Communications network

A communications system comprising a plurality of communications nodes at each of a plurality of locations and a plurality of communications channels extending between nodes at different locations, at least some of the nodes including processing means, and a communications network for providing communications among the processing means, the communications network comprising:

• at each location, a first unidirectional communications loop coupling together the processing means at that location;
• and
• a plurality of second unidirectional communication loops, provided on said communications channels, each coupling together a plurality of processing means at different locations;
• at least one processing means at each location thereby being coupled to one of the first and one of the second unidirectional communications loops, each such processing means including means for supplying the same information simultaneously to both of the loops to which it is coupled, and means for receiving information from each of the loops to which it is coupled.