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SUPA                                                               J. Bi
Network Working Group                                Tsinghua University
Internet Draft                                            G. Karagiannis
Intended status: Informational                              J. Strassner
Expires: January 18, 2017                            Huawei Technologies
                                                            D. Romascanu
                                                                   Avaya
                                                                M. Klyus
                                                              NetCracker
                                                                  Q. Sun
                                                           China Telecom
                                                       Luis M. Contreras
                                                              Telefonica
                                                           July 18, 2016




    Problem Statement for Simplified Use of Policy Abstractions (SUPA)
                    draft-bi-supa-problem-statement-02


Abstract

   Simplified Use of Policy Abstractions (SUPA) defines a set of rules
   that define how services are designed, delivered, and operated
   within an operator's environment independent of any one particular
   service or networking device. SUPA expresses policy rules using a
   generic policy information model, which serves as a unifying
   influence to enable different data model implementations to be
   simultaneously developed.


Status of this Memo

   This Internet-Draft is submitted 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
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are working documents of the Internet
   Engineering Task Force (IETF).  Note that other groups may also
   distribute working documents as Internet-Drafts.  The list of
   current Internet-Drafts is at
   http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time.  It is inappropriate to use Internet-Drafts as
   reference material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 18, 2017.


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Copyright Notice

   Copyright (c) 2016 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
   (http://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. Code Components extracted from this
   document must include Simplified BSD License text as described
   in Section 4.e of the Trust Legal Provisions and are provided
   without warranty as described in the Simplified BSD License.


Table of Contents

   1. Introduction...................................................3
      1.1. Problem Statement.........................................3
      1.2. Proposed Solution.........................................4
      1.3. Value of the SUPA Approach ...............................5
   2. Application of Generic Policy-based Management.................6
   3. Terminology....................................................6
   4. Conclusions - Value of SUPA....................................8
   5. Security Considerations........................................8
   6. IANA Considerations............................................8
   7. Contributors...................................................9
   8. Acknowledgments................................................9
   9. References.....................................................9
     9.1 Informative References......................................9
   Authors' Addresses ...............................................9
























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1. Introduction

   The rapid growth in the variety and importance of traffic flowing
   over increasingly complex enterprise and service provider network
   architectures makes the task of network operations and management
   applications and deploying new services much more difficult. In
   addition, network operators want to deploy new services quickly
   and efficiently. Two possible mechanisms for dealing with this
   growing difficulty are the use of software abstractions to
   simplify the design and configuration of monitoring and control
   operations and the use of programmatic control over the
   configuration and operation of such networks. Policy-based
   management can be used to combine these two mechanisms into an
   extensible framework.

   Policy rules can be used to express high-level network operator
   requirements directly, or from a set of management applications,
   to a network management or element system. The network management
   or element system can then control the configuration and/or
   monitoring of network elements and services.

   Simplified Use of Policy Abstractions (SUPA) will define a generic
   policy information model (GPIM) [SUPA-info-model] for use in network
   operations and management applications. The GPIM defines concepts
   and terminology needed by policy management indepednent of the form
   and content of the policy rule. The ECA Policy Rule Information
   Model (EPRIM) [SUPA-info-model] extends the GPIM to define how to
   build policy rules according to the event-condition-action paradigm.

   Both the GPIM and the EPRIM are targeted at controlling the
   configuration and monitoring of network elements throughout the
   service development and deployment lifecycle. The GPIM and the EPRIM
   will both be translated into corresponding YANG [RFC6020] modules
   that define policy concepts, terminology, and rules in a generic and
   interoperable manner; additional YANG modules may also be defined
   from the GPIM and/or EPRIM to manage specific functions.

   The key benefit of policy management is that it enables different
   network elements and services to be instructed to behave the same
   way, even if they are programmed differently. Management
   applications will benefit from using policy rules that enable
   scalable and consistent programmatic control over the
   configuration and monitoring of network elements and services.

1.1. Problem Statement

   Network operators must construct networks of increasing size
   and complexity in order to improve their availability and
   quality, as more and more business services depend on them.

   Currently, different technologies and network elements require
   different forms of the same policy that governs the production of

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   network configuration snippets. The power of policy management is
   its applicability to many different types of systems, services,
   and networking devices. This provides significant improvements in
   configuration agility, error detection, and uptime for operators.

   Many different types of actors can be identified that can use a
   policy management system, including applications, end-users,
   developers, network administrators, and operators. Each of these
   actors typically has different skills and uses different concepts
   and terminologies. For example, an operator may want to express
   that only Platinum and Gold users can use streaming and interactive
   multimedia applications. As a second example, an operator may want
   to define a more concrete policy rule that looks at the number of
   dropped packets. If, for example, this number exceeds a certain
   threshold value, then the applied queuing, dropping and
   scheduling algorithms could be changed in order to reduce the
   number of dropped packets. The power of SUPA is that both of these
   examples may be abstracted. For example, in the latter example,
   different thresholds and algorithms could be defined for different
   classes of service.

1.2. Proposed Solution

   SUPA enables network operators to express policies to control
   network configuration and monitoring data models in a generic
   manner. The configuration and monitoring processes are independent
   of device, as well as domain or type of application, and result in
   configuration according to YANG data models.

   Both of the examples in section 1.1 can be referred to as "policy
   rules", but they take very different forms, since they are defined
   at different levels of abstraction and likely authored by different
   actors. The first example described a very abstract policy rule, and
   did not contain any technology-specific terms, while the second
   example included more concrete policy rules and likely used
   technical terms of a general (e.g., IP address range and port
   numbers) as well as vendor-specific nature (e.g., specific
   algorithms implemented in a particular device). Furthermore,
   these two policy rules could affect each other. For example,
   Gold and Platinum users might need different device
   configurations to give the proper QoS markings to their
   streaming multimedia traffic. This is very difficult to do if a
   common policy framework does not exist.

   Note that SUPA is not limited to any one type of technology.
   While the above two policies could be considered "QoS"
   policies, other examples include:

     - network elements must not accept passwords for logins

     - all SNMP agents in this network must drop all SNMP traffic
       unless it is originating from, or targeting, the
       management network


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     - Periodically perform workload consolidation if average CPU
       utilization falls below X%

   The above three examples are not QoS related; this emphasizes the
   utility of the SUPA approach in being able to provide policies
   to control different types of network element configuration and/or
   monitoring snippets.

   There are many types of policies. SUPA differentiates between
   "management policies" and "embedded policies". Management
   policies are used to control the configuration of network
   elements. Management policies can be interpreted externally to
   network elements, and the interpretation typically results in
   configuration changes of collections of network elements. In
   contrast, "embedded policies" are policies that are embedded
   in the configuration of network elements, and are usually
   interpreted on network elements in isolation. Since embedded
   policies are interpreted in the network device, they are
   typically composed in a very specific fashion to run at
   near-realtime timescales.


1.3. Value of the SUPA Approach

   SUPA will achieve an optimization and reduction in the amount of
   work required to define and implement policy-based data models in
   the IETF. This is due to the generic and extensible framework
   provided by SUPA.

   SUPA defines policy independent of where it is located. Other
   WGs are working on embedding policy in the configuration of a
   network element; SUPA is working on defining policies that
   can be interpreted external to network elements (i.e., management
   policies). Hence, SUPA policies can be used to define the behavior
   of and interaction between embedded policies.

   Since the GPIM defines common policy terminology and concepts, it
   can be used to both define more specific policies as part of a
   data model as well as derive a (more abstract) information model
   from a (more specific) data model.

   This latter approach may be of use in discovering common structures
   that occur in data models that have been designed in isolation of
   each other.

   The SUPA policy framework defines a set of consistent, flexible,
   and scalable mechanisms for monitoring and controlling resources
   and services. It may be used to create a management and operations
   interface that can enable existing IETF data models, such as those
   from I2RS and L3SM, to be managed in a unified way that is
   independent of application domain, technology and vendor. Resource
   and service management become more effective, because policy



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   defines the context that different operations, such as configuration
   and monitoring, are applied to.

2. Terminology

   This section lists the terminology used in this document.

   Action:  a set of purposeful activities that have a set of
      associated behavior.


   Condition:  a set of attributes, features, and/or values that are to
      be compared with a set of known attributes, features, and/or
      values in order to make a decision.  A Condition, when used in
      the context of a Policy Rule, is used to determine whether or not
      the set of Actions in that Policy Rul can be executed or not.


   Data Model:  a data model is a representation of concepts of
      interest to an environment in a form that is dependent on data
      repository, data definition language, query language,
      implementation language, and protocol (typically one or more of
      these).

   ECA:    Event - Condition - Action policy.

   Event:  an Event is defined as any important occurrence in time of
      a change in the system being managed, and/or in the environment
      of the system being managed. An Event, when used in the context
      of a Policy Rule, is used to determine whether the condition
      clause of an imperative Policy Rule can be evaluated or not.

   Information Model:  an information model is a representation of
      concepts of interest to an environment in a form that is
      independent of data repository, data definition language, query
      language, implementation language, and protocol.

   Metadata:  is data that provides descriptive and/or prescriptive
   information about the object(s) to which it is attached.

   Policy Rule:    A Policy Rule is a set of rules that are used to
      manage and control the changing or maintaining of the state of one
      or more managed objects.

3. Application of Generic Policy-based Management

   This section provides examples of how SUPA can be used to define
   different types of policies. Examples applied to various domains,
   including system management, operations management, access control,
   routing, and service function chaining, are also included.
   Note that typical use cases and the applicability of SUPA policy
   models are provided in [SUPA-Applicability].



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   ECA policies are rules that consist of an event clause, a condition
   clause, and an action clause.

      Network Service Management Example

         Event:     too many interface alarms received from an
                    L3VPN service
         Condition: alarms resolve to the same interface within a
                    specified time period
         Action:    if error rate exceeds x% then put L3VPN service
                    to Error State and migrate users to one or more
                    new L3VPNs

      Security Management Example

         Event:     anomalous traffic detected in network
         Condition: determine the severity of the traffic
         Action:    apply one or more actions to affected NEs based
                    on the type of the traffic detected (along with
                    other factors, such as the type of resource
                    being attacked if the traffic is determined to
                    be an attack)

      Traffic Management Examples

         Event:     edge link close to being overloaded by
                    incoming traffic
         Condition: if link utilization exceeds Y% or if link
                    utilization average is increasing over a
                    specified time period
         Action:    change routing configuration to other peers
                    that have better metrics


         Event:     edge link close to be overloaded by
                    outgoing traffic
         Condition: if link utilization exceeds Z% or if link
                    utilization average is increasing over a
                    specified time period
         Action:    reconfigure affected nodes to use source-based
                    routing to balance traffic across multiple links

      Service Management Examples

         Event:     alarm received or periodic time period check
         Condition: CPU utilization level comparison
         Action:    no violation: no action
                    violation:
                      1) determine workload profile in time interval
                      2) determine complementary workloads (e.g.,
                         whose peaks are at different times in day)
                      3) combine workloads (e.g., using integer
                         programming)


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         Event:     alarm received or periodic time check
         Condition: if DSCP == AFxy and
                    throughput < T% or packet loss > P%
         Action:    no: no action
                    yes: remark to AFx'y'; reconfigure queuing;
                    configure shaping to S pps; ...

   Note: it is possible to construct an ECA policy rule that is
   directly tied to configuration parameters.

4. Conclusions: the Value of SUPA

   SUPA can be used to define high-level, possibly network-wide
   policies to create interoperable network element configuration
   snippets. SUPA expresses policies and associated concepts using a
   generic policy information model, and produces generic policy YANG
   data modules. SUPA focuses on management policies that control the
   configuration of network elements. Management policies can be
   interpreted outside of network elements, and the interpretation
   typically results in configuration changes to collections of
   network elements.

   Policies embedded in the configuration of network elements are not
   in the scope of SUPA. In contrast to policies targeted by SUPA,
   embedded policies are usually interpreted on network elements in
   isolation, and often at timescales that require the representation
   of embedded policies to be optimized for a specific purpose.

   The SUPA information model generalizes common concepts from multiple
   technology-specific data models, and makes it reusable.
   Conceptually, SUPA can be used to interface and manage existing and
   future data models produced by other IETF working groups. In
   addition, by defining an object-oriented information model with
   metdata, the characteristics and behavior of data models can be
   better defined.

5. Security Considerations

   Security is a key aspect of any protocol that allows state
   installation and extracting detailed configuration states of network
   elements. This places additional security requirements on SUPA (e.g.,
   authorization, and authentication of network services) that needs
   further investigation. Moreover, policy interpretation can lead to
   corner cases and side effects that should be carefully examined,
   e.g., in case policy rules are conflicting with each other.


6. IANA Considerations

This document has no actions for IANA.





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7. Contributors

   The following people all contributed to creating this document,
   listed in alphabetical order:

      Parviz Yegani, Juniper Networks
      Vikram Choudhary, Huawei Technologies
      Diego Lopez, Telefonica I+D
      J. Schoenwaelder, Jacobs University, Germany
      Will(Shucheng) Liu, Huawei Technologies
      Tina Tsou
      Jean-Francois Tremblay

8. Acknowledgments

   This document has benefited from reviews, suggestions, comments
   and proposed text provided by the following members: H. Rafiee, J.
   Saperia, C. Zhou, Spencer Dawkins, Xing Li, Chongfeng Xie,
   Benoit Claise, Ian Farrer, Marc Blancet, Zhen Cao, Hosnieh Rafiee,
   Mehmet Ersue, Simon Perreault, Fernando Gont, Jose Saldana,
   Tom Taylor, Kostas Pentikousis, Juergen Schoenwaelder, Eric Voit,
   Scott O. Bradner, Marco Liebsch, Scott Cadzow, Marie-Jose Montpetit.

9. References

9.1. Informative References

   [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the
   Network Configuration Protocol (NETCONF)", RFC 6020, October 2010

   [SUPA-info-model] J. Strassner, J. Halpern, "Generic Policy
   Information Model for Simplified Use of Policy Abstractions
   (SUPA)", IETF Internet draft, draft-ietf-supa-generic-policy-
   info-model-00, June 2016

   [SUPA-Applicability] N. Vadrevu, D. Zhang, S. Zhu, Y. Cheng,
   "Applicability of SUPA", IETF Internet draft, draft-vadrevu-supa-
   applicability-06, March 2016

Authors' Addresses

   Georgios Karagiannis
   Huawei Technologies
   Hansaallee 205,
   40549 Dusseldorf,
   Germany
   Email: Georgios.Karagiannis@huawei.com

   Maxim Klyus, Ed.
   NetCracker
   Kozhevnicheskaya str.,7 Bldg. #1
   Moscow, Russia
   E-mail: klyus@netcracker.com


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  Qiong Sun
   China Telecom
   No.118 Xizhimennei street, Xicheng District
   Beijing  100035
   P.R. China
   Email: sunqiong@ctbri.com.cn

   Luis M. Contreras
   Telefonica I+D
   Ronda de la Comunicacion, Sur-3 building, 3rd floor
   Madrid  28050
   Spain
   Email: luismiguel.contrerasmurillo@telefonica.com
   URI:   http://people.tid.es/LuisM.Contreras/

   John Strassner
   Huawei Technologies
   2330 Central Expressway
   Santa Clara, CA 95138 USA
   Email: john.sc.strassner@huawei.com

   Jun Bi
   Tsinghua University
   Network Research Center, Tsinghua University
   Beijing  100084
   China
   EMail: junbi@tsinghua.edu.cn


   Dan Romascanu
   Avaya
   Azrieli Center Holon
   26, HaRokhmim Str., Bldg. D
   Holon, 5885849
   Israel
   Phone: +972-3-645-8414
   Email: dromasca@avaya.com


















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