The increasing complexity of real-time systems has motivated the application of component-based software engineering principles during the last few years. Temporal encapsulation is key to smoothing the integration stage of software components in complex distributed hard real-time systems. This paper presents a network scheduling server algorithm to guarantee and at the same time limit the network bandwidth assigned to streams of messages with different real-time requirements in a fixed priority network. The algorithm is based on a recently corrected version of the POSIX sporadic server whose rules, originally intended for scheduling tasks, have been adapted and optimized for the special case of fixed-priority networks. The algorithm is able to provide bounded response times that can be analyzed with off-the-shelf real-time analysis tools and can be used for both synchronous and asynchronous messages. The proposed approach has been implemented and evaluated on real hardware, using the CAN bus. The performance evaluation results show that bandwidth isolation can be achieved with rather low overhead both on the processor and the network resources. 1.

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