A novel passive protected SONET bidirectional self-healing ring architecture

Among SONET ring alternatives, the four-fiber bidirectional self-healing ring architecture (BSHR/4) has the highest available capacity and can work with today´s systems with minimum change. A cost-effective implementation for a BSHR/4 which uses a totally passive ring as the protection ring of the BSHR/4 is presented. The ring uses a SONET ring to carry working traffic and a passive ring to carry protection traffic in case of network component failures. The passive ring, which is composed of optical switches and optical amplifiers, is essentially an optical add-drop protection ring. The optical signal add-drop is controlled by SONET add-drop multiplexers using existing SONET self-healing protocols. A SONET control scheme for this implementation is also discussed. The proposed BSHR/4 not only has a significant cost advantage over conventional implementations, but also can easily evolve from any two-fiber ring, with a minimum capital investment and offering twice the capacity