(pronounced “SAH-net”) (n.) A broadband networking standard based on point-to-point optical fiber networks. The standard provides a high-bandwidth pipe to support services based on Asynchronous Transfer Mode (ATM). SONET establishes a digital hierarchical network with a consistent transport scheme. It has been optimized for fiber, in contrast to the plain old telephone system (POTS), which was designed for copper wires. SONET carries circuit-switched data in frames at speeds up to 48 gigabits per second (Gbps) in multiples of 51.84 megabits per second (Mbps). Each SONET frame is a two-dimensional table of bytes 9 rows high and 90 columns deep. Groups of frames are called superframes.
Data transfer rates at different levels of SONET are shown below:
OC-1 52 Mbps 28 DS-1 or 1 DS-3
OC-3 155 Mbps 84 DS-1 or 3 DS-3
OC-9 466 Mbps 252 DS-1 or 9 DS-3
OC-12 622 Mbps 336 DS-1 or 12 DS-3
OC-18 933 Mbps 504 DS-1 or 18 DS-3
OC-24 1.2 Gbps 672 DS-1 or 24 DS-3
OC-36 1.9 Gbps 1008 DS-1 or 36 DS-3
OC-48 2.5 Gbps 1344 DS-1 or 48 DS-3