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rfc:rfc9316



Internet Research Task Force (IRTF) C. Li Request for Comments: 9316 China Telecom Category: Informational O. Havel ISSN: 2070-1721 A. Olariu

                                                   Huawei Technologies
                                                     P. Martinez-Julia
                                                                  NICT
                                                              J. Nobre
                                                                 UFRGS
                                                              D. Lopez
                                                       Telefonica, I+D
                                                          October 2022
                       Intent Classification

Abstract

 Intent is an abstract, high-level policy used to operate a network.
 An intent-based management system includes an interface for users to
 input requests and an engine to translate the intents into the
 network configuration and manage their life cycle.
 This document mostly discusses the concept of network intents, but
 other types of intents are also considered.  Specifically, this
 document highlights stakeholder perspectives of intent, methods to
 classify and encode intent, and the associated intent taxonomy; it
 also defines relevant intent terms where necessary, provides a
 foundation for intent-related research, and facilitates solution
 development.
 This document is a product of the IRTF Network Management Research
 Group (NMRG).

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 This document is a product of the Internet Research Task Force
 (IRTF).  The IRTF publishes the results of Internet-related research
 and development activities.  These results might not be suitable for
 deployment.  This RFC represents the consensus of the Network
 Management Research Group of the Internet Research Task Force (IRTF).
 Documents approved for publication by the IRSG are not candidates for
 any level of Internet Standard; see Section 2 of RFC 7841.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 https://www.rfc-editor.org/info/rfc9316.

Copyright Notice

 Copyright (c) 2022 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (https://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.

Table of Contents

 1.  Introduction
   1.1.  Research Activities
   1.2.  Standards and Open-Source Activities
   1.3.  Scope
 2.  Abbreviations
 3.  Definitions
 4.  Abstract Intent Requirements
   4.1.  What is intent?
   4.2.  Intent Solutions and Intent Users
   4.3.  Benefits of Intents for Different Stakeholders
   4.4.  Intent Types That Need to Be Supported
 5.  Functional Characteristics and Behavior
   5.1.  Abstracting Intent Operation
   5.2.  Intent User Types
   5.3.  Intent Scope
   5.4.  Intent Network Scope
   5.5.  Intent Abstraction
   5.6.  Intent Life Cycle
   5.7.  Autonomous Driving Levels
 6.  Intent Classification
   6.1.  Intent Classification Methodology
   6.2.  Intent Taxonomy
   6.3.  Intent Classification for Carrier Solution
     6.3.1.  Intent Users and Intent Types
     6.3.2.  Intent Categories
     6.3.3.  Intent Classification Example
   6.4.  Intent Classification for Data Center Network Solutions
     6.4.1.  Intent Users and Intent Types
     6.4.2.  Intent Categories
     6.4.3.  Intent Classification Example
   6.5.  Intent Classification for Enterprise Solution
     6.5.1.  Intent Users and Intent Types
     6.5.2.  Intent Categories
 7.  Conclusions
 8.  Security Considerations
 9.  IANA Considerations
 10. Informative References
 Acknowledgments
 Contributors
 Authors' Addresses

1. Introduction

 The vision of intent-based networks has attracted a lot of attention
 because it promises to simplify the management of networks by human
 operators.  This is done by simply specifying what should happen on
 the network without giving any instructions on how to do it.  This
 promise caused many researcher-led activities and telecom companies
 to start researching this new vision and many Standards Development
 Organizations (SDOs) to propose different intent frameworks.
 This document proposes an intent classification methodology and an
 intent taxonomy.  The scope of these proposals is to ensure a common
 understanding in the research community in terms of what the intent
 users, intent types, or intent solutions, etc., are for specific
 scenarios that are being considered.
 The document represents the consensus of the Network Management
 Research Group (NMRG).  It has been reviewed extensively by the
 Research Group (RG) members who are actively involved in the research
 and development of the technology covered by this document.  It is
 not an IETF product and is not a standard.

1.1. Research Activities

 Intent-based networking is an active research topic spanning across
 different areas that could benefit from an intent classification and
 taxonomy.
 Some examples include:
  • intent expression and recognition ([Bezahaf21], [Bezahaf19],

[Jacobs18]). The use of a common classification could provide

    consistency in the understanding of the various forms of intent
    expressions being proposed and investigated.
  • the orchestration of cognitive autonomous radio access networks

(RANs) [Banerjee21] where intents are classified based on their

    content.
  • intent network verification [Tian19], where the authors are

working to propose new intent language.

 Furthermore, this document is already proving to be extremely
 relevant to the research community as it has been used as the basis
 for proposing self-generated Intent-based systems [Bezahaf19], for
 advancing Virtual Network Function (VNF) placement solutions based on
 Internet-Based Networks (IBNs) that rely on defining user intent
 profiles corresponding to abstract network services [Leivadeas21],
 for improving existing solutions in provisioning intent-based
 networks, for proposing new approaches to service management
 [Davoli21], and even for defining grammars for users to specify the
 high-level requirements for blockchain selection in the form of
 intent [Padovan20].  As well, the document has been mentioned in
 surveys addressing the topic of intelligent intent-based autonomous
 networks [Mehmood21] [Szilagyi21].
 This document also describes an example on how this proposal has been
 successfully applied in an academic environment [POC-IBN] by
 researchers in the area of Software-Defined Networking / Network
 Function Virtualization (SDN/NFV) for defining the scope of their
 project.  The specific problem addressed by researchers is how to
 apply intent concepts at different levels that correspond to
 different stakeholders.
 The IEEE Communications Society Technical Committee on Network
 Operation and Management (IEEE-CNOM), IRTF Network Management
 Research Group, and IFIP WG6.6 have developed a taxonomy for network
 and service management [IFIP-NSM] that is used by the research
 community in network management and operations to structure the
 research area through a well-defined set of keywords and to improve
 quality of reviews in submissions to journals, conferences, and
 workshops.  The proposed intent taxonomy may be contributed as an
 extension to this taxonomy for intent-driven management.

1.2. Standards and Open-Source Activities

 Several SDOs and open-source projects, such as the IRTF NMRG, Open
 Networking Foundation (ONF) [ONF] / Open Network Operating System
 (ONOS) [ONOS], European Telecommunications Standards Institute (ETSI)
 / Experiential Networked Intelligence (ENI), and TMF with its
 autonomous networks, have proposed intents for defining a set of
 network operations to execute in a declarative manner.
 More recently, the IRTF NMRG is working on "Intent-Based Networking -
 Concepts and Definitions" [RFC9315].  This document clarifies the
 concept of "Intent" and provides an overview of the functionality
 that is associated with it.  The goal is to contribute towards a
 common and shared understanding of terms, concepts, and functionality
 that can be used as the foundation to guide further definition of
 associated research and engineering problems and their solutions.
 The present document, together with [RFC9315], aims to become the
 foundation for future intent-related topic discussions regarding the
 NMRG.
 The SDOs usually come up with their own way of specifying an intent
 and their own understanding of what an intent is.  Additionally, each
 SDO defines a set of terms and level of abstraction, its intent
 users, and the applications and usage scenarios.
 However, most intent approaches proposed by SDOs share the same
 features:
  • It must be declarative in nature, meaning that an intent user

specifies the goal on the network without specifying how to

    achieve that goal.
  • It must be vendor agnostic in the sense that it abstracts the

network capabilities or the network infrastructure from the intent

    user, and it can be ported across different platforms.
  • It must provide an easy-to-use interface, which simplifies the

interaction of the intent users with the intent system through the

    usage of familiar terminology or concepts.
  • It should be able to detect and resolve intent conflicts, which

include, for example, static (compile-time) conflicts and dynamic

    (run-time) conflicts.

1.3. Scope

 The focus of this document is on the definition of criteria enabling
 the categorization of intents from viewpoint of the stakeholders.
 Concepts and definitions related to IBN are provided in [RFC9315].
 This document mostly addresses intents in the context of network
 intents; however, other types of intents are not excluded, as
 presented in Sections 4.4 and 6.2.
 It is impossible to fully differentiate intents only by the common
 characteristics followed by concepts, terms, and intentions.  This
 document clarifies what an intent represents for different
 stakeholders through a classification on various dimensions, such as
 solutions, intent users, and intent types.  This classification
 ensures common understanding among all participants and is used to
 determine the scope and priority of individual projects, proof of
 concepts (PoCs), research initiatives, or open-source projects.
 The scope of intent classification in this document includes
 solutions, intent users, and intent types; the initial classification
 table is made according to this scope.  The methodology presented can
 be used to update the classification tables by adding or removing
 different solutions, intent users, or intent types to cater to future
 scenarios, applications, or domains.

2. Abbreviations

 AI:  Artificial Intelligence
 CE:  Customer Equipment
 CFS:  Customer Facing Service
 CLI:  Command-Line Interface
 DB:  Database
 DC:  Data Center
 ECA:  Event Condition Action
 GBP:  Group-Based Policy
 GPU:  Graphics Processing Unit
 IBN:  Intent-Based Network
 NFV:  Network Function Virtualization
 O&M:  OAM & Maintenance
 ONF:  Open Networking Foundation
 ONOS:  Open Network Operating System
 PNF:  Physical Network Function
 QoE:  Quality of Experience
 RFS:  Resource Facing Service
 SDO:  Standards Development Organization
 SD-WAN:  Software-Defined Wide-Area Network
 SLA:  Service Level Agreement
 SUPA:  Simplified Use of Policy Abstractions
 VM:  Virtual Machine
 VNF:  Virtual Network Function

3. Definitions

 A common and shared understanding of terms and definitions related to
 IBN is provided in [RFC9315] as follows:
 Intent:  A set of operational goals (that a network should meet) and
    outcomes (that a network is supposed to deliver) defined in a
    declarative manner without specifying how to achieve or implement
    them.
 Intent-Based Network:  A network that can be managed using intent.
 Policy:  A set of rules that governs the choices in behavior of a
    system.
 Intent User:  A user that defines and issues the intent request to
    the intent-based management system.
 Other definitions relevant to this document, such as intent scope,
 intent network scope, intent abstraction, intent abstraction, and
 intent life cycle are available in Section 5.

4. Abstract Intent Requirements

 In order to understand the different intent requirements that would
 drive intent classification, we first need to understand what intent
 means for different intent users.

4.1. What is intent?

 The term "Intent" has become very widely used in the industry for
 different purposes; sometimes its use is not even in agreement with
 SDO-shared principles mentioned in Section 1.  [RFC9315] brings
 clarification with relation to what an intent is and how it
 differentiates from policies and services.
 Different stakeholders have different perspectives of the network;
 therefore, they have different intent requirements.  Their intent is
 sometimes technical, non-technical, abstract, or technology specific.
 Therefore, it is important to start a discussion in the industry and
 academic communities about what intent is for different solutions and
 intent users.  It is also imperative to try to propose some intent
 categories/classifications that could be understood by a wider
 audience.  This would help us define intent interfaces, domain-
 specific languages, and models.

4.2. Intent Solutions and Intent Users

 Intent types are defined by all aspects that are required to profile
 different requirements to easily distinguish between them.  However,
 in order to facilitate a clustered classification, we can focus on
 two aspects: the solution and intent user.  They can be considered to
 be the main keys to classify intents, as we can easily group
 requirements by solution and intent user.
 On the one hand, different solutions and intent users have different
 requirements, expectations, and priorities for intent-based
 networking.  Therefore, intent users require different intent types,
 depending on their context, since they participate in different use
 cases.  For instance, some intent users are more technical and
 require intents that expose more technical information.  Other intent
 users do not have knowledge of the network infrastructure and require
 intents that shield them from different networking concepts and
 technologies.
 The following are the solutions and intent users that intent-based
 networking needs to support:
         +============+=====================================+
         | Solutions  | Intent Users                        |
         +============+=====================================+
         | Carrier    | Network Operators, Service          |
         | Networks   | Designers / App Developers, Service |
         |            | Operators, Customers / Subscribers  |
         +------------+-------------------------------------+
         | DC         | Cloud Administrators, Underlay      |
         | Networks   | Network Administrators, Application |
         |            | Developers, Customers / Tenants     |
         +------------+-------------------------------------+
         | Enterprise | Enterprise Administrators,          |
         | Networks   | Application Developers, End Users   |
         +------------+-------------------------------------+
              Table 1: Intent Solutions and Intent Users
 These intent solutions and intent users represent a starting point
 for the classification and are expendable through the methodology
 presented in Section 6.1.
  • For carrier network scenarios, for example, if a customer/

subscriber wants to watch high-definition video, then the intent

    is to convert the video image to 1080p.
  • For DC network scenarios, administrators have their own clear

network intent such as load balancing. For all traffic flows that

    need NFV service chaining, they can restrict the maximum load of
    any VNF node / container below 50% and the maximum load of any
    network link below 70%.
  • For enterprise network scenarios, when hosting a video conference,

multiple remote accesses are required. An example of the intent

    from the network administrator is as follows: for any end user of
    this application, the arrival time of hologram objects of all the
    remote tele-presenters should be synchronized within 50 ms to
    reach the destination viewer for each conversation session.

4.3. Benefits of Intents for Different Stakeholders

 Current network APIs and CLIs are too complex because they are highly
 integrated with the low-level concepts exposed by networks.
 Customers, application developers, and end users must not be required
 to set IP addresses, VLANs, subnets, or ports, whereas operators may
 still want to have both more technical and network visibility.  All
 stakeholders would benefit from simpler interfaces, such as:
  • request gold VPN service between sites A, B, and C
  • provide CE redundancy for the customer sites
  • add access rules to the network service
 Operators and administrators manually troubleshoot and fix their
 networks and services.  They instead want to:
  • simplify and automate network operations
  • simplify definitions of network services
  • provide simple customer APIs for value-added services (operators)
  • be informed if the network or service is not behaving as requested
  • enable automatic optimization and correction for selected

scenarios

  • have systems that learn from historic information and behavior
 Currently, intent users cannot build their own services and policies
 without becoming technical experts and performing manual maintenance
 actions.  They instead want to be able to:
  • build their own network services with their own policies via

simple interfaces, without becoming networking experts

  • have their network services up and running based on intent and

automation only, without any manual actions or maintenance

4.4. Intent Types That Need to Be Supported

 Next to the intent solutions and intent users, another way to
 categorize the intent is through the intent types.  The following
 intent types and subtypes need to be supported in order to address
 the requirements from different solutions and intent users.
  • Customer service intent
  1. for customer self service with SLA
  1. for service operator orders
  • Network and underlay network service intent
  1. for service operator orders
  1. for intent-driven network configuration, verification,

correction, and optimization

  1. for intent created and provided by the underlay network

administrator

  • Network and underlay network intent
  1. for network configuration
  1. for automated life-cycle management of network configurations
  1. for network resources (switches, routers, routing, policies,

and underlay)

  • Cloud management intent
  1. for DC configuration, VMs, DB servers, and Application servers
  1. for communication between VMs
  • Cloud resource management intent
  1. for cloud resource life-cycle management (policy-driven self-

configuration and auto-scaling and recovery/optimization)

  • Strategy intent
  1. for security, QoS, application policies, traffic steering, etc.
  1. for configuring and monitoring policies, alarm generation for

non-compliance, and auto-recovery

  1. for design models and policies for network and network service

design

  1. for design workflows, models, and policies for operational task

intents

  • Operational task intents
  1. for network migration
  1. for device replacements
  1. for network software upgrades
  1. for automating any other tasks that operators/administrator

often perform

 It is important to mention all of the previously mentioned types and
 subtypes may affect other intents.  For example, operational task
 intent can modify many other intents.  The task itself is short
 lived, but the modification of other intents has an impact on their
 life cycle, so those changes must continue to be continuously
 monitored and self corrected/optimized.

5. Functional Characteristics and Behavior

 Intent can be used to operate immediately on a target (much like
 issuing a command) or whenever it is appropriate (e.g., in response
 to an event).  In either case, intent has a number of behaviors that
 serve to further organize its purpose, as described by the following
 subsections.

5.1. Abstracting Intent Operation

 The modeling of intents can be abstracted using the following three-
 tuple:
 {Context, Capabilities, Constraints}
  • Context grounds the intent and determines if it is relevant or not

for the current situation. Thus, context selects intents based on

    applicability.
  • Capabilities describe the functionality that the intent can

perform. Capabilities take different forms depending on the

    expressivity of the intent as well as the programming paradigm(s)
    used.
  • Constraints define any restrictions on the capabilities to be used

for that particular context.

 Metadata can be attached via strategy templates to each of the
 elements of the three-tuple and may be used to describe how the
 intent should be used and how it operates as well as prescribe any
 operational dependencies that must be taken into account.
 Although different intent categories share the same abstracted intent
 model, each category will have its own specific context,
 capabilities, and constraints.

5.2. Intent User Types

 Expanding on the introduction in Section 4.2, intent user types
 represent the intent users that define and issue the intent request.
 Depending on the intent solutions, there are specific intent users.
 Examples of intent users are customers, network operators, service
 operators, enterprise administrators, cloud administrators, underlay
 network administrators, or application developers.
  • Customers and end users do not necessarily know the functional and

operational details of the network that they are using.

    Furthermore, they lack skills to understand such details; in fact,
    such knowledge is typically not relevant to their job.  In
    addition, the network may not expose these details to its intent
    users.  This class of intent users focuses on the applications
    that they run and uses services offered by the network.  Hence,
    they want to specify policies that provide consistent behavior
    according to their business needs.  They do not have to worry
    about how the intents are deployed onto the underlying network and
    especially whether the intents need to be translated to different
    forms to enable network elements to understand them.
  • Application developers work in a set of abstractions defined by

their application and programming environment(s). For example,

    many application developers think in terms of objects (e.g., a
    VPN).  While this makes sense to the application developer, most
    network devices do not have a VPN object per se; rather, the VPN
    is formed through a set of configuration statements for that
    device in concert with configuration statements for the other
    devices that together make up the VPN.  Hence, the view of
    application developers matches the services provided by the
    network but may not directly correspond to other views of other
    intent users.
  • Network operators may have the knowledge of the underlying

network. However, they may not understand the details of the

    applications and services of customers.

5.3. Intent Scope

 Intents are used to manage the behavior of the networks they are
 applied to and all intents are applied within a specific scope, such
 as:
  • connectivity scope, if the intent creates or modifies a connection
  • security/privacy scope, if the intent specifies the security

characteristics of the network, customers, or end users

  • application scope, when the intent specifies the applications to

be affected by the intent request

  • QoS scope, when the intent specifies the QoS characteristics of

the network

 These intent scopes are expendable through the methodology presented
 in Section 6.1.

5.4. Intent Network Scope

 Regardless of the intent user type, their intent request affects the
 network, or network components, which are representing the intent
 targets.
 Thus, the intent network scope, or policy target as known in the area
 of declarative policy, can represent VNFs or PNFs, physical network
 elements, campus networks, SD-WANs, RANs, cloud edges, cloud cores,
 branches, etc.

5.5. Intent Abstraction

 Intent can be classified by whether it is necessary to feed back
 technical network information or non-technical information to the
 intent user after the intent is executed.  As well, intent
 abstraction covers the level of technical details in the intent
 itself.
  • Non-technical intent users do not care how the intent is executed

nor do they care about the details of the network. As a result,

    they do not need to know the configuration information of the
    underlying network.  They only focus on whether the intent
    execution result achieves the goal and the execution effect such
    as the quality of completion and the length of execution.  In this
    scenario, we refer to an abstraction without technical feedback.
  • Administrators, such as network administrators, perform intents,

such as allocating network resources, selecting transmission

    paths, handling network failures, etc.  They require multiple
    feedback indicators for network resource conditions, congestion
    conditions, fault conditions, etc., after execution.  In this
    case, we refer to an abstraction with technical feedback.
 As per the definition of "intent" provided in [RFC9315], lower-level
 intents are not considered to qualify as intents.  However, we kept
 this classification to identify any PoCs / Demos / Use Cases that
 still either require or implement a lower level of abstraction for
 intents.

5.6. Intent Life Cycle

 Intents can be classified into transient and persistent intents:
 Transient:  The intent has no life-cycle management.  As soon as the
    specified operation is successfully carried out, the intent is
    finished and can no longer affect the target object.
 Persistent:  The intent has life-cycle management.  Once the intent
    is successfully activated and deployed, the system will keep all
    relevant intents active until they are deactivated or removed.

5.7. Autonomous Driving Levels

 In different phases of the autonomous driving network [TMF-AUTO], the
 intents are different.  Depending on the Autonomous Network Level of
 the overall solution, we may have different intent requirements and
 types.  For example, at lower levels, the customer intent is:
  • automatically converted to configuration policies only while at

the higher levels,

  • covering the full life cycle,
  • converted to both configuration and monitoring policies, and
  • self assured using AI.
 Typical examples of autonomous driving networks level 0 to 5 are
 shown below.
 Level 0 - Traditional manual network:
    O&M personnel manually control the network and obtain network
    alarms and logs.
  1. No intent
 Level 1 - Partially automated network:
    Automated scripts are used to automate service provisioning,
    network deployment, and maintenance.  The network provides shallow
    perception of the network status and decision making suggestions.
  1. No intent
 Level 2 - Automated network:
    This entails the automation of most service provisioning, network
    deployment, and maintenance of a comprehensive perception of
    network status and local machine decision-making.
  1. simple intent on service provisioning
 Level 3 - Self-optimization network:
    This entails a deep awareness of network status and automatic
    network control, meeting requirements of intent users of the
    network.
  1. Intent based on network status cognition
 Level 4 - Partial autonomous network:
    In a limited environment, people do not need to participate in
    decision-making and networks can adjust themselves.
  1. Intent based on limited AI
 Level 5 - Autonomous network:
    In different network environments and network conditions, the
    network can automatically adapt and adjust to meet people's
    intentions.
  1. Intent based on AI

6. Intent Classification

 This section proposes an approach to intent classification that may
 help to classify mainstream intent-related demos/tools.
 The three classifications in this document have been proposed from
 scratch (following the methodology presented) through three
 iterations: one for a carrier network intent solution, one for a DC
 intent solution, and one for an enterprise intent solution.  For each
 intent solution, we identified the specific intent users and intent
 types.  Then, we further identified intent scope, network scope,
 abstractions, and life-cycle requirements.
 These classifications and the generated tables can be easily
 extended.  For example, for the DC intent solution, a new category
 "resource scope" is identified, and the classification table has been
 extended accordingly.
 In the future, as new scenarios, applications, and domains emerge,
 new classifications and taxonomies can be identified, following the
 proposed methodology.
 The intent classifications have been documented to the best of our
 knowledge at the time of writing.  Additional classifications will
 most likely come to light in the future.
 The output of the intent classification is the intent taxonomy
 introduced in the subsections of this section.
 Thus, the subsections of Section 6 introduce the proposed intent
 classification methodology, the consolidated intent taxonomy for
 three intent solutions, and the concrete examples of intent
 classifications for three different intent solutions (e.g., carrier
 network, data center, and enterprise) that were derived using the
 proposed methodology and can be filled in for PoCs, demos, research
 projects, or future documents.

6.1. Intent Classification Methodology

 This section describes the methodology used to derive the initial
 classification proposed in the document.  The proposed methodology
 can be used to create new intent classifications from scratch by
 analyzing the solution knowledge.  As well, the methodology can be
 used to update existing classification tables by adding or removing
 different solutions, intent users, or intent types in order to cater
 to future scenarios, applications, or domains.
           +------------------------------------------+
           |Solution Knowledge (requirements,         |
           |use cases, technologies, network, intent  |
           |users, intent requirements)               |
           +----------------+-------------------------+
                            | Input             Rx=Read
                            |                   Ux=Update (Add/Remove)
                   +--------V--------+
                   |1.Identify Intent|
                   |  Solution       +------------+
                   |                 |            |
                   +---------^-+-----+            |
                          R1 | | U1               |
 +---------------+ U8        | |    R2         +--v----------------+
 |8.Identify New +---------+ | |   +-----------> 2.Identify        |
 |  Categories   | R8      | | |   | U2        |   Intent          |
 |               <-------- | | |   | +---------+   User Types      |
 +--------^------+       | | | |   | |         +-------|-----------+
          |              | | | |   | |                 |
          |             ++-+-v-v---+-v-+               |
 +--------+------+ U7   |              | R3     +------v------------+
 |7.Identify     +------>   Intent     +--------> 3.Identify        |
 |  Life-Cycle   | R7   |Classification| U3     |   Type            |
 |  Requirements <------+              <--------+   of Intent       |
 +--------^------+      +^--^-+--^-+---+        +------|------------+
          |              || | |  | |                   |
          |              || | |  | |                   |
 +--------+-----+        || | |  | | R4        +-------v-----------+
 |6.Identify    | U6     || | |  | +-----------> 4.Identify        |
 |  Abstractions+---------| | |  |   U4        |   Intent          |
 |              <---------+ | |  +-------------+   Scope           |
 +-------^------+ R6        | |                +-------+-----------+
         |                  | |                        |
         |               U5 | |R5                      |
         |          +-------+-v--------+               |
         |          |5.Identify Network|               |
         +----------+  Scope           <---------------+
                    +------------------+
              Figure 1: Intent Classification Methodology
 The intent classification workflow starts from the solution
 knowledge, which can provide information on requirements, use cases,
 technologies used, network properties, intent users that define and
 issue the intent request, and requirements.  The following defines
 the steps to classify an intent:
 1.  Receive the information provided in the solution knowledge as
     input for identifying the intent solution (e.g., carrier,
     enterprise, and data center).  Intent solutions are reviewed
     against the existing classification and can either be used if
     present or added if not there; if not needed, they can be removed
     from the classification (R1-U1).
 2.  Identify the intent user types (e.g., customer, network
     operators, service operators, etc.).  Review the existing intent
     classification.  Then use the intent user type if present; add it
     if it is not there or remove it if not needed (R2-U2).
 3.  Identify the types of intent (e.g., network intent, customer
     service intent).  Review the existing classification and then
     use, add, or remove the intent type (R3-U3).
 4.  Identify the intent scopes (e.g., connectivity, application)
     based on the solution knowledge.  Then, review the existing
     classification.  Use, add, or remove the identified intent scope
     (R4-U4).
 5.  Identify the network scopes (e.g., campus, radio access).  Then,
     review the existing classification.  Either use, add, or remove
     the identified network scope (R5-U5).
 6.  Identify the abstractions (e.g., technical, non-technical).
     Then, review the existing classification and either use, add, or
     remove the abstractions (R6-U6).
 7.  Identify the life-cycle requirements (e.g., persistent,
     transient).  Then, review the existing classification.  Either
     use, add, or remove the life-cycle requirements (R7-U7).
 8.  Identify any new categories.  Use and add the newly identified
     categories.  New categories can be identified as new domains or
     applications emerge or as new areas of concern (e.g., privacy,
     compliance) arise that are not listed in the current methodology.

6.2. Intent Taxonomy

 The following taxonomy describes the various intent solutions, intent
 user types, intent types, intent scopes, network scopes,
 abstractions, and life cycles.  The taxonomy represents the output of
 the intent classification tables for each of the solutions addressed
 (i.e., carrier, data center, and enterprise solutions).
 The intent scope categories in Figure 2 are shared among the carrier,
 DC, and enterprise solutions.  The abbreviations (Cx) in Sections
 6.3.2 and 6.4.2 are introduced with the scope of fitting as column
 title in the following tables.
                                 +--------------------------------+
                             +-->|Carrier  Enterprise  Data Center|
                             |   +--------------------------------+
                             |   +--------------------------------+
                             |   |Customer/Subscriber/End User    |
               +----------+  |   |Network or Service Operator     |
             +>+Solution  +--+   |Application Developer           |
             | +----------+   +->|Enterprise Administrator        |
             |                |  |Cloud Administrator             |
             | +----------+   |  |Underlay Network Administrator  |
             +>+Intent    +---+  +--------------------------------+
             | |User      |      +--------------------------------+
             | |Type      |      |Customer Service Intent         |
             | +----------+      |Strategy Intent                 |
             | +----------+      |Network Service Intent          |
             +>+Intent    +----->|Underlay Network Service Intent |
    +------+ | |Type      |      |Network Intent                  |
    |Intent+-+ +----------+      |Underlay Network Intent         |
    +------+ |                   |Operational Task Intent         |
             | +----------+      |Cloud Management Intent         |
             +>+Intent    +---+  |Cloud Resource Management Intent|
             | |Scope     |   |  +--------------------------------+
             | +----------+   |  +--------------------------------+
             |                +->|Connectivity   Application  QoS |
             | +----------+      |Security/Privacy Storage Compute|
             +>+Network   +---+  +--------------------------------+
             | |Scope     |   |  +--------------------------------+
             | +----------+   |  |Radio Access      Branch        |
             |                +->|Transport Access  SD-WAN        |
             | +----------+      |Transport Aggr.   VNF      PNF  |
             +>+Abstrac-  +----+ |Transport Core    Physical      |
             | |tion      |    | |Cloud Edge        Logical       |
             | +----------+    | |Cloud Core        Campus        |
             | +----------+    | +--------------------------------+
             +>+Life      |    | +--------------------------------+
               |Cycle     +--+ +>|Technical         Non-Technical |
               +----------+  |   +--------------------------------+
                             |   +--------------------------------+
                             +-->|Persistent        Transient     |
                                 +--------------------------------+
                       Figure 2: Intent Taxonomy

6.3. Intent Classification for Carrier Solution

6.3.1. Intent Users and Intent Types

 This section addresses steps 1, 2, and 3 from Figure 1.  The
 following table describes the intent users in carrier solutions and
 intent types with their descriptions for different intent users.
 +=============+=============+=======================================+
 | Intent User | Intent Type | Intent Type Description               |
 +=============+=============+=======================================+
 | Customer/   | Customer    | Customer self service with SLA        |
 | Subscriber  | Service     | and value-added service.              |
 |             | Intent      |                                       |
 |             |             | Example: Always maintain a high       |
 |             |             | quality of service and high           |
 |             |             | bandwidth for gold-level              |
 |             |             | subscribers.                          |
 |             |             |                                       |
 |             |             | Operation statement: Measure the      |
 |             |             | network congestion status, give       |
 |             |             | different adaptive parameters to      |
 |             |             | stations of different priority;       |
 |             |             | thus, in a heavy load situation,      |
 |             |             | make the bandwidth of the high-       |
 |             |             | priority customers guaranteed.        |
 |             |             | At the same time, ensure the          |
 |             |             | overall utilization of the            |
 |             |             | system and improve the overall        |
 |             |             | throughput of the system.             |
 |             +-------------+---------------------------------------+
 |             | Strategy    | Customer designs models and           |
 |             | Intent      | policy intents to be used by          |
 |             |             | customer service intents.             |
 |             |             |                                       |
 |             |             | Example: Request reliable             |
 |             |             | service during peak traffic           |
 |             |             | periods for video-type apps.          |
 +-------------+-------------+---------------------------------------+
 | Network     | Network     | Service provided by the network       |
 | Operator    | Service     | service operator to the customer      |
 |             | Intent      | (e.g., the service operator).         |
 |             |             |                                       |
 |             |             | Example: Request network service      |
 |             |             | with delay guarantee for access       |
 |             |             | customer A.                           |
 |             +-------------+---------------------------------------+
 |             | Network     | Network operator requests             |
 |             | Intent      | network-wide (service underlay        |
 |             |             | or other network-wide                 |
 |             |             | configuration) or network-            |
 |             |             | resource configurations               |
 |             |             | (switches, routers, routing, or       |
 |             |             | policies).  Includes                  |
 |             |             | connectivity, routing, QoS,           |
 |             |             | security, application policies,       |
 |             |             | traffic steering policies, alarm      |
 |             |             | generation for non-compliance,        |
 |             |             | auto-recovery, etc.                   |
 |             |             |                                       |
 |             |             | Example: Request high priority        |
 |             |             | queuing for traffic of class A.       |
 |             +-------------+---------------------------------------+
 |             | Operational | Network operator requests             |
 |             | Task Intent | execution of any automated task       |
 |             |             | other than network service            |
 |             |             | intent and network intent (e.g.,      |
 |             |             | network migration, server             |
 |             |             | replacements, device                  |
 |             |             | replacements, or network              |
 |             |             | software upgrades).                   |
 |             |             |                                       |
 |             |             | Example: Request migration of         |
 |             |             | all services in network N to          |
 |             |             | backup path P.                        |
 |             +-------------+---------------------------------------+
 |             | Strategy    | Network operator designs models,      |
 |             | Intent      | policy intents, and workflows to      |
 |             |             | be used by network service            |
 |             |             | intents, network intents, and         |
 |             |             | operational task intents.             |
 |             |             | Workflows can automate any tasks      |
 |             |             | that the network operator often       |
 |             |             | performs in addition to network       |
 |             |             | service intents and network           |
 |             |             | intents.                              |
 |             |             |                                       |
 |             |             | Example: Ensure the load on any       |
 |             |             | link in the network is not            |
 |             |             | higher than 50%.                      |
 +-------------+-------------+---------------------------------------+
 | Service     | Customer    | Service operator's customer           |
 | Operator    | Service     | orders, customer service, or          |
 |             | Intent      | SLA.                                  |
 |             |             |                                       |
 |             |             | Example: Provide service S with       |
 |             |             | guaranteed bandwidth for              |
 |             |             | customer A.                           |
 |             +-------------+---------------------------------------+
 |             | Network     | Service operator's network            |
 |             | Service     | orders / network SLA.                 |
 |             | Intent      |                                       |
 |             |             | Example: Provide network              |
 |             |             | guarantees in terms of security,      |
 |             |             | low latency, and high bandwidth.      |
 |             +-------------+---------------------------------------+
 |             | Operational | Service operator requests             |
 |             | Task Intent | execution of any automated task       |
 |             |             | other than customer service           |
 |             |             | intent and network service            |
 |             |             | intent.                               |
 |             |             |                                       |
 |             |             | Example: Update service operator      |
 |             |             | portal platforms and their            |
 |             |             | software regularly.  Move             |
 |             |             | services from network operator 1      |
 |             |             | to network operator 2.                |
 |             +-------------+---------------------------------------+
 |             | Strategy    | Service operator designs models,      |
 |             | Intent      | policy intents, and workflows to      |
 |             |             | be used by customer service           |
 |             |             | intents, network service              |
 |             |             | intents, and operational task         |
 |             |             | intents.  Workflows can automate      |
 |             |             | any task that the service             |
 |             |             | operator often performs in            |
 |             |             | addition to network service           |
 |             |             | intents and network intents.          |
 |             |             |                                       |
 |             |             | Example: Request network service      |
 |             |             | guarantee to avoid network            |
 |             |             | congestion during special             |
 |             |             | periods such as Black Friday and      |
 |             |             | Christmas.                            |
 +-------------+-------------+---------------------------------------+
 | Application | Customer    | Customer service intent API           |
 | Developer   | Service     | provided to the application           |
 |             | Intent      | developers.                           |
 |             |             |                                       |
 |             |             | Example: API to request network       |
 |             |             | to watch HD video (4K/8K).            |
 |             +-------------+---------------------------------------+
 |             | Network     | Network service intent API            |
 |             | Service     | provided to the application           |
 |             | Intent      | developers.                           |
 |             |             |                                       |
 |             |             | Example: API to request network       |
 |             |             | service, monitoring, and traffic      |
 |             |             | grooming.                             |
 |             +-------------+---------------------------------------+
 |             | Network     | Network intent API provided to        |
 |             | Intent      | the application developers.           |
 |             |             |                                       |
 |             |             | Example: API to request network       |
 |             |             | resource configurations.              |
 |             +-------------+---------------------------------------+
 |             | Operational | Operational task intent API           |
 |             | Task Intent | provided to the application           |
 |             |             | developers.  This is for the          |
 |             |             | trusted internal operator /           |
 |             |             | service providers / customer          |
 |             |             | DevOps.                               |
 |             |             |                                       |
 |             |             | Example: API to request server        |
 |             |             | migrations.                           |
 |             +-------------+---------------------------------------+
 |             | Strategy    | Application developer designs         |
 |             | Intent      | models, policy, and workflows to      |
 |             |             | be used by customer service           |
 |             |             | intents, network service              |
 |             |             | intents, and operational task         |
 |             |             | intents.  This is for the             |
 |             |             | trusted internal operator /           |
 |             |             | service provider / customer           |
 |             |             | DevOps.                               |
 |             |             |                                       |
 |             |             | Example: API to design network        |
 |             |             | load-balancing strategies during      |
 |             |             | peak times.                           |
 +-------------+-------------+---------------------------------------+
          Table 2: Intent Classification for Carrier Solution

6.3.2. Intent Categories

 This subsection addresses steps 4 to 7 from Figure 1.  The following
 are the proposed categories:
 Intent Scope:  C1=Connectivity, C2=Security/Privacy, C3=Application,
    C4=QoS
 Network Scope:
                 Network Domain:  C1=Radio Access, C2=Transport
       Access, C3=Transport Aggregation, C4=Transport Core, C5=Cloud
       Edge, C6=Cloud Core
                 Network Function (NF) Scope:  C1=VNFs, C2=PNFs
 Abstraction (ABS):  C1=Technical (with technical feedback), C2=Non-
    technical (without technical feedback) (see Section 5.2).
 Life cycle (L-C):  C1=Persistent (full life cycle), C2=Transient
    (short lived)

6.3.3. Intent Classification Example

 This section contains an example of how the methodology described in
 Section 6.1 can be used in order to classify intents introduced in
 the "A Multi-Level Approach to IBN" PoC demonstration [POC-IBN].
 This PoC is led by academics carrying out research in the area of
 SDN/NFV, and the specific problem they are addressing is the
 application of the intent concept at different levels that correspond
 to different stakeholders.  For this research work, they considered
 two types of intents: slice intents and service chain intents.
 In this PoC [POC-IBN], a slice intent expresses a request for a
 network slice with two types of components: a set of top-layer
 virtual functions and a set of virtual switches and/or routers of L2/
 L3 VNFs.  A service chain intent expresses a request for a service
 operated through a chain of service components running in L4-L7
 virtual functions.
 Following the intent classification methodology described step by
 step in Section 6.1, the following can be derived:
 1.  The intent solution for both intents is carrier network.
 2.  The intent user type is network operator for the slice intent and
     service operator for the service chain intent.
 3.  The type of intent is a network service intent for the slice
     intent and a customer service intent for the service chain
     intent.
 4.  The intent scopes are connectivity and application.
 5.  The network scope is VNF, cloud edge, and cloud core.
 6.  The abstractions are with technical feedback for the slice intent
     and without technical feedback for the service chain intent.
 7.  The life cycle is persistent.
 The following table shows how to represent this information in a
 tabular form.  The "X" in the table refers to the slice intent; the
 "Y" in the table refers to the service chain intent.

+==========+===========+===========+=====+=================+=====+=====+

Intent Intent TypeIntent NF Network ABS L-C
User Scope ScopeScope
C1C2C3C4C1C2C1C2C3C4C5C6C1C2C1C2

+==========+===========+==+==+==+==+==+==+==+==+==+==+==+==+==+==+==+==+

Customer/ Customer
SubscriberService
Intent
Strategy
Intent

+———-+———–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+

Network Network X X X X X X
Operator Service
Intent
Network
Intent
Operational
Task Intent
Strategy
Intent

+———-+———–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+

Service Customer Y Y Y Y Y Y Y
Operator Intent
Network
Service
Intent
Op Task
Intent
Strategy
Intent

+———-+———–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+

App Customer
Developer Intent
Network
Service
Intent
Network
Intent
Op Task
Intent
Strategy
Intent

+———-+———–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+–+

   Figure 3: Intent Classification Example for Carrier Solution

6.4. Intent Classification for Data Center Network Solutions

6.4.1. Intent Users and Intent Types

 The following table describes the intent users in DC network
 solutions and intent types with their descriptions for different
 intent users.
 +===============+=============+====================================+
 | Intent User   | Intent Type | Intent Type Description            |
 +===============+=============+====================================+
 | Customer/     | Customer    | Customer self service via tenant   |
 | Tenants       | Service     | portal.                            |
 |               |             |                                    |
 |               |             | Example: Request GPU computing and |
 |               |             | storage resources to meet 10k      |
 |               |             | video surveillance services.       |
 |               +-------------+------------------------------------+
 |               | Strategy    | This includes models and policy    |
 |               | Intent      | intents designed by customers/     |
 |               |             | tenants to be reused later during  |
 |               |             | instantiation.                     |
 |               |             |                                    |
 |               |             | Example: Request dynamic computing |
 |               |             | and storage resources of the       |
 |               |             | service in special and daily       |
 |               |             | times.                             |
 +---------------+-------------+------------------------------------+
 | Cloud         | Cloud       | Configuration of VMs, DB Servers,  |
 | Administrator | Management  | app servers, and communication     |
 |               | Intent      | between servers and VMs.           |
 |               |             |                                    |
 |               |             | Example: Request connectivity      |
 |               |             | between VMs A, B, and C in network |
 |               |             | N1.                                |
 |               +-------------+------------------------------------+
 |               | Cloud       | Policy-driven self configuration   |
 |               | Resource    | and recovery/optimization.         |
 |               | Management  |                                    |
 |               | Intent      | Example: Request automatic life-   |
 |               |             | cycle management of VM cloud       |
 |               |             | resources.                         |
 |               +-------------+------------------------------------+
 |               | Operational | Cloud administrator requests       |
 |               | Task Intent | execution of any automated task    |
 |               |             | other than cloud management        |
 |               |             | intents and cloud resource         |
 |               |             | management intents.                |
 |               |             |                                    |
 |               |             | Example: Request upgrade operating |
 |               |             | system to version X on all VMs in  |
 |               |             | network N1.                        |
 |               |             |                                    |
 |               |             | Operational statement: An intent   |
 |               |             | to update a system might           |
 |               |             | reconfigure the system topology    |
 |               |             | (connect to a service and to       |
 |               |             | peers), exchange data (update the  |
 |               |             | content), and uphold a certain QoE |
 |               |             | level (allocate sufficient network |
 |               |             | resources).  Thus, the network     |
 |               |             | carries out the necessary          |
 |               |             | configuration to best serve such   |
 |               |             | an intent, e.g., setting up direct |
 |               |             | connections between terminals and  |
 |               |             | allocating fair shares of router   |
 |               |             | queues considering other network   |
 |               |             | services.                          |
 |               +-------------+------------------------------------+
 |               | Strategy    | Cloud administrator designs        |
 |               | Intent      | models, policy intents, and        |
 |               |             | workflows to be used by other      |
 |               |             | intents.  Automate any tasks that  |
 |               |             | administrator often performs in    |
 |               |             | addition to life cycle of cloud    |
 |               |             | management intents and cloud       |
 |               |             | management resource intents.       |
 |               |             |                                    |
 |               |             | Example: In case of emergency,     |
 |               |             | automatically migrate all cloud    |
 |               |             | resources to DC2.                  |
 +---------------+-------------+------------------------------------+
 | Underlay      | Underlay    | Service created and provided by    |
 | Network       | Network     | the underlay network               |
 | Administrator | Service     | administrator.                     |
 |               | Intent      |                                    |
 |               |             | Example: Request underlay service  |
 |               |             | between DC1 and DC2 with bandwidth |
 |               |             | B.                                 |
 |               +-------------+------------------------------------+
 |               | Underlay    | Underlay network administrator     |
 |               | Network     | requests some DCN-wide underlay    |
 |               | Intent      | network configuration or network   |
 |               |             | resource configurations.           |
 |               |             |                                    |
 |               |             | Example: Establish and allocate    |
 |               |             | DHCP address pool.                 |
 |               +-------------+------------------------------------+
 |               | Operational | Underlay network administrator     |
 |               | Task Intent | requests execution of any          |
 |               |             | automated task other than underlay |
 |               |             | network service and resource       |
 |               |             | intent.                            |
 |               |             |                                    |
 |               |             | Example: Request automatic rapid   |
 |               |             | detection of device failures and   |
 |               |             | pre-alarm correlation.             |
 |               +-------------+------------------------------------+
 |               | Strategy    | Underlay network administrator     |
 |               | Intent      | designs models, policy intents,    |
 |               |             | and workflows to be used by other  |
 |               |             | intents.  Automate any tasks that  |
 |               |             | the administrator often performs.  |
 |               |             |                                    |
 |               |             | Example: For all traffic flows     |
 |               |             | that need NFV service chaining,    |
 |               |             | restrict the maximum load of any   |
 |               |             | VNF node/container below 50% and   |
 |               |             | the maximum load of any network    |
 |               |             | link below 70%.                    |
 +---------------+-------------+------------------------------------+
 | Application   | Cloud       | Cloud management intent API        |
 | Developer     | Management  | provided to the application        |
 |               | Intent      | developers.                        |
 |               |             |                                    |
 |               |             | Example: API to request            |
 |               |             | configuration of VMs or DB         |
 |               |             | Servers.                           |
 |               +-------------+------------------------------------+
 |               | Cloud       | Cloud resource management intent   |
 |               | Resource    | API provided to the application    |
 |               | Management  | developers.                        |
 |               | Intent      |                                    |
 |               |             | Example: API to request automatic  |
 |               |             | life-cycle management of cloud     |
 |               |             | resources.                         |
 |               +-------------+------------------------------------+
 |               | Underlay    | Underlay network service API       |
 |               | Network     | provided to the application        |
 |               | Service     | developers.                        |
 |               | Intent      |                                    |
 |               |             | Example: API to request real-time  |
 |               |             | monitoring of device condition.    |
 |               +-------------+------------------------------------+
 |               | Underlay    | Underlay network resource API      |
 |               | Network     | provided to the application        |
 |               | Intent      | developers.                        |
 |               |             |                                    |
 |               |             | Example: API to request dynamic    |
 |               |             | management of IPv4 address pool    |
 |               |             | resources.                         |
 |               +-------------+------------------------------------+
 |               | Operational | Operational task intent API        |
 |               | Task Intent | provided to the trusted            |
 |               |             | application developer (internal    |
 |               |             | DevOps).                           |
 |               |             |                                    |
 |               |             | Example: API to request automatic  |
 |               |             | rapid detection of device failures |
 |               |             | and pre-alarm correlation.         |
 |               +-------------+------------------------------------+
 |               | Strategy    | Application developer designs      |
 |               | Intent      | models, policy intents, and        |
 |               |             | building blocks to be used by      |
 |               |             | other intents.  This is for the    |
 |               |             | trusted internal DCN DevOps.       |
 |               |             |                                    |
 |               |             | Example: API to request load-      |
 |               |             | balancing thresholds.              |
 +---------------+-------------+------------------------------------+
   Table 3: Intent Classification for Data Center Network Solutions

6.4.2. Intent Categories

 The following are the proposed categories:
 Intent Scope:  C1=Connectivity, C2=Security/Privacy, C3=Application,
    C4=QoS, C5=Storage, C6=Compute
 Network Scope
    Network Domain:  DC Network
    DCN Network (DCN Net) Scope:  C1=Logical, C2=Physical
    DCN Resource (DCN Res) Scope:  C1=Virtual, C2=Physical
 Abstraction (ABS):  C1=Technical (with technical feedback), C2=Non-
    technical (without technical feedback) (see Section 5.2).
 Life cycle (L-C):  C1=Persistent (full life cycle), C2=Transient
    (short lived)

6.4.3. Intent Classification Example

 This section depicts an example on how the methodology described in
 Section 6.1 can be used by the research community to classify
 intents.  As mentioned in Section 6.3.3, a successful use of the
 classification proposed in this document is introduced in the PoC
 demonstration titled "A Multi-Level Approach to IBN" [POC-IBN].  The
 PoC is led by academics carrying out research in the area of SDN/NFV;
 the specific problem they are addressing is the application of the
 intent concept at different levels that correspond to different
 stakeholders.
 For their research work, they considered two types of intents: slice
 intents and service chain intents.  For the data center solution,
 only the slice intent is relevant.
 As already mentioned in Section 6.3.3, a slice intent expresses a
 request for a network slice with two types of components: a set of
 top-layer virtual functions and a set of virtual switches and/or
 routers of L2/L3 VNFs.
 Following the intent classification methodology described step by
 step in Section 6.1, we identify the following:
 1.  The intent solution is data center.
 2.  The intent user type is the cloud administrator for the slice
     intent and service chain intent.
 3.  The type of intent is a cloud management intent for the slice
     intent.
 4.  The intent scopes are connectivity and application.
 5.  The network scope is logical; the resource scope is virtual.
 6.  The abstractions are with technical feedback for the slice
     intent.
 7.  The life cycle is persistent.
 The following table shows how to represent this information in a
 tabular form; the "X" in the table refers to the slice intent.
 +===========+=============+=================+=====+=====+=====+=====+
 |Intent User| Intent Type |Intent           |DCN  |DCN  |ABS  |L-C  |
 |           |             |Scope            |Res  |Net  |     |     |
 |           |             +==+==+==+==+==+==+==+==+==+==+==+==+==+==+
 |           |             |C1|C2|C3|C4|C5|C6|C1|C2|C1|C2|C1|C2|C1|C2|
 +===========+=============+==+==+==+==+==+==+==+==+==+==+==+==+==+==+
 |Customer/  | Customer    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |Tenants    | Service     |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Strategy    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 +-----------+-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |Cloud Admin| Cloud       |X |  |X |  |  |  |X |  |X |  |X |  |X |  |
 |           | Management  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Cloud       |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Resource    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Management  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Operational |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Task Intent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Strategy    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 +-----------+-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |Underlay   | Underlay    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |Network    | Network     |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |Admin      | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Underlay    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Network     |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Resource    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Operational |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Task Intent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Strategy    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 +-----------+-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |App        | Cloud       |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |Developer  | Management  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Cloud       |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Resource    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Management  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Underlay    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Network     |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Underlay    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Network     |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Resource    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Operational |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Task Intent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           +-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 |           | Strategy    |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 |           | Intent      |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
 +-----------+-------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    Figure 4: Intent Classification Example for Data Center Network
                               Solutions

6.5. Intent Classification for Enterprise Solution

6.5.1. Intent Users and Intent Types

 The following table describes the intent users in enterprise
 solutions and their intent types.
 +---------------+-------------+------------------------------------+
 | Intent User   | Intent Type | Intent Type Description            |
 +---------------+-------------+------------------------------------+
 | End User      | Customer    | Enterprise end user self service   |
 |               | Service     | or applications; enterprise may    |
 |               | Intent      | have multiple types of end users.  |
 |               |             |                                    |
 |               |             | Example: Request access to VPN     |
 |               |             | service.  Request video conference |
 |               |             | between end user A and B.          |
 |               +-------------+------------------------------------+
 |               | Strategy    | This includes models and policy    |
 |               | Intent      | intents designed by end users to   |
 |               |             | be used by end-user intents and    |
 |               |             | their applications.                |
 |               |             |                                    |
 |               |             | Example: Create a video conference |
 |               |             | type for a weekly meeting.         |
 +---------------+-------------+------------------------------------+
 | Enterprise    | Network     | Service provided by the            |
 | Administrator | Service     | administrator to the end users and |
 | (internal or  | Intent      | their applications.                |
 | MSP)          |             |                                    |
 |               |             | Example: For any end user of       |
 |               |             | application X, the arrival of      |
 |               |             | hologram objects of all the remote |
 |               |             | tele-presenters should be          |
 |               |             | synchronized within 50 ms to reach |
 |               |             | the destination viewer for each    |
 |               |             | conversation session.  Create      |
 |               |             | management VPN connectivity for    |
 |               |             | type of service A.                 |
 |               |             |                                    |
 |               |             | Operational statement: The job of  |
 |               |             | the network layer is to ensure     |
 |               |             | that the delay is between 50-70 ms |
 |               |             | through the routing algorithm.  At |
 |               |             | the same time, the node resources  |
 |               |             | need to meet the bandwidth         |
 |               |             | requirements of 4K video           |
 |               |             | conferences.                       |
 |               +-------------+------------------------------------+
 |               | Network     | Administrator requires network-    |
 |               | Intent      | wide configuration (e.g., underlay |
 |               |             | or campus) or resource             |
 |               |             | configuration (switches, routers,  |
 |               |             | or policies).                      |
 |               |             |                                    |
 |               |             | Example: Configure switches in     |
 |               |             | campus network 1 to prioritize     |
 |               |             | traffic of type A.  Configure      |
 |               |             | YouTube as business non-relevant.  |
 |               +-------------+------------------------------------+
 |               | Operational | Administrator requests execution   |
 |               | Task Intent | of any automated task other than   |
 |               |             | network service intents and        |
 |               |             | network intents.                   |
 |               |             |                                    |
 |               |             | Example: Request network security  |
 |               |             | automated tasks such as web        |
 |               |             | filtering and DDoS cloud           |
 |               |             | protection.                        |
 |               +-------------+------------------------------------+
 |               | Strategy    | Administrator designs models,      |
 |               | Intent      | policy intents, and workflows to   |
 |               |             | be used by other intents.          |
 |               |             | Automate any tasks that the        |
 |               |             | administrator often performs.      |
 |               |             |                                    |
 |               |             | Example: In case of emergency,     |
 |               |             | automatically shift all traffic of |
 |               |             | type A through network N.          |
 +---------------+-------------+------------------------------------+
 | Application   | End-User    | End-user service / application     |
 | Developer     | Intent      | intent API provided to the         |
 |               |             | application developers.            |
 |               |             |                                    |
 |               |             | Example: API for request to open a |
 |               |             | VPN service.                       |
 |               +-------------+------------------------------------+
 |               | Network     | Network service API provided to    |
 |               | Service     | application developers.            |
 |               | Intent      |                                    |
 |               |             | Example: API for request network   |
 |               |             | bandwidth and latency for hosting  |
 |               |             | a video conference.                |
 |               +-------------+------------------------------------+
 |               | Network     | Network API provided to            |
 |               | Intent      | application developers.            |
 |               |             |                                    |
 |               |             | Example: API for requesting        |
 |               |             | network device configuration.      |
 |               +-------------+------------------------------------+
 |               | Operational | Operational task intent API        |
 |               | Task Intent | provided to the trusted            |
 |               |             | application developer (internal    |
 |               |             | DevOps).                           |
 |               |             |                                    |
 |               |             | Example: API for requesting        |
 |               |             | automatic monitoring and           |
 |               |             | interception for network security. |
 |               +-------------+------------------------------------+
 |               | Strategy    | Application developer designs      |
 |               | Intent      | models, policy intents, and        |
 |               |             | building blocks to be used by      |
 |               |             | other intents.  This is for the    |
 |               |             | trusted internal DevOps.           |
 |               |             |                                    |
 |               |             | Example: API for strategy intent   |
 |               |             | in case of emergencies.            |
 +---------------+-------------+------------------------------------+
        Table 4: Intent Classification for Enterprise Solution

6.5.2. Intent Categories

 The following are the proposed categories:
 Intent Scope:  C1=Connectivity, C2=Security/Privacy, C3=Application,
    C4=QoS
 Network (Net) Scope:  C1=Campus, C2=Branch, C3=SD-WAN
 Abstraction (ABS):  C1=Technical (with technical feedback), C2=Non-
    technical (without technical feedback) (see Section 5.2)
 Life cycle (L-C):  C1=Persistent (full life cycle), C2=Transient
    (short lived)
 The following is the intent classification table example for
 enterprise solutions.
 +---------------+-------------+-----------+--------+-----+-----+
 | Intent User   | Intent Type | Intent    | Net    | ABS | L-C |
 |               |             | Scope     |        |     |     |
 |               |             +-----------+--------+-----+-----+
 |               |             |C1|C2|C3|C4|C1|C2|C3|C1|C2|C1|C2|
 +---------------+-------------+--+--+--+--+--+--+--+--+--+--+--+
 | End User      | Customer    |  |  |  |  |  |  |  |  |  |  |  |
 |               | Service     |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 |               +-------------+--+--+--+--+--+--+--+--+--+--+--+
 |               | Strategy    |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 +---------------+-------------+--+--+--+--+--+--+--+--+--+--+--+
 | Enterprise    | Network     |  |  |  |  |  |  |  |  |  |  |  |
 | Administrator | Service     |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 |               +-------------+--+--+--+--+--+--+--+--+--+--+--+
 |               | Network     |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 |               +-------------+--+--+--+--+--+--+--+--+--+--+--+
 |               | Operational |  |  |  |  |  |  |  |  |  |  |  |
 |               | Task        |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 |               +-------------+--+--+--+--+--+--+--+--+--+--+--+
 |               | Strategy    |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 +---------------+-------------+--+--+--+--+--+--+--+--+--+--+--+
 | Application   | End-User    |  |  |  |  |  |  |  |  |  |  |  |
 | Developer     | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 |               +-------------+--+--+--+--+--+--+--+--+--+--+--+
 |               | Network     |  |  |  |  |  |  |  |  |  |  |  |
 |               | Service     |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 |               +-------------+--+--+--+--+--+--+--+--+--+--+--+
 |               | Network     |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 |               +-------------+--+--+--+--+--+--+--+--+--+--+--+
 |               | Operational |  |  |  |  |  |  |  |  |  |  |  |
 |               | Task        |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 |               +-------------+--+--+--+--+--+--+--+--+--+--+--+
 |               | Strategy    |  |  |  |  |  |  |  |  |  |  |  |
 |               | Intent      |  |  |  |  |  |  |  |  |  |  |  |
 +---------------+-------------+--+--+--+--+--+--+--+--+--+--+--+
          Figure 5: Intent Categories for Enterprise Solution

7. Conclusions

 This document is aligned with the RG objectives and supports
 investigations into intent-based networking by proposing an intent
 categorization methodology and taxonomy.  It brings clarification to
 what an intent represents for different stakeholders through the
 proposal of an intent classification approach, ensuring that a common
 understanding among all the participants exists.  This, together with
 the proposed intent taxonomy provides a solid foundation for future
 intent-related discussions within the NMRG.
 The benefits of this intent classification document in the research
 community have been demonstrated through a PoC implementation
 [POC-IBN] in which the document's concepts have been applied at
 different levels corresponding to different stakeholders.

8. Security Considerations

 This document identifies security and privacy as categories of the
 intent scope.  The intents could be solely security intents and
 privacy intents, or security can be embedded in the intents that
 include also connectivity, application, and QoS scope.
 Security and privacy scope is when the intent specifies the security
 characteristics of the network, customers, or end users, and privacy
 for customers and end users.
 More details of these security intents will be described in future
 documents that specify architecture, functionality, user intents, and
 models.  An analysis of the security considerations of the overall
 intent-based system is provided in Section 9 of [RFC9315].

9. IANA Considerations

 This document has no IANA actions.

10. Informative References

 [Banerjee21]
            Banerjee, A., Mwanje, S., and G. Carle, "Contradiction
            Management in Intent-driven Cognitive Autonomous RAN",
            September 2021.
 [Bezahaf19]
            Bezahaf, M., Hernandez, M., Bardwell, L., Davies, E.,
            Broadbent, M., King, D., and D. Hutchison, "Self-Generated
            Intent-Based System", 10th International Conference on
            Networks of the Future (NoF),
            DOI 10.1109/NoF47743.2019.9015045, October 2019,
            <https://doi.org/10.1109/NoF47743.2019.9015045>.
 [Bezahaf21]
            Bezahaf, M., Davies, E., Rotsos, C., and N. Race, "To All
            Intents and Purposes: Towards Flexible Intent Expression",
            IEEE 7th International Conference on Network
            Softwarization (NetSoft),
            DOI 10.1109/NetSoft51509.2021.9492554, July 2021,
            <https://doi.org/10.1109/NetSoft51509.2021.9492554>.
 [Davoli21] Davoli, G., "Programmability and Management of Software-
            Defined Network Infrastructures", 2021.
 [IFIP-NSM] IFIP, "Network and Service Management Taxonomy",
            <https://www.simpleweb.org/ifip/taxonomy.html>.
 [Jacobs18] Jacobs, A., Pfitscher, R., Ferreira, R., and L. Granville,
            "Refining Network Intents for Self-Driving Networks",
            Proceedings of the Afternoon Workshop on Self-Driving
            Networks (SelfDN), DOI 10.1145/3229584.3229590, August
            2018, <https://doi.org/10.1145/3229584.3229590>.
 [Leivadeas21]
            Leivadeas, A. and M. Falkner, "VNF Placement Problem: A
            Multi-Tenant Intent-Based Networking Approach", 24th
            Conference on Innovation in Clouds, Internet and Networks
            and Workshops (ICIN), DOI 10.1109/ICIN51074.2021.9385553,
            March 2021,
            <https://doi.org/10.1109/ICIN51074.2021.9385553>.
 [Mehmood21]
            Mehmood, K., Kralevska, K., and D. Palma, "Intent-driven
            Autonomous Network and Service Management in Future
            Networks: A Structured Literature Review",
            DOI 10.48550/arXiv.2108.04560, August 2021,
            <https://doi.org/10.48550/arXiv.2108.04560>.
 [ONF]      Open Networking Foundation, "Intent NBI - Definition and
            Principles", October 2016,
            <https://opennetworking.wpengine.com/wp-
            content/uploads/2014/10/TR-
            523_Intent_Definition_Principles.pdf>.
 [ONOS]     Koshibe, A., "Intent Framework", 2016,
            <https://wiki.onosproject.org/display/ONOS/
            Intent+Framework/>.
 [Padovan20]
            Padovan, S., "Design and Implementation of a Blockchain
            Intent Management System", November 2020.
 [POC-IBN]  Martini, B., Cerroni, W., Gharbaoui, M., and D. Borsatti,
            "A Multi-Level Approach to IBN", IETF 108 Hackathon
            Report, July 2020,
            <https://www.ietf.org/proceedings/108/slides/slides-108-
            nmrg-ietf-108-hackathon-report-a-multi-level-approach-to-
            ibn-02>.
 [RFC9315]  Clemm, A., Ciavaglia, L., Granville, L. Z., and J.
            Tantsura, "Intent-Based Networking - Concepts and
            Definitions", RFC 9315, DOI 10.17487/RFC9315, October
            2022, <https://www.rfc-editor.org/info/rfc9315>.
 [Szilagyi21]
            Szilágyi, P., "I2BN: Intelligent Intent Based Networks",
            Journal of ICT Standardization, Volume 9, Issue 2,
            DOI 10.13052/jicts2245-800X.926, June 2021,
            <https://doi.org/10.13052/jicts2245-800X.926>.
 [Tian19]   Tian, B., Zhang, X., Zhai, E., Liu, H., Ye, Q., Wang, C.,
            Wu, X., Ji, Z., Sang, Y., Zhang, M., Yu, D., Tian, C.,
            Zheng, H., and B. Zhao, "Safely and automatically updating
            in-network ACL configurations with intent language",
            SIGCOMM '19: Proceedings of the ACM Special Interest Group
            on Data Communication, DOI 10.1145/3341302.3342088, August
            2019, <https://doi.org/10.1145/3341302.3342088>.
 [TMF-AUTO] Boasman-Patel, A., Sun, D., Wang, Y., Maitre, C.,
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Acknowledgments

 This document has benefited from reviews, suggestions, comments, and
 proposed text provided by the following members listed in
 alphabetical order: Mehdi Bezahaf, Brian E. Carpenter, Laurent
 Ciavaglia, Benoit Claise, Alexander Clemm, Yehia Elkhatib, Jerome
 Francois, Pedro Andres Aranda Gutierrez, Daniel King, Branislav
 Meandzija, Bob Natale, Juergen Schoenwaelder, Xiaolin Song, and Jeff
 Tantsura.
 We thank Barbara Martini, Walter Cerroni, Molka Gharbaoui, and Davide
 Borsatti for contributing with their "A multi-level approach to IBN"
 PoC demonstration, a first attempt to adopt the intent classification
 methodology.

Contributors

 The following people all contributed to creating this document:
 Contributed significant text:
 Xueyuan Sun
 China Telecom
 Will (Shucheng) Liu
 Huawei
 Contributed text in early draft versions of this document:
 Ying Chen
 China Unicom
 John Strassner
 Huawei
 Weiping Xu
 Huawei
 Richard Meade
 Huawei

Authors' Addresses

 Chen Li
 China Telecom
 Xicheng District
 No.118 Xizhimennei street
 Beijing
 100035
 China
 Email: lichen6@chinatelecom.cn
 Olga Havel
 Huawei Technologies
 Ireland
 Email: olga.havel@huawei.com
 Adriana Olariu
 Huawei Technologies
 Ireland
 Email: adriana.olariu@huawei.com
 Pedro Martinez-Julia
 NICT
 Japan
 Email: pedro@nict.go.jp
 Jeferson Campos Nobre
 Federal University of Rio Grande do Sul (UFRGS)
 Porto Alegre-RS
 Brazil
 Email: jcnobre@inf.ufrgs.br
 Diego R. Lopez
 Telefonica I+D
 Don Ramon de la Cruz, 82
 28006 Madrid
 Spain
 Email: diego.r.lopez@telefonica.com
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