Source : Free On-Line Dictionary of Computing

Synchronous Optical NETwork
     
         (SONET) A {broadband} networking {standard} based
        on point-to-point {optical fibre} networks.  SONET will
        provide a high-bandwidth "pipe" to support {ATM}-based
        services.
     
        The SONET standard will establish a digital {hierarchical
        network} with a consistent worldwide transport scheme.  SONET
        has been designed to take advantage of fibre, in contrast to
        the {plain old telephone system} which was designed for copper
        wires.
     
        SONET carries {circuit-switched} data in {frames} at speeds in
        multiples of 51.84 megabits per second (Mbps) up to 48 * 51.84
        Mbps = 2.488 {gigabits} per second.  Since SONET uses multiple
        channels to transmit data, each SONET {frame} can be
        considered to be a two-dimensional table of bytes that is 9
        rows high and 90 columns deep.  For every {OC-n} level, SONET
        can transmit n number of frames at a given time.  Groups of
        frames are called {superframes}.
     
        SONET is the American version of {SDH}.
     
        [Wulf Losee; Corporate Computing 8.92; STACKS; LAN Magazine
        10.93].
     
        (1994-11-30)