| 摘要 |
PURPOSE:To inform path terminating equipments of all paths of path trouble by generating a warning carrying information block where a warning indicating the number and trouble contents of a path is written by a transmitter which detects the abnormality of a transmission line and sending it out to adjacent transmitters. CONSTITUTION:If abnormality occurs on a transmission line 301b as shown by X, the transmitter 72 searches a path control table for all virtual paths put in the transmission line 301b where the abnormality occurs. Then the information block which carries respective display bits VPI and the warning AIS indicating the path trouble is generated and sent out to terminating devices 52a, 52b, and 52c for the respective virtual paths. Consequently, the information block which carries the AIS is transmitted to respective transmission lines 202a-202c and 102a-102c. Therefore, terminating equipments for all paths where trouble occurs can be informed of the trouble of the path.
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