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INTERNET-DRAFT                                               Y. Xia, Ed.
Intended Status: Standards Track                            T. Zhou, Ed.
Expires: November 23, 2015                                 Y. Zhang, Ed.
                                                                S. Hares
                                                                  Huawei
                                                               P. Aranda
                                                                D. Lopez
                                                             Telefornica
                                                            J. Crowcroft
                                                    Cambridge University
                                                                Y. Zhang
                                                            China Unicom
                                                            May 22, 2015


                    Intent Common Information Model
                        draft-xia-ibnemo-icim-00


Abstract

   Intent Common Information Model (ICIM) generalizes a unified model
   for expressing different layers' intent whatever role,
   responsibility, knowledge, etc. This document provides an information
   model to be inherited and expanded to construct specific intent model
   in different areas. According to this information model, network
   intent model is put forward which can satisfy users' need in
   different layers, such as, end-users, business developers, and
   network administers.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
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   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html




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Copyright and License Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors. All rights reserved.

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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.



Table of Contents

   1  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  4
   2. Intent Common Information Model Overview  . . . . . . . . . . .  4
     2.1  Elements  . . . . . . . . . . . . . . . . . . . . . . . . .  5
       2.1.1  User  . . . . . . . . . . . . . . . . . . . . . . . . .  5
       2.1.2  Context . . . . . . . . . . . . . . . . . . . . . . . .  5
       2.1.3  Object  . . . . . . . . . . . . . . . . . . . . . . . .  5
       2.1.4  Result  . . . . . . . . . . . . . . . . . . . . . . . .  5
       2.1.5  Operation . . . . . . . . . . . . . . . . . . . . . . .  6
     2.2  Relationships in ICIM . . . . . . . . . . . . . . . . . . .  6
       2.2.1  Relationship between Result and Operation . . . . . . .  6
       2.2.2  Relationship between Object and Operation . . . . . . .  7
       2.2.3  Relationship between Object and Result  . . . . . . . .  7
     2.3  Intent and Policy . . . . . . . . . . . . . . . . . . . . .  7
     2.4  Layers of Intent  . . . . . . . . . . . . . . . . . . . . .  8
   3.  Intent Modeling  . . . . . . . . . . . . . . . . . . . . . . .  8
     3.1  Intent overview . . . . . . . . . . . . . . . . . . . . . .  8
     3.2  Top level intent expression . . . . . . . . . . . . . . . .  8
     3.3  Objects in the network  . . . . . . . . . . . . . . . . . .  9
     3.4  Type of result  . . . . . . . . . . . . . . . . . . . . . . 10
     3.5  Operation composition . . . . . . . . . . . . . . . . . . . 10
   4  Security Considerations . . . . . . . . . . . . . . . . . . . . 12
   5  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 12
   6  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 12
   7  Informative References  . . . . . . . . . . . . . . . . . . . . 12



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   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12


















































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1  Introduction

   Intent is a new philosophy to design open interface. Opposite to the
   'bottom up' method which opens what system has, Intent interface uses
   'top down' method which opens what user's requirement. With this
   Intent interface, users just need to express what their requirements
   are, rather than how to implement them, so Intent interface is user
   friendly. Intent interface is much closer to user, but different
   users have different intention manifestations, which have different
   granularity or different level. It depends on users' role, knowledge
   and their purpose. Intent can be some final results of objects and
   also can be some specific operations on objects in specific context.
   Although dictating operations is the manifestation of intent, a user
   just need to assign the operations he cares about, and has no need to
   plan complete and detailed operations list for the system to achieve
   the intent.

   Intent Common Information Model (ICIM) generalizes a generic model
   for expressing key components of intent interface and the
   relationship between these components. This document provides a
   common model to be inherited and expanded to construct specific
   intent interface in specific areas. According to this information
   model, intent interface in network area is put forward which can
   satisfy user' intention in different layers or different roles, such
   as, end-users, business developers, network administers, etc

1.1  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2. Intent Common Information Model Overview

   Intent Common Information Model aims to generalize a unified
   information model which satisfied different areas, scenarios, and
   other constraints. So, it is a complete and detailed information
   model to define the constituent elements of intent, but some elements
   can be omitted or implied under some special situations when using
   this model to express specific data model.

   From the overall perspective, construction elements of intent can be
   generalized into user of intent who author and own this intent,
   intent content which is a desired purpose and the specific context
   for implementing intent. Furthermore, in general, person's intent
   content is often visioning ultimate state of some objects or
   performing actions to these objects, so intent content can be
   abstracted into object which is the target for intent, result which



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   is a desired state and operation which is the specific actions to
   achieve a purpose.

2.1  Elements

2.1.1  User

   User is an abstract class which refers the subject and owner to
   express the intent. For example, end-users, business designers,
   network administrators are all instances of User class. Intent has a
   strong relationship with the user. So intent is different for
   specific user when this information model is applied to specific
   scenario. So when ICIM is implemented, this class will involve a role
   mapping.

2.1.2  Context

   Context refers to a set of specific background information such as,
   timer, price, and so on. Context has a huge influence on a person
   designing a detailed  plan or selecting the best program to achieve a
   purpose. For example, when an enterprise plans to build a dedicated
   connection between two sites, price and distance will be the context
   in this scenario. While may not be part of how an entity expresses or
   executes some intent, it is a factor that must be considered with the
   expression of intent.

2.1.3  Object

   Object refers an abstract class which defines some entities affected
   or managed by intent. For the management, users could manage life
   cycle of the objects through some concrete operations, such as,
   create, update, delete, etc. In addition, users could use other
   specific operations to affect the behavior of managed objects. For
   example, a business designer want all traffic be filtered by a
   special firewall. The object of this business designers intent could
   be the all traffic flowing on a specific network (e.g. L3VPN), and
   this intent impacts the forwarding behavior of the traffic network.
   Object is different in specific area. In network area, object is an
   aggregation class with node, connection and flow. For objects, users
   could construct some specific objects to achieve intent, and it is
   also allowed for users to assign intent to existing resources.

2.1.4  Result

   Result is a type of intent which refers to an ultimate state or
   something an individual wants to achieve. This type of intent shields
   difference and diversity of an environment away from the users'
   intent. The person just envisions the ultimate state of objects



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   without worrying about how to achieve it. For example, a result could
   be that the company accesses any sites on the Internet safely.  It
   just defines a result that ignores technology details, such as,
   firewall, ACL, and so on.

   Though desired state is a general requirement, violation state is
   another special state which has an important status when achieving
   integral compliance. For example, a typical scenario is all virtual
   machines owned by different tenants should not be deployed in a same
   hypervisor. This type of result just shows the undesired state which
   is a type of violation state, and this kind of intent should be
   involved in this information model.

2.1.5  Operation

   Operation is a type of intent which refers to some specific actions
   an individual desires to take for realizing the purpose. This type of
   intent formulates explicit plan to realize a purpose which may take a
   better control of the whole system. According to the diversity of
   system support capability, there are large sets of operations for
   users to take.

   Generally, operations can be divided into two categories. One is
   action without condition which is called "command" usually. For
   example, create a virtual machine. This kind of operation defines a
   concrete action which is executed immediately without any trigger.
   The other is action with condition. For this kind of operations,
   condition is a trigger for the action. And actions will not be
   executed immediately until the condition clause is tested to be true.
   For example, "do load balancing when the utilization of a link
   exceeds 80%". In this example, "utilization of a link" is the
   trigger, and "do load balancing" is the action. Action will not be
   taken until the trigger is true.  Actions are different by stages
   which depend on the layer of intent. Actions expressed in upper layer
   may lead to cascaded actions in other lower layers. For example, the
   action "do load balancing" will bring out many actions which are
   depend on technologies and devices.

2.2  Relationships in ICIM

2.2.1  Relationship between Result and Operation

   Users are free to express their intent, no matter it is an ultimate
   result or specific operations in their mind, but there are some
   relationships between these two basic types of intent. For result,
   users just need to express the goal without worrying how to implement
   it in a specific system which facilitates users to focus on real
   requirement. When achieving the ultimate result, it needs some



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   reasoning mechanisms to transfer it to real executable operations
   which are supported by specific system. So in a specific scenario, a
   result can generate concrete operations. For example, for a
   geographical distributed enterprise, its intent is constructing a
   dedicated line between headquarters and branches at the least cost.
   This intent just expresses a result without defining how to construct
   this dedicated line. So business designers will design the best
   solution and concrete operations referring capability of devices,
   optional programs, prices, etc.

2.2.2  Relationship between Object and Operation

   Operation refers to some specific actions on some objects, so object
   is the target of an action. In general, any action will include some
   objects to execute this action. When users want to execute some
   actions to achieve goals, they may construct the target objects and
   assign specific actions on them, and it is allowed for users to use
   existing resources to do some operations. Though object is the target
   of action, it offers the constraint for optional operations. For
   example, for a virtual machine, the optional operations are create,
   delete, immigrant, etc.

2.2.3  Relationship between Object and Result

   Result refers to some ultimate state for some objects. This type of
   intent does not define which specific operations to take but express
   the desired state of objects. So it is independent on objects'
   capability. For example, intent is all virtual machines' CPU
   utilization could not exceed 80%. It does not assign specific
   operations. So reasoning mechanism will choose suitable operations to
   satisfy this intent, such as, immigrant virtual machine or expand it.

2.3  Intent and Policy

   In industry, Policy already has a clear definition, such as in
   RFC3060. Policy rule consists of an event, a set of conditions and a
   set of actions.  When an event occurs, actions will be taken until
   condition clauses are evaluated to be true.

   As mentioned above, intent refers to a purpose in achieving ultimate
   result or performing operation. The intent has a larger scope
   compared with the policy since Intent can express both result and
   operation.  On one hand if a result is described by intent, there may
   be no specific action given to show how to achieve this intent. On
   the other hand, if operation described by intent, conditions of
   action is optional. Policy is a specific form of operation in
   intent.




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2.4  Layers of Intent

   Intent reflects a person's mental desire which depends on person's
   role, knowledge, and other contextual factors. So users in different
   layers may have different intent. While different layer of intent has
   some differences in content and implementation, the expression of
   each layer of intent is same which defines an ultimate goal or
   dictates specific operations.

   For example, in the network area the intent of end-users could be
   safe connectivity between two sites which a technology independent
   and device independent requirement. For business-based network
   designers, the network connectivity can be selected which is device-
   independent but technology specific. An example of the business-based
   technology is the L3VPN. For network administrators, intent can be
   specific operations on a set of devices such as configuring IP
   addresses on network servers in a data center.

3.  Intent Modeling


   This section defines the concept and hierarchy of intent, and
   describes the Intent Common Information Model.

3.1  Intent overview

   In general, intent is one's specific mental activity, so it strongly
   depends on the subject. Different users may have different
   manifestations and intent. In addition, context, omitted usually, is
   an important factor when achieving purpose, which offers necessary
   background information to impact the decision. Figure 1 illustrates
   the overview of the intent. Figure 1 indicates that the user has
   intent in some context. For example, an enterprise wants to block all
   http traffic in work time. In this intent, the user is the
   enterprise, the intent is to block all http traffic in the work
   hours, and the context includes the definition of the "enterprise"
   and the "work hours".

            +------+  has    +--------+  in    +---------+
            | user +-------->+ intent +------->+ context |
            +------+         +--------+        +---------+

                Figure 1 general prescription for intent

3.2  Top level intent expression

   In Cambridge Dictionaries, the definition of "intent" is the fact
   that you want and plan to do something. So, in general, intent refers



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   to an agent's purpose in getting an ultimate result or performing
   some specific operation. In specific areas, these results or
   operations will relate to some objects. Figure 2 describes the
   general expression of intent.

                             +----------+
                             |  intent  |
                             +-C--A--A--+
                               |  |  |
                   +-----------+  |  +------------+
                   |              |               |
               +---+----+     +---+----+    +-----+-----+
               | object |     | result |    | operation |
               +--------+     +--------+    +-----------+

                       Figure 2 intent expression

   One type of intent is to express key operations that a user wants to
   execute. The underlying intent system can generate a complete
   operation list from user's request. The other type of intent is to
   express an ultimate result or state without dictating any operations.

   For example, intent of a user may be a result without defining how to
   realize it, such as, requiring security communication between two
   sites, or dictate some detailed operations in order to achieve a
   purpose, such as, filtering all traffics by firewall between these
   two sites.

3.3  Objects in the network

   Object is an abstraction class which can be inherited and expanded in
   different area. In network area, the object, i.e. the target of
   intent, can be generalized into Node, Connection and Flow, as shown
   in Figure 3.

                                   +------+
                            +------+ node |
                            |      +------+
               +--------+G+-+
               |        |          +------------+
               | object |G+--------+ connection |
               |        |          +------------+
               +--------+G+-+
                            |      +------+
                            +------+ flow |
                                   +------+

                Figure 3 common objects in network area



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   The Node represents the functions a network node may provide in a
   network such as network services, forwarding functions (firewall,
   load balancer, virtual router, and others), or a group of network
   elements. A group of network elements can be a subnet, an autonomous
   system, or a confederation of autonomous systems.

   The Connection describes logical connectivity between node entities.
   This connection is not limited to any physical link, but just
   expresses the communication capacity between nodes.

   The Flow refers to the traffic in network which describes data
   packets have some certain common characters.

3.4  Type of result

   Result refers an ultimate state which is expected or avoided. Figure
   4 describes two types of result. For example, a user may express an
   intent is his computer's CPU utilization must less than 80%. This
   expression is a type of result which describes an expected state. Of
   course, this user can also express this intent as it's an error when
   his computer's CPU utilization exceeds 80%. This expression is
   another type of result which describe a avoid state. Users are free
   to describe either one.

                              +--------+
                              | result |
                              +-G----G-+
                                |    |
                          +-----+    +----+
                          |               |
                      +---+----+      +---+---+
                      | expect |      | avoid |
                      +--------+      +-------+

                     Figure 4 expression of Result

3.5  Operation composition

   Operation refers to some specific actions in order to achieve some
   purposes. An operation must have some actions. However, if condition
   and constraint need to be defined in operations, it depends on
   specific scenario and users' require. Once a condition is involved in
   operation, actions will not be executed immediately until condition
   is true. In additional, constraint restricts action itself or the
   scope of action.






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                              +-----------+
                              | operation |
                              +-A---C---A-+
                                |   |   |
                  +-------------+   |   +--------------+
                  |                 |                  |
                  |                 |                  |
            +-----+-----+       +---+----+      +------+-----+
            | condition |       | action |      | constraint |
            +-----------+       +--------+      +------------+

                   Figure 5 composition of operation







































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4  Security Considerations

   TBD

5  IANA Considerations

   This draft includes no request to IANA.

6  Acknowledgements

   The authors would like to thanks the valuable comments made by Wei
   Cao, Sheng Jiang, Zhigang Ji, Xuewei Wang, Shixing Liu, Yan Zhang.


7  Informative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", BCP 14, RFC 2119, March 1997.


Authors' Addresses


   Yinben Xia
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   P.R. China

   EMail: xiayinben@huawei.com


   Tianran Zhou
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   P.R. China

   EMail: zhoutianran@huawei.com


   Yali Zhang
   Huawei Technologies Co., Ltd
   Q14, Huawei Campus, No.156 Beiqing Road
   Hai-Dian District, Beijing, 100095
   P.R. China

   EMail: zhangyali369@huawei.com



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   Susan Hares
   Huawei Technologies Co., Ltd
   7453 Hickory Hill
   Saline, MI  48176
   USA

   Email: shares@ndzh.com


   Pedro Andres Aranda
   Telefornica I+D,
   Don Ramon de la Cruz, 82 Street
   Madrid, 28006, Spain

   EMail: pedroa.aranda@telefonica.com


   Diego R. Lopez
   Telefornica I+D,
   Don Ramon de la Cruz, 82 Street
   Madrid, 28006, Spain

   EMail: diego.r.lopez@telefonica.com


   Jon Crowcroft
   University of Cambridge Computer Laboratory
   William Gates Building, 15 JJ Thomson Avenue
   Cambridge, CB3 0FD UK

   Email:  jon.crowcroft@cl.cam.ac.uk


   Yan Zhang
   China Unicom P.R. China

   Email: zhangy1036@chinaunicom.cn














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