Abstract
Three transport services are offered by FDDI: Asynchronous, Synchronous, and Isochronous (FDDI-II). In order to support the stringent multimedia (e.g., real-time video and voice) delay and bandwidth requirements the Asynchronous transfer service will not suffice. The Isochronous and Synchronous transport services differ considerably in their implementation, but the differences in the service provided can be made to appear transparent to many multimedia applications. It is shown that Synchronous traffic can support a wide range of application requirements efficiently at moderate cost when the connection between source and destination are on the same physical ring. However, Isochronous class traffic has advantages, particularly when the network traffic is well behaved (the peak data rate is close to the mean data rate) and when connections traverse multiple rings.