We present a method for providing hard real-time guarantees for traffic through an Asynchronous Transfer Mode (ATM) network. Guaranteed delivery Also implies that we have to guarantee that no cells are lost due to over-full buyers in the network.

By using priority queues in the output buyers we allow urgent messages short end-to-end delays, while still guaranteeing end-to-end delays for low-priority messages.

We can determine _a priori if message deadlines will be met by calculating maximum end-to-end delays and buyer-needs. Analysis is based on CPU schedulability analysis, which means that it provides a framework for analysing an entire system, including both CPU and network scheduling.