SONET—Synchronous Optical Network

Synchronous optical network (SONET) equipment aggregates many types of traffic into uniform streams onto fiber optic cabling. SONET is capable of transporting traffic in redundant rings. Fifty percent of the rings' capacity is set aside for automatic restoral. If one section of the ring is cut, traffic automatically travels on the redundant fiber in the ring. Bellcore, the central research group jointly owned at that time by the RBOCs, introduced SONET in 1984. The ITU has approved standards for OC speeds. The various OC levels and their speeds are shown in Table 6.5.

When it was developed, SONET was envisioned as carrying synchronous traffic such as T-1, E-1, T-3 and E-3 as well as slower rates uniformly on ...

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