On Overload Control and Performance Agreements in a Parlay/OSA Environment

Parlay/OSA is a service architecture for current and next generation telecommunication networks. A gateway provides the applications with abstracted network functionality via Application Programming Interfaces. This facilitates the creation of telecommunication services and applications from independent software developers. The gateway translates the requests for abstracted functionality to telecommunica­tion protocols and signalling. Parlay/OSA is a contract-based architec­ture where several constraints coexist. To fulfil the constraints and to deliver user-perceived QoS, overload control and other management mechanisms are needed. This thesis proposes and evaluates different overload control mech­anisms and other methods aiming to achieve conformance to Service Level Agreements. The investigated control mechanisms are mainly deployed at an external and separate physical entity. An external con­trol entity has some favourable properties such as providing robustness and supervisioning conformance to agreements. Performance agreements in general, and the implementation of such in a service architecture, are discussed. With an external control device it is important that this node itself is not overloaded. Therefore shaping algorithms and dimensioning for an external control node are investi­gated. Other important issues that are discussed are measurement strat­egies, overload control actions and how different priorities and time constraints should be handled