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A distributed routing algorithm for an integrated network with circuit and packet switching capabilities is proposed. The algorithm is based on the ideas of a minimum-delay routing algorithm proposed by Gallager. The trunk organisation used in the integrated network allows a fixed or moving boundary between circuit and packet traffic. The proposed routing algorithm operates independently of the trunk management policy, and attempts to maximise a network performance measure M. This measure reflects both the end-to-end blocking for circuit traffic and the average end-to-end delay for packets. It will be shown that, for optimal performance, packet traffic must be routed in the direction of minimum incremental link delay to the packet destination. Circuit routing, on the other hand, depends on whether the trunk boundary is fixed or movable. Thus, under the fixed-boundary management policy, circuit traffic must be routed in the direction of minimum incremental link blocking to the circuit destination. Under the moving-boundary management policy, circuit routes must be chosen to minimise the effect on packet performance, i.e. minimum incremental packet delay due to incremental circuit traffic. The proposed routing algorithm has been tested for its adaptability to various load conditions. These investigations have also demonstrated the performance improvement due to the moving-boundary trunk organisation.