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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