Real-time traffic in FDDI-II packet switching vs. circuit switching

The pros and cons are discussed of synchronous and isochronous service in FDDI-II, which is an enhanced version of the Fiber Distributed Data Interface (FDDI) protocol. The results make clear that basic FDDI meets the requirements imposed by traditional LAN applications. To overcome the problem of throughput degradation and increasing delays for asynchronous traffic in applications with large fiber length and hard response time requirements, FDDI-II is defined as a promising upward-compatible extension. It is shown that from a performance point of view FDDI-II is an excellent candidate for complex communications environments. This protocol integrates both circuit switched and packet switched services in an efficient way. The results show that, in environments with upcoming hard real-time requirements, changing to the enhanced protocol, i.e., changing from basic FDDI to FDDI-II, is a much better way to meet the demands than to push the old protocol to its limits