Incrementally expandable ring architecture for providing telephony services

摘要

A telecommunications network is formed from a plurality of interlocked rings. Each interlocked ring includes two switching nodes such that adjacent pairs of interlocked rings have a switching node in common. The interlocked ring also includes first and second telecommunications links that connect the two switching nodes. The first and second telecommunications links include at least one optical fiber adapted for transporting a plurality of wavelength division multiplexed optical channels. Each of the plurality of optical channels is defined by a different wavelength. The first telecommunications link includes at least one branching unit disposed along the at least one optical fiber. The branching unit is adapted to pass predetermined ones of the plurality of optical channels between the switching nodes. The branching unit includes at least one add-drop multiplexer for adding and dropping predetermined ones of the plurality of optical channels to and from a terminal coupled to the branching unit. To provide fault tolerance, at least one of the interlocked rings may further include additional telecommunications links to perform line or path switching.