DEVICE AND PROGRAM FOR SWITCHING RINGLET

PROBLEM TO BE SOLVED: To provide a device and a program for switching a ringlet, which are capable of properly selecting ringlets of high frame transfer quality (kept free from convergence or trouble) and switching to the selected ringlets with proper timing (before the occurrence of convergence or trouble). SOLUTION: A ringlet of higher frame transfer quality is selected out as a switching hypothesis for each transfer destination on the basis of information as to the frame transfer quality of each ringlet, and when it is judged from information as to the frame transfer quality of a principle ringlet (a ringlet that is transferred to a transfer station via stations smaller in number) that the frame transfer quality of the principle ringlet is in a degradation prestage, if the principle ringlet is different from a switching hypothesis, the ringlet which transfers a frame to a transfer destination is switched from the principle ringlet to a switching hypothesis. COPYRIGHT: (C)2008,JPO&INPIT