Patent ID: 6785225
Filing Date: 2004-08-31
Classification: H04J

Abstract:
A communication apparatus which is connected with a network comprising:(i) lower-layer apparatuses which are connected with communication lines of a lower layer and communication lines of an upper layer, each lower-layer apparatus having means for line switching in the lower layer; (ii) upper-layer apparatuses which are connected with the communication lines of the upper layer and have means for line switching in the upper layer, wherein said lower-layer apparatus transmits a switching-inhibit signal to the upper-layer apparatuses when said lower-layer apparatus has detected a line failure, in a lower or upper layer communication line identifies one or more faulty lines of the lower or the upper layer and locates the site of occurrence of failure by using failure information collected on the lower and upper-layer communication lines, cancels the switching-inhibit signal to the upper-layer apparatuses when no lower-layer communication line has been found faulty but an upper-layer communication line has been found faulty,; determines, by using failure information concerning the lower and upper-layer communication lines, which line-switching means of the lower and upper-layer apparatuses should perform switching in order to secure a largest number of normal upper-layer communication lines, or in order to restore high-priority lines rather than low-priority lines, or in order to secure a largest number of signal channels, in case that any of the lower-layer communication lines has been found faulty; and means for causing line switching in the lower layer first and then canceling the switching-inhibit signal to the upper-layer apparatuses when switching is to take place in both the lower and upper layers in accordance with said determination.