Tele-Communication (Telecom) Terms Glossary and Dictionary
SONET/SDH: Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH)
The Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH), often combined as SONET/SDH, are a set of related standards for synchronous data transmission over fiber optic networks that are often used for framing and synchronization at the physical layer. SONET is the United States version of the standard published by the American National Standards Institutue (ANSI). SDH is the international version of the standard published by the International Telecommunications Union (ITU). Transmission rates of up to 10 Gbit/s can be achieved in today's SONET/SDH systems and the 40 Gbit/s systems are possible. SONET/SDH systems are fully compatiable with each other.