia 477 Email: sergio.belotti@nokia.com 479 Gianmarco Bruno 480 Ericsson 481 Email: gianmarco.bruno@ericsson.com 483 Young Lee 484 Huawei 485 Email: leeyoung@huawei.com 487 Victor Lopez 488 Telefonica 489 Email: victor.lopezalvarez@telefonica.com 491 Carlo Perocchio 492 Ericsson 493 Email: carlo.perocchio@ericsson.com 495 Haomian Zheng 496 Huawei 497 Email: zhenghaomian@huawei.com