Synchronous Optical Network

Abbreviated SONET. A set of fiber-optic-based communications standards with transmission rates from 51.84Mbps to 13.22Gbps.

First proposed by Bellcore in the mid-1980s, SONET was standardized by ANSI, and the ITU adapted SONET in creating the worldwide Synchronous Digital Hierarchy (SDH) standard.

SONET uses synchronous transmissions in which individual channels (called tributaries) are merged into higher-level channels using time-division multiplexing techniques. Data is carried in frames of 810 bytes, which also includes control information known as the overhead.

See also Optical Carrier; Synchronous Digital Hierarchy.