Pdh vs sdh describes difference between pdh and sdh

SONET vs SDH

SONET/SDH is the dominant technology deployed in most metro and long distance networks. It refers to a group of fiber optic transmission rates that can transport digital signals with different capacities. Since their emergence from standards bodies around 1990, SDH and its variant SONET (used in North America), have tremendously enhanced the performance of telecommunications networks based on optical fibers. The basic unit of SDH is synchronous transmission module level-1(STM-1). The basic unit of SONET is Optical Carrier level-1(OC-1). The other rates OC-3,OC-12,OC-18,OC-24,OC-36,OC-48,OC-96 and OC-192 are derived from this basic rate.