SONET

ISP & telecom

Stands for: Synchronous Optical Network (SDH internationally)

Synchronous Optical Network - the telco standard that made optical transport a synchronized hierarchy with 50-millisecond healing rings. SDH is its international twin.

SONET (ANSI/Telcordia, North America) and SDH (ITU-T G.707, everywhere else) organized fiber transport into a rigid TDM hierarchy built from the 51.84 Mb/s STS-1, with add/drop multiplexers on protected rings that restored service within 50 ms of a fiber cut - the number that defined carrier-grade for a generation. Voice, ATM, and packet links all rode inside its containers. Packet-optical transport and OTN have largely displaced it, but its framing, its OAM discipline, and the 50 ms reflex still shape how operators think.

Also known as: sonet, sdh, synchronous optical network, synchronous digital hierarchy, adm, sts-1

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