Patent ID: 7764603

Claim:
A ringlet switching apparatus that selects a ringlet for a station of a transfer destination of a frame and switches from a ringlet for transferring a frame to other ringlet in a station of double ringlets in which a plurality of stations are connected in a ring shape with double paths for bidirectionally transferring frames, the ringlet switching apparatus comprising: an obtaining unit that obtains a frame flow rate indicating an amount of a frame transferred per unit time; a determining unit that determines whether a ringlet used for transferring the frame is in a preceding stage of a degradation of the frame transfer quality based on the frame flow rate for the ringlet used for transferring the frame obtained by the obtaining unit; a switching candidate selecting unit that obtains an increasing trend for each ringlet indicated by a difference between two frame flow rates obtained by the obtaining unit at two different times and selects a ringlet having a low increasing trend than other ringlet as a switching candidate for each station of the transfer destination; and a switching unit that switches a ringlet for transferring the frame to the station of the transfer destination from the ringlet used to the switching candidate selected by the switching candidate selecting unit when the determining unit determines that the ringlet used is in the preceding state and the ringlet used is different from the switching candidate selected.