| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce delay in switchback of communication paths. <P>SOLUTION: A communication device 1-1 transmits a path confirmation request signal for confirming a state of a main path 2. In the case that no response signal is received to the path confirmation request signal after the response signal to the path confirmation request signal is received, an abnormality counter 15 is started to count from an initial value calculated based on a correction value and a value of a normal counter 14. When the value of the abnormality counter 15 becomes a switching threshold or more, a path is switched over from the main path 2 to an alternative path 3. In the case that the response signal is received to the path confirmation request signal after no response signal is received to the path confirmation request signal, the correction value is calculated based on a response time period measured by a timer 16, a current correction value, and a current value of the abnormality counter 15. When the value of the normal counter 14 is equal to or more than a value obtained by adding the calculated correction value and a switchback threshold, the path is switched back from the alternative path 3 to the main path 2. <P>COPYRIGHT: (C)2012,JPO&INPIT |
