Chapter 16 A pipelined fiber - ribbon ring network with heterogeneous real - time support

This paper presents a fiber-optic ring network with support for heterogeneous real-time communication. The CCR-EDF (Control Channel Ring network with Earliest Deadline First scheduling) network is an optical fibre-ribbon pipelined ring network with a separate channel for network arbitration. The medium access protocol, that uses the control channel, provides low-level support for hard real time traffic and group communication functions such as barrier synchronisation and global reduction. The topology of the network is a pipelined unidirectional fibre-ribbon ring that supports several simultaneous transmissions in non-overlapping segments. Access to the network is divided into timeslots. In each slot the node that has the highest priority message is permitted to transmit. The novel medium access protocol uses the deadline information of individual packets, queued for sending in each node, to make decisions, in a master node, about who gets to send. This feature of the medium access protocol gives the network the functionality for earliest deadline first scheduling. Different classes of traffic are supported for the user. These are guaranteed