Policy-based QoS Management

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For years the Internet networking community has been struggling to develop ways to manage networks. Initial attempts brought mechanisms and protocols that focused on managing and configuring individual networking devices i.e. the Simple Network Management Protocol (SNMP). This model worked well in early deployments of IP management systems for local and metropolitan area networks but now, with the evolution of Quality of Service (QoS) models such as the Differentiated Services framework, the complexity and overhead of operating and administrating networks increases enormously. There is also a need to be able to program management systems and network components to adapt to emerging requirements and subsequently be able to dynamically change the behaviour of the whole system to support modified or additional functionality. The emerging Policy-based Network Management paradigm claims to be a solution to these requirements. Policy-based Management can guide the behaviour of a network or distributed system through high-level declarative directives that are dynamically introduced, checked for consistency, refined and evaluated, resulting typically in a series of low level actions.

This section of the Quality of Service Management Information Portal serves as a focal point for research related to Policy-based Network Management.

General Description

The task of managing information technology resources becomes increasingly complex as managers must take heterogeneous systems, different networking technologies, and distributed applications into consideration. As the number of resources to be managed grows, the task of managing these devices and applications depends on numerous system and vendor specific issues. Policy Based Network Management (PBNM) provides a means by which the administration process can be simplified and largely automated.

A policy, the basic building block of a policy-based system, is a set of rules that govern the choices in behaviour of a system. For a network-specific policy these rules define which traffic should be treated differently in the network, and how so. A policy can be represented at different levels, ranging from business goals to device-specific configuration parameters. Policies belonging to the two extreme levels of abstraction are referred to as high and low-level respectively.

Policies are seen as a way to guide the behaviour of a network or distributed system through high-level, declarative directives. The Internet Engineering Task Force (IETF) has been investigating policies as a means for managing IP-based multi-service networks, focusing more on the specification of protocols and the object-oriented information models for representing policies. The declarative high-level aspect of policies is very important, particularly for human managers since it addresses the current problem of managing heterogeneous network devices in a one-by-one fashion, providing improved scalability. The second important benefit of policies is the ability of adapting the management system to changing or newly emerging requirements without having to interrupt its operation or recode part of its hardwired functionality. The aforementioned salient characteristics of policy-based management constitute the basic reasons for being widely adopted by organisations such as the IETF and Distributed Management Task Force (DMTF) as well as by many equipment vendors, e.g. CISCO, as the new promising management solution.

Policy-based management has been considered by two working groups in the IETF. The first one, Resource Allocation Protocol Working Group (WG), has described a framework for policy-based admission control specifying the two main architectural elements:

  • The Policy Enforcement Point (PEP) represents the component that always runs on the policy-aware node and it is the point where the policy decisions are actually enforced.
  • The Policy Decision Point (PDP) is the point where the policy decisions are made.

The second group, Policy Framework WG, defined policy as an aggregation of Policy Rules. Each policy rule comprises a set of conditions and a corresponding set of actions that are intended to be device and vendor-independent in the form of: if condition then action. The four major functional elements described by this group are:

  • A Policy Management Tool, to enable an entity to define, update and optionally monitor the deployment of Policy Rules.
  • A Policy Repository, to store and retrieve Policy Rules.
  • A Policy Consumer, which is a convenient grouping of functions, responsible for acquiring, deploying and optionally translating Policy Rules into a form useable for Policy Targets.
  • A Policy Target, which is an element whose behaviour is dictated by Policy Rules carrying out the action indicated by the Policy Rule.

QoS Management has always been one of the most popular applications of policies since it enables an Internet Service Provider (ISP) to flexibly guide the behaviour of the network with respect to the different service classes offered to its customers based on its business objectives. Although a lot of work has been proposed in the literature in the area of QoS policies, most of them concentrated on defining low-level policies for configuring edge devices for the purposes of realising the Service Level Agreements (SLAs) established with the ISP customers. A more complete approach that addresses issues related to service management and network-wide resource management has been proposed in the context of the EU IST project TEQUILA. This work provided a holistic view to QoS policies, addressing all aspects of QoS management related to areas such as SLS management and Traffic Engineering both at an offline, network-wide manner as well as at an element management level, driving dynamic operations and management functions.


  • B.Alpers, H. Plansky, "Concepts and application of Policy-Based Management," Proceedings of the 4th International Symposium on Integrated Network Management (ISINM), Santa Barbara, California, USA, May 1995.
  • M. Brunner and J. Quittek, "MPLS Management using Policies," Proceedings of the IEEE/IFIP International Symposium on Intergrated Network Management (IM), Seattle, WA, USA, May 2001.
  • N. Corradi, N. Dulay, R. Montanari, C. Stefanelli, "Policy-Driven Management of Agent Systems," Proceedings of IEEE International Workshop on Policies for Distributed Systems and Networks (Policy), Bristol, UK, Springer-Verlag, January 2001.
  • N. Damianou, N. Dulay, E. Lupu, M. Sloman, "The Ponder Policy Specification Language," Proceedings of IEEE International Workshop on Policies for Distributed Systems and Networks (Policy), Bristol, UK, Springer-Verlag, January 2001.
  • M. Fernandez et al., "QoS Provisioning across a DiffServ Domain using Policybased Management," Proceedings of IEEE Globecom 2001, San Antonio, Texas, June 2001.
  • P. Flegkas, P.Trimintzios, G. Pavlou, I. Andrikopoulos, C. F. Cavalcanti, "On Policy based Extensible Hierarchical Network Management in QoS-enabled IP Networks," Proceedings of IEEE International Workshop on Policies for Distributed Systems and Networks (Policy), Bristol, UK, Springer-Verlag, January 2001.
  • P. Flegkas, P. Trimintzios, G. Pavlou, "A Policy-based Quality of Service Management System for IP Differentiated Services Networks," IEEE Network, special issue on Policy Based Networking, Vol. 16, No. 2, pp. 50-56, IEEE, March 2002.
  • P. Flegkas, P. Trimintzios, G. Pavlou, A. Liotta, "Design and Implementation of a Policy-based Resource Management Architecture," Proceedings of IEEE/IFIP Integrated Management Symposium (IM), Colorado Springs, Colorado, USA, March 2003.
  • T. K. Kim, D. Y. Lee, O. H. Byeon and T.M. Chung, "A Policy Propagation Model Using Mobile Agents in Large-Scale Distributed Network Environments," Proceedings of the First International Conference on Service Oriented Computing (ICSOC), Italy, December 2003.
  • T. Koch, B. Krämer, G. Rohde, "On a rule based management architecture, Proceedings of the 2nd International Workshop on Services in Distributed and Networked Environments," IEEE Computer Society Press, pp. 68-75, 1995.
  • L. Lymberopoulos, E. Lupu, M. Sloman, "An Adaptive Policy Based Framework for Network Services Management," Plenum Press Journal of Network and Systems Management, Special Issue on Policy Based Management, Vol 11, No. 3, p277-303, September 2003.
  • L. Lymberopoulos, E. Lupu, M. Sloman, "Ponder Policy Implementation and Validation in a CIM and Differentiated Services Framework," Proceedings of 9th IEEE/IFIP Network Operations and Management Symposium (NOMS), Seoul, Korea, April 2004.
  • D. Marriott, M. Sloman, "Implementation of a Management Agent for Interpreting Obligation Policy," Proceedings of 7th IFIP/IEEE International Workshop on Distributed Systems: Operations & Management (DSOM), L’Aquila, Italy, October 1996.
  • M. Martinez, M. Brunner, J. Quittek, F. Strauß, J. Schönwälder, S. Mertens and T. Klie, "Using the Script MIB for Policy-based Configuration Management," Proceedings of IEEE/IFIP Network Operations and Management Symposium (NOMS), Florence, Italy, April 2002.
  • J. Moffett, M. Sloman, "Policy Hierarchies for Distributed Systems Management," IEEE Journal on Selected Areas in Communications, Vol. 11, No. 9, pp. 1404- 1414, December 1993.
  • Ponnappan, L. Yang, R. Pillai, "A Policy Based QoS Management System for the IntServ/DiffServ Based Internet," Proceedings of 3rd International Workshop on Policies for Distributed Systems and Networks (POLICY), Monterey, California, June 2002.
  • P. Putter, J. Bishop, J. Roos, "Towards Policy Driven Systems Management," Proceedings of 4th International Symposium on Integrated Network Management (ISINM), Santa Barbara, California, USA, May 1995.
  • B. Moore, E. Ellesson, J. Strassner and A. Westerinen, "Policy Core Information Model -- Version 1 Specification," RFC 3060, IETF, February 2001.
  • K. Chan, et al., "Differentiated Services Quality of Service Policy Information Base," RFC 3317, IETF, March 2003.
  • B. Moore et al., "Policy Core Information Model (PCIM) extensions," RFC 3460, IETF, January 2003.
  • H. Schwingel-Horner, G. Bonn, "IDSM Authorisation Policy Specification and Enforcement in a Hierarchical Management Environment," Proceedings of 5th IFIP/IEEE International Workshop on Distributed Systems: Operations & Management (DSOM), Toulouse, France, October 1994.
  • M. Sloman, "Policy Driven Management For Distributed Systems," Journal of Network and Systems Management, Vol. 2, No. 4, pp. 333-360, Plenum Publishing, December 1994.
  • P. Trimintzios, P.Flegkas, G. Pavlou, L. Georgiades, D. Griffin, "Policy-based Network Dimensioning for IP Differentiated Services Networks," Proceedings of IEEE Workshop on IP Operations and Management (IPOM), Dallas, Texas, USA, October 2002.
  • P. Trimintzios, P.Flegkas, G. Pavlou, "Policy-driven Traffic Engineering for Intradomain Quality of Service Provisioning," Proceedings of Quality of Service for future Internet Services (QofIS), Zurich, Switzerland, Springer, October 2002.
  • P. Trimintzios, G. Pavlou, P. Flegkas, P. Georgatsos, A. Asgari, E. Mykoniati, "Service-driven Traffic Engineering for Intra-domain Quality of Service Management," IEEE Network, special issue on Network Management of Multiservice, Multimedia, IP-based Networks, Vol. 17, No. 3, pp. 29-36, IEEE, May 2003.
  • D. Verma, "Policy-Based Networking, Architecture and Algorithms," New Riders Publishing, 2001.

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The list of journals, conferences and technical societies related to Policy-based Network Management does not mean to be exhaustive rather it is indicative. For additions/updates please contact the webmaster.


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