Section 8.1: From Copper to Fiber

Synchronous Optical Network (SONET) provides bandwidth in the gigabits, far beyond the capacity of the digital hierarchy. In fact, a DS1's capacity is 1.544 Mbps, based on 64-kbps channels. An OC1 is the lowest signal in the optical hierarchy, and it supports 51.840 Mbps of bandwidth. An OC48 supports 2.488 Gbps, the equivalent of 1344 DS1s.

Before SONET was developed, fiber equipment and their interfaces were highly propriety. This prevented companies from connecting their fiber equipment to other vendor's equipment. SONET changes this by providing a standardized interface that all vendors adhere to. Telephone companies, cable television operators, and power utility companies have already invested heavily in SONET networks.

SONET was developed by the Exchange Carriers Standards Association (ECSA) for the American National Standards Institute (ANSI). The European equivalent to SONET is the Synchronous Digital Hierarchy (SDH). There are subtle differences between the two. SONET got its beginnings around 1984, when the ECSA was asked by the Interexchange Carriers Compatibility Forum (ICCF) to create a standard for connecting fiber optic transmission equipment from different vendors together. This was important because many new carriers were trying to connect to existing fiber networks but were unable to interwork their equipment because of the lack of standards.

Bellcore extended the concept into standardization of all fiber optic network elements, including multiplexers and Digital Cross Connects. Today's standards cover all aspects of fiber optics in both public and private networks. Many universities are using SONET as their campus...