SONET
Edit Watch this page Read in another language Synchronous optical networking Page issues Synchronous optical networking ( SONET ) and synchronous digital hierarchy ( SDH ) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). At low transmission rates data can also be transferred via an electrical interface. The method was developed to replace the plesiochronous digital hierarchy (PDH) system for transporting large amounts of telephone calls and data traffic over the same fiber without synchronization problems. SONET and SDH, which are essentially the same, were originally designed to transport circuit mode communications (e.g., DS1 , DS3 ) from a variety of different sources, but they were primarily designed to support real-time, uncompressed, circuit-switched voice encoded in PCM format. [1] The prim