Access network systems which form a sophisticated information infrastructure have been developed to enable fiber to the home (FTTH) to be implemented and to supply multimedia services in Japan. Advanced operation systems (OpS) which can operate, administer and maintain the communication network must be constructed for these advanced info-communication services. We have proposed an access network OpS based on the platform concept. However, it is expected that there will be various kinds of access network task and their number will increase with the progress of optical technologies. Therefore access network OpS must be able to process these tasks reliably and efficiently. In this paper, we propose both highly reliable and very efficient constructions for a previously reported distributed OpS platform (PF). Then we discuss the methods for shifting access network tasks from an overloaded computer to another computer. Then the proposed constructions are realized and their abilities are compared. Finally, to realize the proposed constructions, we also propose three methods for collecting the computer load data when the PF transacts access network tasks.

A bidirectional system using 1.3 mu m lasers as a transmitter and a receiver are investigated. The lasers considered are commercially available Fabry-Perot and distributed-feedback lasers. It is found that the poor performance of a laser receiver, compared to a PIN receiver, stems from three factors: low responsivity, high capacitance, and polarization dependence of responsivity, high capacitance, and polarization dependence of responsivity. The effect of each factor is evaluated. It has been clarified that the polarization dependence of sensitivity originates from the TE and TM modes dependence of both mode confinement factor and reflection at a facet. Using the measured parameters, 1.3- mu m laser receiver sensitivity for a 10/sup -9/ error rate is estimated. Burst data transmission experiments show that estimated sensitivities agree well with the measured values. Optical ping-pong transmission distance of narrowband services is determined based on estimated sensitivity.>