| 摘要 |
<P>PROBLEM TO BE SOLVED: To carry out a return test, by designating an arbitrary transmission device, regarding a data transmission system which connects a plurality of transmission devices by a transmission path, and to provide a test control method. <P>SOLUTION: A data transmission system is configured, such that a plurality of transmission devices 1-7 are sequentially connected in a serial manner by a transmission path. In the data transmission system and a test control method, control information, comprising request information and designation information is set in an overhead of a transmission frame; a target transmission device is designated by the designation information; and a formation request or a release request of a return loop is designated by the request information. The transmission device, receiving the control information determines that it is a designation by own device, when the designation information becomes "0" after executing decrement processing of the designation information and allows the control part 12 to control a return-loop forming part 11, in accordance with the request information and to execute control for formation or release of the return loop; the transmission device transfers control information to the next transmission device, with all the control information set to "0", or transfers the control information, as it is, to the next transmission device, when the control information does not becomes "0". <P>COPYRIGHT: (C)2010,JPO&INPIT |
