Fibre-Ribbon Ring Network with Inherent Support for Earliest Deadline First Message Scheduling

This paper presents a network with earliest deadline first (EDF) scheduling on a per slot basis. The network is called CCR-EDF (Control Channel based Ring network with EDF scheduling). The topology is a pipelined unidirectional fibre-ribbon ring that supports several simultaneous transmissions in non-overlapping segments and with dedicated fibres for clock and arbitration. In each slot the node that has highest priority generates the clock. The clock hand over strategy together with the scheduling feature gives the network the functionality for earliest deadline scheduling of periodic messages belonging to logical real-time connections. Logical realtime connections may be added and removed during runtime, through admission control. Guaranteed realtime communication service is supported to the user. Other services include best effort traffic and special services for parallel and distributed processing such as barrier synchronisation and global reduction.