Most of the solutions proposed to support real-time (i.e. guaranteed performance) communication services in packet-switching networks adopt a connection-oriented and reservation-oriented approach. In such an approach, resource allocation and route selection decisions are made before the start of the communication on the basis of resource availability and real-time network load at that time, and are usually kept for the duration of the communication. This rather static resource management approach has certain limitations: it does not take into account (a) the dynamicity of the communicating clients; (b) the dynamicity of the network state; and (c) the tradeoff between quality of service and network availability, thus affecting the availability and flexibility of the real-time network services. Availability is the ability of the network to accommodate as many real-time clients as possible, while flexibility is the ability to adapt the real-time services to changing network state and cli...