Policy-based Quality of Service Management in IP Networks

Paris Flegkas

Centre for Communication Systems Research (CCSR), University of Surrey, Guildford, UK.

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 (DiffServ) 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.

The objective of this thesis is to investigate the application of Policy-based Management in the context of QoS Management of IP DiffServ Networks. By using policies as a means for building extensible hierarchical management systems, we propose a novel Policy-based QoS management architecture and specify the relevant policies that can drive its behaviour dynamically, providing a holistic approach to the area of policies for QoS Management.

We first present our view on policies as a means of extending the functionality of management systems dynamically, in conjunction with pre-existing .hard-wired. management logic and provide a generic framework for their application to hierarchical distributed management systems. The programmability aspect of policies is an issue that has not been properly addressed in the literature and constitutes an important contribution of this thesis. We then propose a single architecture for managing an IP DiffServ network, identifying the required functional components and their interactions addressing both service management and resource provisioning (traffic engineering) aspects of QoS Management. The design of the architecture caters for both offline and dynamic operation. Furthermore, we identify the parameters of the functional components of this architecture that are influenced by policies and present an object oriented representation of those policies based on the Policy Core Information Model (PCIM). This work differentiates from relevant work on QoS policies since it addresses the area of QoS Management in its totality, defining policies related to both service management and traffic engineering at a network and element management level.

We finally validate the proposed policy-based framework by presenting a detailed description of the design and implementation of the components of the policy management sub-system needed to be deployed in order to make our system policy-driven and present examples of QoS policies describing their transformation from their definition by the operator until their enforcement.

Key words: Policy-based Management, QoS Management, IP Differentiated Services, Service Management, Traffic Engineering

PhD Thesis, June 2005.

The full thesis in Acrobat pdf (1.5M) can be made available by contacting the author (pflegkas (at) uth.gr).