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Contreras 3 Internet-Draft Telefonica 4 Intended status: Informational P. Demestichas 5 Expires: May 6, 2021 WINGS 6 J. Tantsura 7 Apstra, Inc. 8 November 2, 2020 10 IETF Network Slice Intent 11 draft-contreras-nmrg-transport-slice-intent-04 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 IETF network 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 May 6, 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. IETF network slice intent . . . . . . . . . . . . . . . . . . 3 56 3. Foundation of IETF network slice intents . . . . . . . . . . 3 57 4. Mechanisms for translating IETF network 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 network slices at transport level (referred as IETF network 83 slices) providing the necessary connectivity to the rest of 84 components of the end-to-end slice, e.g., mobile packet core slice. 86 For a definition of an IETF network slice refer to 87 [I-D.nsdt-teas-ietf-network-slice-definition]. The following 88 paragraph is directly taken from it: "An IETF Network Slice is a 89 logical network topology connecting a number of endpoints with a set 90 of shared or dedicated network resources, that are used to satisfy 91 specific Service Level Objectives (SLOs)." 93 Intent is a high-level, declarative goal that operates at the level 94 of a network and services it provides, not individual devices. It is 95 used to define outcomes and high-level operational goals. 97 In consequence, it seems very convenient to apply the intent-based 98 mechanisms for the provision of IETF network slices, providing the 99 adequate level of abstraction towards the transport network control 100 and management planes. 102 This document leverages current industry trends in the definition of 103 end-to-end network slices. The final objective is to describe 104 intents that can be used to flexibly declare the operational aspects 105 and goals of an IETF network slice, meaning that the customer could 106 declare what kind of IETF network slice is needed (the outcome) and 107 not how to achieve the goals of the IETF network slice. 109 2. IETF network slice intent 111 As stated in [I-D.irtf-nmrg-ibn-concepts-definitions], "Intent is a 112 declaration of operational goals that a network should meet and 113 outcomes that the network is supposed to deliver, without specifying 114 how to achieve them. Those goals and outcomes are defined in a 115 manner that is purely declarative - they specify what to accomplish, 116 not how to achieve it." 118 When applied to transport networks, this implies that an intent for 119 IETF network slices should provide the necessary abstraction with 120 respect to implementation details, including the final devices (or 121 resources) involved, and be focused on the characteristics and 122 performance expectations related to it. 124 With that intent it can be expected that the intent based system can 125 fulfill and assure the requested IETF network slice, triggering 126 initial configurations at the time of initial provisioning and 127 corrective actions during the IETF network slice lifetime. 129 3. Foundation of IETF network slice intents 131 The industrial interest around 5G is accelerating network deployments 132 and operational changes. 134 With this respect, the GSMA has been developing a universal blueprint 135 that can be used by any vertical customer to request the deployment 136 of a network slice instance (NSI) based on a specific set of service 137 requirements. Such a blueprint is a network slice descriptor called 138 Generic Slice Template (GST) [GSMA]. The GST contains multiple 139 attributes that can be used to characterize a network slice. A 140 particular template filled with values generates a specific Network 141 Slice Type(NEST). 143 Such templates refer to the end-to-end network slice, including the 144 transport part. Despite the fact that some of the values would not 145 have applicability for the transport network, others do. An analysis 146 of the relevant attributes is performed in 147 [I-D.contreras-teas-slice-nbi]. 149 According to 3GPP propositions [TS28.541], an upper 3GPP Management 150 System interacts with the transport network for establishing the 151 necessary slices at the transport level. Such interaction can be 152 expected to happen using the IETF network slice intent, described to 153 an intent-based system (IBS) in the transport network part. Then, 154 according to the intent lifecycle in 155 [I-D.irtf-nmrg-ibn-concepts-definitions], the IBS, after recognizing 156 the intent, will proceed to translate it in order to interact with a 157 IETF network slice controller by using a NBI as proposed in 158 [I-D.contreras-teas-slice-nbi]. 160 4. Mechanisms for translating IETF network slice intents 162 This section describes approaches for implementing mechanisms to 163 translate IETF network slice intents. 165 4.1. Translation approaches and interaction with the upper systems 167 A suite of mechanisms will be required to allow instantiation of the 168 user's intent into a IETF network slice. In order to be able to 169 deliver an end2end Intent driven slice - a well defined set of 170 context aware attributes that allow unambiguous instantiation of the 171 intent should be agreed upon. A combination of a structured set of 172 attributes communicated between an IBN and an upper layer system with 173 user input would allow an IBN to have intent modeled and reason about 174 its completeness/validity. Translation approaches and interaction 175 with the upper systems might benefit from Natural Language Processing 176 (NLP) technics that are needed for enabling high level expression of 177 requirements found missing. The goal would be to identify and 178 classify the answers for as many fields as possible from the Generic 179 Slice Template (GST), based on the free text / speech provided by the 180 user. As it is highly unlikely that the minimum set of fields to 181 properly define an IETF network slice (geo-temporal characteristics, 182 performance characteristics, SLO and SLA properties) will be 183 fulfilled in this first step, a follow up two-step approach might 184 need to be implemented. 186 o The minimum missing fields from the GST have to be identified and 187 appropriate questions have to be generated (e.g. based on a pool 188 of available questions correlated with each field, or based on AI 189 approaches). 191 o An iterative interrogation phase will be initiated towards the 192 user using the previously generated questions, until the user 193 provides all the missing information, so the intent can be modeled 194 accordingly. 196 Interaction with the user and higher-up systems can potentially be 197 further improved by utilizing Machine Learning techniques. 199 4.2. Intent-based system suite 201 In order to consolidate on the set of devices, technologies and 202 resources to be used, a combination of deterministic or stochastic 203 computation approaches will be needed. Deterministic approaches will 204 rely on mathematical models and respective algorithms. Stochastic 205 approaches will rely on technologies like machine learning. Their 206 goal will be to learn from experience, so as to optimize future 207 decisions from the viewpoint of speed and reliability. The target of 208 learning will be related to the service behavior and to the 209 anticipated network status in the area and time period of the service 210 provision. 212 5. Security Considerations 214 To be done. 216 6. IANA Considerations 218 This draft does not include any IANA considerations 220 7. References 222 [GSMA] "Generic Network Slice Template, version 3.0", NG.116 , 223 May 2020. 225 [I-D.contreras-teas-slice-nbi] 226 Contreras, L., Homma, S., and J. Ordonez-Lucena, "IETF 227 Network Slice use cases and attributes for Northbound 228 Interface of controller", draft-contreras-teas-slice- 229 nbi-03 (work in progress), October 2020. 231 [I-D.irtf-nmrg-ibn-concepts-definitions] 232 Clemm, A., Ciavaglia, L., Granville, L., and J. Tantsura, 233 "Intent-Based Networking - Concepts and Definitions", 234 draft-irtf-nmrg-ibn-concepts-definitions-02 (work in 235 progress), September 2020. 237 [I-D.nsdt-teas-ietf-network-slice-definition] 238 Rokui, R., Homma, S., Makhijani, K., Contreras, L., and J. 239 Tantsura, "Definition of IETF Network Slices", draft-nsdt- 240 teas-ietf-network-slice-definition-00 (work in progress), 241 October 2020. 243 [TS28.541] 244 "TS 28.541 Management and orchestration; 5G Network 245 Resource Model (NRM); Stage 2 and stage 3 (Release 16) 246 V16.2.0.", 3GPP TS 28.541 V16.2.0 , September 2019. 248 Acknowledgments 250 This work has been partly funded by the European Commission through 251 the H2020 project 5G-EVE (Grant Agreement no. 815074). 253 Contributors 255 Kostas Tsagkaris, Kostas Trichias, Vassilis Foteinos, and Thanasis 256 Gkiolias (all from WINGS ICT Solutions) have also contributed to this 257 work. 259 Authors' Addresses 261 Luis M. Contreras 262 Telefonica 263 Ronda de la Comunicacion, s/n 264 Sur-3 building, 3rd floor 265 Madrid 28050 266 Spain 268 Email: luismiguel.contrerasmurillo@telefonica.com 269 URI: http://lmcontreras.com/ 271 Panagiotis Demestichas 272 WINGS ICT Solutions 273 Greece 275 Email: pdemest@wings-ict-solutions.eu 277 Jeff Tantsura 278 Apstra, Inc. 280 Email: jefftant.ietf@gmail.com