Abstract: When a ringlet with a high frame transfer quality is selected as a switching candidate for each station of a transfer destination from information on frame transfer quality for each ringlet, when it is determined that a fundamental ringlet is in a preceding stage of degradation of the frame transfer quality from information on the frame transfer quality of the fundamental ringlet, and if the fundamental ringlet is different from the switching candidate, a ringlet for transferring a frame to a station of the transfer destination is switched from the fundamental ringlet to the switching candidate.

Abstract: When a ringlet with a high frame transfer quality is selected as a switching candidate for each station of a transfer destination from information on frame transfer quality for each ringlet, when it is determined that a fundamental ringlet is in a preceding stage of degradation of the frame transfer quality from information on the frame transfer quality of the fundamental ringlet, and if the fundamental ringlet is different from the switching candidate, a ringlet for transferring a frame to a station of the transfer destination is switched from the fundamental ringlet to the switching candidate.

Abstract: In a testing apparatus for an optical access network, a converting unit converts an optical signal received through the optical access network into an electrical signal to create 10b coded data. A protocol processing unit performs a processing according to a protocol of the optical access network on the 10b coded data, and records a plurality of different protocol processing data corresponding to protocol information assigned to a plurality of ONUs. A memory unit stores the 10b coded data output from the converting unit. A CPU analyzes the 10b coded data in the memory unit.