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synchronous optical network (SONET)

Synchronous Optical Network (SONET) is a high-speed network with transmission speeds from 12.0 Mbit/s up to 2.5 Gbit/s.

Sonet was developed by the American Bell Laboratories and is based on single-stage multiplexing. It is a synchronous transmission method for wide area networks, from which the ITU standard for the Synchronous Digital Hierarchy (SDH) emerged in 1988. Sonet describes the transmission frame of OSI layer 1 and is used as a transport medium for ATM. In Sonet, transmission rates, coding schemes and bit rate hierarchies are standardized.

Sonet hierarchy with DS capacities

Sonet hierarchy with DS capacities

The Sonet and SDH specifications are identical except for minor variations in the header of a frame. Both technologies use the same transmission rates. In Sonet, the frame is called Synchronous Transport Signal (STS), which is equivalent to Optical Carrier (OC) in its speeds.

Transmission Rates of Sonet and SDH

Transmission Rates of Sonet and SDH

The base bit rate of the North American Sonet hierarchy is STS-1 or OC-1 at 51.840 Mbps. Below that, there are STS-1/2 and STS-1/4, but no OC tier. Above that, there are STS and OC 3, 9, 12, 18, 24, 36, and 48 multiplex stages.

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Englisch: synchronous optical network - SONET
Updated at: 20.04.2012
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