The authors consider technical options aimed at enhancing the reliability and availability of fiber-based local access connections (between local exchange and customer premises). Attention is paid both to point-to-point business connections and to point-to-multipoint fiber to the curb residential connections. The various alternatives are compared from the end-to-end channel availability point of view. The specific values regarding failure rates and times-to-repair come from experience gained within Telefonica's fiber network. Detailed Markov diagrams are given, making possible the evaluation of the effects that other figures of failure rates and times to repair would have on availability. The alternatives assessed include: connections with terminal-multiplexer redundancy; connections with terminal-multiplexers and cable-path redundancy; and connections with cable-path redundancy engineered with advanced photonic switching devices.
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