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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 nfvrg L. Wang 3 Internet-Draft L. Geng 4 Intended status: Informational China Mobile 5 Expires: January 3, 2019 July 02, 2018 7 Review of Network Slicing Research in Diverse Standards 8 draft-wang-nfvrg-network-slice-diverse-standards-00 10 Abstract 12 As one of the significant technology in 5G, there are diverse 13 industry communities and standard organizations dedicated in a 14 research of Network Slicing, such as IETF, 3GPP, GSMA, ETSI, etc.. 15 These organizations and communities not only standardize network 16 slicing architecture, management, requirements and so on, but also 17 individually focus on specifying network slicing in their own ways, 18 offering diverse specifications of it. Aiming at research on a 19 overall review of network slicing standard, this document discuss 20 diverse standards in various organizations and communities, 21 furthermore, analyzing the emphasis and difference between them. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on January 3, 2019. 40 Copyright Notice 42 Copyright (c) 2018 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (https://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. Overview of Network Slicing Standard Progress . . . . . . . . 3 60 4. Detailed Diverse Network Slicing Standards . . . . . . . . . 4 61 4.1. IETF . . . . . . . . . . . . . . . . . . . . . . . . . . 4 62 4.1.1. Network Slicing in IETF . . . . . . . . . . . . . . . 4 63 4.1.2. Information Model . . . . . . . . . . . . . . . . . . 5 64 4.2. 3GPP . . . . . . . . . . . . . . . . . . . . . . . . . . 6 65 4.2.1. Network Slicing in 5G . . . . . . . . . . . . . . . . 6 66 4.2.2. Network Slice Operation Procedure . . . . . . . . . . 7 67 4.3. ETSI . . . . . . . . . . . . . . . . . . . . . . . . . . 9 68 4.4. GSMA . . . . . . . . . . . . . . . . . . . . . . . . . . 9 69 5. Conclusion:Different Understanding and Emphasis of Each 70 Organizations . . . . . . . . . . . . . . . . . . . . . . . . 9 71 6. Informative References . . . . . . . . . . . . . . . . . . . 10 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 74 1. Introduction 76 With the rapid development of 5G technology research and successful 77 emergence of 5G market, network slicing is becoming one of 78 significant technologies of 5G. The mechanism of network slicing is 79 that divide common physical network infrastructure into diverse 80 isolated virtual network resources to meet the high level demands 81 from different vertical industry. With network slicing, providers 82 are able to offer customized service to users in terms of bandwidth, 83 latency, security and so on. Network slicing mechanism enables 5G to 84 integrate diverse network resources and multi-domain technologies, to 85 meet various demands from vertical industry, offering the best-effort 86 network service. For instance, to achieve both determined latency 87 and security requirements from some industry services, network 88 slicing is likely to apply TSN[tsn] and blockchain technologies to 89 satisfy the requirement. Meanwhile, network resources such as high 90 bandwidth and dedicated network tunnel can be supplied here to meet 91 the demands as well which are all integrate in this network slice. 93 As the key feature of 5G, the concept of network slicing is discussed 94 in related standard organizations and communities. 3GPP release 95 network slicing standard of architecture in specification 96 [TR23.501]and management&orchestration in specification [TR28.801] . 98 3GPP also specify requirement, use cases and other related features 99 of network slicing in different work groups. Also, being so 100 important to network technology progress, network slicing has gotten 101 a lot of attention and heated discussion in IETF. Several drafts are 102 released and discussed in netslicing and COMS mailing list which will 103 be talked in the following sections. Besides, there are other 104 organizations are doing research in network slicing, such as European 105 Telecommunications Standards Institute (ETSI), Broadband Forum (BBF), 106 GSM Association (GSMA), etc. Each of them makes diverse definition 107 and concern different areas of network slicing definition. 109 It shows that network slicing has been defined by multiple Standards 110 Definition Organizations (SDOs) and communities. However, as a 111 diversity of mission of each, the meaning and understanding of the 112 network slicing concept are different from each other and there is no 113 common definition. In the following part of documents, an overview 114 of network slicing research aspect will be discussed. Furthermore, 115 the emphasis and difference between each organization is analyzed as 116 well. This is aimed at giving out clear viewpoints of network 117 slicing understanding from these organizations. 119 2. Terminology 121 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 122 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 123 document are to be interpreted as described in [RFC2119]. 125 PLMN, Public Land Mobile Network, is a network that is established 126 and operated by providers for the specific purpose of providing land 127 mobile telecommunications services to the public. 129 NSSAI, Network Slice Selection Assistance Information. NSSAI 130 provided by the Serving PLMN during a Registration procedure, 131 indicating the S-NSSAIs values the UE could use in the Serving PLMN 132 for the current registration area. 134 S-NSSAI, Single Network Slice Selection Assistance Information. 135 S-NSSAI identify a network slice. 137 3. Overview of Network Slicing Standard Progress 139 In this section, an overview of network slicing standard progress 140 will be given out. 142 IETF Network slicing is discussed in terms of specification of 143 terminology, architecture[draft-geng-coms-architecture-02], use 144 cases[draft-qiang-coms-use-cases-00], problem statement and other 145 aspects related to network slicing. To map the gap between 146 technology-agnostic network slicing service requirements and 147 specific implementation technologies, a technology independent 148 information model is created. Furthermore, aiming at converging 149 bottom-up and top-down approaches on a technology-independent 150 common management plane, COMS (Common Operation and Management on 151 network Slices) is defined and described 152 here[draft-geng-coms-architecture-02]. 154 3GPP Acknowledging network slicing as significant component of 5G 155 process, 3GPP dedicated in making a thorough specification of 156 network slicing concept since the very early time when they 157 started considering 5G technology. Network slicing is specified 158 in SA1 (requirements), SA2 (architecture), SA3 (security) and SA5 159 (network management) respectively, in which architecture and 160 management will mainly be described the next paragraph. 162 ETSI ETSI analyses network slicing use cases defined in other SDOs 163 and industry fora in Report on Network Slicing Support with ETSI 164 NFV Architecture Framework [ETSI_GR_NFV-EVE], and give the 165 description that how to map the use cases to the NFV architecture 166 and concepts. 168 GSMA GSMA give the Concept of network slicing from a business way 169 and indicate that how network slicing can serve and support 5G 170 network in its report [GSMA-An-Introduction-to-Network-Slicing] 172 4. Detailed Diverse Network Slicing Standards 174 4.1. IETF 176 4.1.1. Network Slicing in IETF 178 In [draft-geng-netslices-architecture-02] , end to end network slice 179 is defined as a cross-domain network slice which may consist of 180 access network, transport network, (mobile) core network. The 181 concept here of network slice is expanded to a wider area and 182 comprises of several functional components. Driven by the multiple 183 requirements from users, network slice instance may include several 184 service components that each of which may require a set of network 185 resources and attributes in form of a network slice. 187 Network Slicing Management and Orchestration is comprised of: 189 Template Management: A complete description of the structure, 190 configuration and the plans/work flows for how to instantiate and 191 control the network slice instance during its life cycle. 193 NS Repository: A policy to describe how user select network slice 194 or how multi-slice instance associated with one network slice. 196 Life cycle management and monitoring : Network slicing and slice 197 instance must be full life cycle managed and monitored. 199 E2E Orchestration: E2E Slices Orchestration and its functionality 200 which can be a)Coordinating a number of interrelated resources, 201 b)Autonomically control of slice life cycle management, 202 c)Autonomically coordinate and trigger of slice elasticity and 203 placement of logical resources in slices, d)Coordinates and (re)- 204 configure logical resources. 206 Domain Orchestration: In heterogeneous environment, network 207 slicing is expected to orchestrate multiple domain technologies 208 and resources to gain the most effective, dynamic and automatic 209 functions. 211 NS Manager: Manager manages all access permissions and all 212 interaction between a Network Slice and external functions which 213 are specific for each network slice instance. 215 Resource Registration: Responsible for the management of exposed 216 capability of the network infrastructure. 218 Under network slicing management and orchestration, the resource 219 management which can be physical, logical and virtual resources will 220 be mapped to the requirements and Capabilities users demands to 221 create the related network slice instance. The Capabilities of 222 network slicing includes reclusiveness, protection, elasticity, 223 extensibility, safety and isolation. 225 4.1.2. Information Model 227 However, sometimes customers, being not able to know or not familiar 228 with the underlying networking resources and technologies, expect a 229 technology-agnostic interface. A information model here is in demand 230 to fill the gap between technology-agnostic network slicing service 231 requirements and specific implementation technologies. 233 The information model for network slicing here is required to offer 234 the capability that describe the entities that compose a network 235 slice, their functions and the mechanism how they serve the 236 corresponding network slice. The information model provide the 237 connectivity of undying technologies from providers and customers 238 requirements, and gives out a clear and complete informal diagrams of 239 network slices entities and technologies in different domains. 241 4.2. 3GPP 243 Here we only disscuss the architecture and management of Network 244 slicing in 3GPP, which are mostly related to [TR23.501] and 245 [TR28.801] 247 4.2.1. Network Slicing in 5G 249 In 3GPP [TR23.501], a network slice is defined as an end to end 250 logical communication network, within a Public Land Mobile Network 251 (PLMN) and includes the Core Network (CN) Control Plane, User Plane 252 Network Functions and 5G Access Network (AN). 254 A singal UE(User Equipment) may be served by multiple slices 255 simultaneously through a single RAN. Correspondingly, network slices 256 may vary for supported features and network functions optimisations 257 because of different S-NSSAIs with different Slice/Service Types. So 258 provider may select to deploy multiple network slices, but offering 259 same service feature, to serve a group of UEs. 261 S-NSSAI, delivering identification and selection information of a 262 network slice, is comprised of a Slice/Service type (SST) which 263 refers to the expected Network Slice behaviour in terms of features 264 and services and a Slice Differentiator (SD) which is optional 265 information that complements the Slice/Service type(s) to 266 differentiate amongst multiple Network Slices of the same Slice/ 267 Service type. Network Slice instance can be associated with one or 268 more S-NSSAIs, and an S-NSSAI can be associated with one or more 269 Network Slice instances.SST value represents 3 service types that are 270 eMBB (enhanced Mobile Broadband), URLLC (ultra- Reliable Low Latency 271 Communications) and MIoT (Massive IoT) respectively. 273 Figure 1 is a network slicing architecture in 5G. For one network 274 slice instance, UE selects a network slice by requesting a S-NSSAI 275 via RAN (This will be given details in next section), and core 276 network responds to allocate the corresponding slice. 278 Network Slice +----------------------------------------------------------------------+ 279 Instance | +-----+ +-----+ +----------|CORE|--------------+ | 280 +------------+ | | | | | Transmission | +----+ +----+ +----+ +----+ | | 281 | eMBB +--------------+ |UE +---(R)AN +-------------------+ |UPF | |AMF | |SMF | |PCF | | |slice1 282 +------------+ +--+ | | | | Bearing Network | | | | | | | | |... | 283 | | | | | | | +----+ +----+ +----+ +----+ | | 284 +------------+ | | +-----+ +-----+ +------------------------------+ | 285 | URLLC +-----------+ ++--------+--------------------------+----------------------------------+ 286 +------------+ +--+ | | | | | | | 287 | | +-----+ +-----+ +-------------------------+ | slice2 288 +-------------+ | | | 289 | MIoT +--------+ ++------+--+-----+------------------+------------------------+-----+---+ 290 +-------------+ | | | | | | | | 291 | +------+ +-----+ +------------------------+ |slice3 292 | | 293 +---------------------------------------------------------------------+ 295 Figure 1 297 4.2.2. Network Slice Operation Procedure 299 The Network slicing operation procedure starts from UE registration, 300 in which the selection of Network Slice instances for a UE is 301 triggered by the first contacted Access and Mobility Management 302 Function (AMF). After AMF selected by the AN receives the UE 303 Registration request, UE signals a requested NSSAI to AMF, and AMF is 304 expected to determine whether it can serve the UE by verifying 305 whether the S-NSSAI(s) in the Requested NSSAI are permitted based on 306 the Subscribed S-NSSAIs. If this case is permitted, AMF query the 307 Network Slice Selection Function (NSSF), with Requested NSSAI, 308 mapping of Requested NSSAI to Configured NSSAI. The NSSF returns to 309 the current AMF the Allowed NSSAI for the applicable Access Type(s) 310 and UE, after receiving an Allowed NSSAI from the serving AMF, will 311 store it. 313 As the one of the most important goals of network slicing 314 configuration, the Protocol Data Unit (PDU) Session Establishment in 315 a Network Slice to a DN allows data transmission in a Network Slice. 316 The data transmission works after a PDU session to a Data Network is 317 established in a Network Slice. Each PDU session corresponds to one 318 core network slice and one RAN slice specifically.Here AMF is common 319 to network slices serving the UE, but SMF and UPF are specific to 320 each slice they associated to. 322 +---------+ 323 | UE | 324 +----+----+ 325 NSSAI | 326 +----+----+ 327 | RAN | 328 +---------+ 329 |RAN choose AMF with NSSAI 330 NSSAI | 331 +--------------------------+-----------------------------+ 332 | AMF queries the NSSF | 333 | +--------+ with Requested NSSAI--------+ | 334 | | +-------------------------^ NSSF | | 335 | | AMF <-------------------------+ | | 336 | +--------NSSF returns to the +--------+ | 337 | +-------+Allowed NSSAI | 338 | | NRF | | 339 | +-------+ | 340 +--------------------------+------+----------------------+ 341 | | 342 | +-------++ 343 +-------------+------------+ | 344 | | | 345 | +-----+ +-----+ +-----+ +-++ 346 | | | | | | | | | 347 | | | | | | | | | 348 | |SMF | |UPF | | PCF ...| | 349 | | | | | | | | | 350 | | | | | | | | | 351 | | | | | | | | | 352 | +-----+ +-----+ +-----+ | | 353 | | | 354 +---+-------+--------------+ | 355 | | | 356 | | | 357 +------------+------------+ 358 | | 359 +--+-+ | 360 |DN1 | | 361 +----++-+----+ 362 | DN2 | 363 +------+ 365 Figure 2 Network Slice Operation 367 4.3. ETSI 369 Rather than defining the standard of network slicing as well as other 370 organizations, ETSI focuses on the mapping of the network slicing to 371 NFV concept and describe how NFV architecture support it under the 372 standards of diverse organization such as 3GPP. 374 Under the 3GPP defination of network slicing, ETSI defines NFV-NS 375 that represent the virtualized resources for the slice subnet and 376 their connectivity to physical resources. ETSI also describe Os-Ma- 377 NFvo interface point that offer the interaction between the 3GPP 378 slicing management and NFV-MANO, which is also related to a couple of 379 management determination from NSMF and NSSMF. 381 4.4. GSMA 383 In [GSMA-An-Introduction-to-Network-Slicing], GSMA give the Concept 384 of network slicing from the point of view of business customers that 385 "Network slicing is the embodiment of the concept of running multiple 386 logical networks as virtually independent business operations on a 387 common physical infrastructure in an efficient and economical way." 388 And they define that customisable network capabilities include data 389 speed, quality, latency, reliability, security, and services. It is 390 also mentioned that different operators can share the same network 391 slice in GSMA description. 393 5. Conclusion:Different Understanding and Emphasis of Each 394 Organizations 396 Based on the above description of network slicing and its entities 397 from different organizations, it is not hard to find that they 398 provide a different understanding of network slicing concept and have 399 their emphasis of research on it: 401 In 3GPP, network slice is deployed in RAN, UPF and CN for a mobile 402 network. Network slice instance is created by the cooperation 403 between RAN and CN, which is more like a customized sliced 404 function in core network. But the connectivity part, transmission 405 network between CN and RAN is not sliced. 407 IETF anticipates to define an broader applied end-to-end network 408 slicing for not only mobile network, but also other networks forms 409 which may not includes CN or RAN. Therefore, the transmission 410 network is considered as part of network slice resource/instance 411 which can be sliced as well. This may ask for a orchestration of 412 multiple domain technologies in transmission network and a 413 information model to expose the relating tech capabilities. 415 ETSI mainly focuses on the mapping between NFV function and 416 network slice based on the network slicing definition from current 417 organizations, while GSMA define network slicing in a general and 418 business way. 420 All of the descriptions from diverse organizations is attempting to 421 give a comprehensive and typical standard for network slicing. 423 6. Informative References 425 [draft-geng-coms-architecture-02] 426 "COMS Architecture", . 429 [draft-geng-netslices-architecture-02] 430 "Network Slicing Architecture", 431 . 434 [draft-qiang-coms-netslicing-information-model-02] 435 "Technology Independent Information Model for Network 436 Slicing", . 439 [draft-qiang-coms-use-cases-00] 440 "The Use Cases of Common Operation and Management of 441 Network Slicing", . 444 [ETSI_GR_NFV-EVE] 445 "Report on Network Slicing Support with ETSI NFV 446 Architecture Framework Disclaimer", 447 . 450 [GSMA-An-Introduction-to-Network-Slicing] 451 , . 455 [I-D.boucadair-connectivity-provisioning-protocol] 456 Boucadair, M., Jacquenet, C., Zhang, D., and P. 457 Georgatsos, "Connectivity Provisioning Negotiation 458 Protocol (CPNP)", draft-boucadair-connectivity- 459 provisioning-protocol-15 (work in progress), December 460 2017. 462 [RFC2119] "Key words for use in RFCs to Indicate Requirement 463 Levels". 465 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 466 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 467 DOI 10.17487/RFC5440, March 2009, 468 . 470 [TR23.501] 471 "System Architecture for the 5G System", 472 . 475 [TR28.801] 476 "Telecommunication management;Study on management and 477 orchestration of network slicing for next generation 478 network", 479 . 482 [tsn] "Time-Sensitive Networking (TSN) Task Group", 483 . 485 Authors' Addresses 487 Lei Wang 488 China Mobile 489 Beijing 100053 490 China 492 Email: jifengyiwl@163.com 494 Liang Geng 495 China Mobile 496 Beijing 100053 497 China 499 Email: gengliang@chinamobile.com