SONET/SDH (Synchronous Digital Hierarchy)

SONET (Synchronous Optical Network) and SDH (Synchronous Digital Hierarchy) are international standards for transmitting multiple digital data streams over optical fiber at high speeds. They synchronize data transfer, allowing many signals—like phone calls, internet data, and video—to be combined and sent efficiently on a single fiber. This synchronized timing ensures reliable, quality transmission and easy management of large data volumes across long distances, making modern telecommunications and internet infrastructure more robust and scalable.