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Contreras 3 Internet-Draft Telefonica 4 Intended status: Informational P. Demestichas 5 Expires: January 27, 2021 WINGS 6 J. Tantsura 7 Apstra, Inc. 8 July 26, 2020 10 Transport Slice Intent 11 draft-contreras-nmrg-transport-slice-intent-03 13 Abstract 15 Slicing at the transport network is expected to be offered as part of 16 end-to-end network slices, fostered by the introduction of new 17 services such as 5G. This document explores the usage of intent 18 technologies for requesting transport slices. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on January 27, 2021. 37 Copyright Notice 39 Copyright (c) 2020 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Transport slice intent . . . . . . . . . . . . . . . . . . . 3 56 3. Foundation of transport slice intents . . . . . . . . . . . . 3 57 4. Mechanisms for translating transport slice intents . . . . . 4 58 4.1. Translation approaches and interaction with the upper 59 systems . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 4.2. Intent-based system suite . . . . . . . . . . . . . . . . 5 61 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 62 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 63 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6 65 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 6 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 68 1. Introduction 70 Network slicing is emerging as the future model for service offering 71 in telecom operator networks. Conceptually, network slicing provides 72 a customer with an apparent dedicated network built on top of logical 73 (i.e. virtual) and/or physical functions and resources supported by a 74 shared infrastructure, provided by one or more telecom operators. 76 The concept of network slicing has been largely fostered by the 77 advent of 5G services that are expected to be deployed on top of 78 different kind of slices, each built to support specific 79 characteristics (extreme low latency, high bandwidth, etc). 81 As part of an end-to-end network slice it is expected to have a 82 number of transport network slices providing the necessary 83 connectivity to the rest of components of the end-to-end slice, e.g., 84 mobile packet core slice. 86 For a definition of a transport slice refer to 87 [I-D.nsdt-teas-transport-slice-definition]. The following paragraph 88 is directly taken from it: "A transport slice is built based on a 89 request from a higher operations system. The interface to higher 90 operations systems should express the needed connectivity in a 91 technology-agnostic way, and slice customers do not need to recognize 92 concrete configurations based on the technologies (e.g being more 93 declarative than imperative). The request to instantiate a transport 94 slice is represented with some indicators such as SLO, and 95 technologies are selected and managed accordingly." 96 Intent is a high-level, declarative goal that operates at the level 97 of a network and services it provides, not individual devices. It is 98 used to define outcomes and high-level operational goals. 100 In consequence, it seems very convenient to apply the intent-based 101 mechanisms for the provision of transport network slices, providing 102 the adequate level of abstraction towards the transport network 103 control and management planes. 105 This document leverages current industry trends in the definition of 106 end-to-end network slices. The final objective is to describe 107 intents that can be used to flexibly declare the operational aspects 108 and goals of a transport network slice, meaning that the customer 109 could declare what kind of transport slice is needed (the outcome) 110 and not how to achieve the goals of the transport slice. 112 2. Transport slice intent 114 As stated in [I-D.irtf-nmrg-ibn-concepts-definitions], "Intent is a 115 declaration of operational goals that a network should meet and 116 outcomes that the network is supposed to deliver, without specifying 117 how to achieve them. Those goals and outcomes are defined in a 118 manner that is purely declarative - they specify what to accomplish, 119 not how to achieve it." 121 When applied to transport networks, this implies that an intent for 122 transport slices should provide the necessary abstraction with 123 respect to implementation details, including the final devices (or 124 resources) involved, and be focused on the characteristics and 125 performance expectations related to it. 127 With that intent it can be expected that the intent based system can 128 fulfill and assure the requested transport network slice, triggering 129 initial configurations at the time of initial provisioning and 130 corrective actions during the transport slice lifetime. 132 3. Foundation of transport slice intents 134 The industrial interest around 5G is accelerating network deployments 135 and operational changes. 137 With this respect, the GSMA has been developing a universal blueprint 138 that can be used by any vertical customer to request the deployment 139 of a network slice instance (NSI) based on a specific set of service 140 requirements. Such a blueprint is a network slice descriptor called 141 Generic Slice Template (GST) [GSMA]. The GST contains multiple 142 attributes that can be used to characterize a network slice. A 143 particular template filled with values generates a specific Network 144 Slice Type(NEST). 146 Such templates refer to the end-to-end network slice, including the 147 transport part. Despite the fact that some of the values would not 148 have applicability for the transport network, others do. An analysis 149 of the relevant attributes is performed in 150 [I-D.contreras-teas-slice-nbi]. 152 According to 3GPP propositions [TS28.541], an upper 3GPP Management 153 System interacts with the transport network for establishing the 154 necessary slices at the transport level. Such interaction can be 155 expected to happen using the transport slice intent, described to an 156 intent-based system (IBS) in the transport network part. Then, 157 according to the intent lifecycle in 158 [I-D.irtf-nmrg-ibn-concepts-definitions], the IBS, after recognizing 159 the intent, will proceed to translate it in order to interact with a 160 transport slice controller by using a NBI as proposed in 161 [I-D.contreras-teas-slice-nbi]. 163 4. Mechanisms for translating transport slice intents 165 This section describes approaches for implementing mechanisms to 166 translate transport slice intents. 168 4.1. Translation approaches and interaction with the upper systems 170 A suite of mechanisms will be required to allow instantiation of the 171 user's intent into a transport slice. In order to be able to deliver 172 an end2end Intent driven slice - a well defined set of context aware 173 attributes that allow unambiguous instantiation of the intent should 174 be agreed upon. A combination of a structured set of 175 attributes communicated between an IBN and an upper layer system with 176 user input would allow an IBN to have intent modeled and reason about 177 its completeness/validity. Translation approaches and interaction 178 with the upper systems might benefit from Natural Language Processing 179 (NLP) technics that are needed for enabling high level expression of 180 requirements found missing. The goal would be to identify and 181 classify the answers for as many fields as possible from the Generic 182 Slice Template (GST), based on the free text / speech provided by the 183 user. As it is highly unlikely that the minimum set of fields to 184 properly define a transport slice (geo-temporal characteristics, 185 performance characteristics, SLO and SLA properties) will be 186 fulfilled in this first step, a follow up two-step approach might 187 need to be implemented. 189 o The minimum missing fields from the GST have to be identified and 190 appropriate questions have to be generated (e.g. based on a pool 191 of available questions correlated with each field, or based on AI 192 approaches). 194 o An iterative interrogation phase will be initiated towards the 195 user using the previously generated questions, until the user 196 provides all the missing information, so the intent can be modeled 197 accordingly. 199 Interaction with the user and higher-up systems can potentially be 200 further improved by utilizing Machine Learning techniques. 202 4.2. Intent-based system suite 204 In order to consolidate on the set of devices, technologies and 205 resources to be used, a combination of deterministic or stochastic 206 computation approaches will be needed. Deterministic approaches will 207 rely on mathematical models and respective algorithms. Stochastic 208 approaches will rely on technologies like machine learning. Their 209 goal will be to learn from experience, so as to optimize future 210 decisions from the viewpoint of speed and reliability. The target of 211 learning will be related to the service behavior and to the 212 anticipated network status in the area and time period of the service 213 provision. 215 5. Security Considerations 217 To be done. 219 6. IANA Considerations 221 This draft does not include any IANA considerations 223 7. References 225 [GSMA] "Generic Network Slice Template, version 3.0", NG.116 , 226 May 2020. 228 [I-D.contreras-teas-slice-nbi] 229 Contreras, L., Homma, S., and J. Ordonez-Lucena, 230 "Considerations for defining a Transport Slice NBI", 231 draft-contreras-teas-slice-nbi-01 (work in progress), 232 March 2020. 234 [I-D.irtf-nmrg-ibn-concepts-definitions] 235 Clemm, A., Ciavaglia, L., Granville, L., and J. Tantsura, 236 "Intent-Based Networking - Concepts and Definitions", 237 draft-irtf-nmrg-ibn-concepts-definitions-01 (work in 238 progress), March 2020. 240 [I-D.nsdt-teas-transport-slice-definition] 241 Rokui, R., Homma, S., Makhijani, K., and L. Contreras, 242 "IETF Definition of Transport Slice", draft-nsdt-teas- 243 transport-slice-definition-02 (work in progress), April 244 2020. 246 [TS28.541] 247 "TS 28.541 Management and orchestration; 5G Network 248 Resource Model (NRM); Stage 2 and stage 3 (Release 16) 249 V16.2.0.", 3GPP TS 28.541 V16.2.0 , September 2019. 251 Acknowledgments 253 This work has been partly funded by the European Commission through 254 the H2020 project 5G-EVE (Grant Agreement no. 815074). 256 Contributors 258 Kostas Tsagkaris, Kostas Trichias, Vassilis Foteinos, and Thanasis 259 Gkiolias (all from WINGS ICT Solutions) have also contributed to this 260 work. 262 Authors' Addresses 264 Luis M. Contreras 265 Telefonica 266 Ronda de la Comunicacion, s/n 267 Sur-3 building, 3rd floor 268 Madrid 28050 269 Spain 271 Email: luismiguel.contrerasmurillo@telefonica.com 272 URI: http://lmcontreras.com/ 274 Panagiotis Demestichas 275 WINGS ICT Solutions 277 Greece 279 Email: pdemest@wings-ict-solutions.eu 281 Jeff Tantsura 282 Apstra, Inc. 284 Email: jefftant.ietf@gmail.com