Ring-type communication network

A network for carrying digital data among a plurality of data generating devices and data using devices, comprising:

• a plurality of nodes, each said device being associated with one of said nodes,
• a plurality of optical fiber links interconnecting said nodes to form a continuous ring,
• said optical fiber links being arranged to carry light modulated in accordance with bit values corresponding to said digital data,
• said nodes being arranged to cause said bit values to appear on said links in a succession of bit intervals, one bit value per bit interval, said nodes being further arranged to cause said bit intervals to define a plurality of available independent communication bands for carrying said digital data, each said band being represented by a series of spaced apart individual said bit intervals, wherein said nodes are further arranged to organize said bit intervals into a series of frames, each said frame comprising a plurality of successive said bit intervals, no more than one said bit interval for each said band appearing in any said frame, and wherein said nodes are further arranged to group said frames into blocks, each said band comprising one said bit interval in each of more than one said frame of each said block, said different bit intervals of each said band representing different available independent communication channels.