| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize optimum selection control to an ISDN line required for bulk transfer and important call control in response to a bypass circuit band with respect to a relay line backup technology using the ISDN line on the occurrence of a fault of a relay line between nodes or the like. SOLUTION: A node 101(#B) uses a representative selection function at an ISDN exchange to select an ISDN line for backup through which bulk transfer for pluralities of B channels is executed from pluralities of ISDN lines set by a node 101 (#A). In this case, the two nodes 101 (#A, #B) exchange a slave number of an ISDN line to be selected and number of B channels for bulk transfer are exchanged as user-user information in a D channel message of the ISDN line and select the ISDN line based thereon.</p> |
