Digital transmission through optical fibres and 'packet-switching' are two independent technologies that have gained wide acceptance during the past decade. This paper considers the possibility of a fusion between the two technologies. The network envisaged is a long-haul, packet-switched network, with optical fibre links between the nodes, for the integrated transmission of voice and data. The advantages of implementing packetswitching on an optical fibre network are brought out. The proposed network effectively utilizes the bandwidth of 140 Mbit/s fibre optic links to transport voice and data packets in a store-and-forward manner from the source node to the destination node. The issues involved in the selection of routes for voice and data packets are discussed. Some standards and timing constraints have been evolved for the transmission of speech in packets. This imposes a limitation on the allowable delay at each node. The design of an ultra-fast packet-switch with high throughput, which satisfies the timing constraints, is described in this paper. Protocols for call set-up, priority rules, traffic flow and congestion control procedures are proposed and discussed. A simulation model of the packet-switch is developed, and its performance is evaluated for varying traffic conditions. The results of the simulation are presented. © 1987 SPIE. All rights reserved.