SYSTEM CHANGEOVER SYSTEM FOR SWITCH IN ATM EXCHANGE

PROBLEM TO BE SOLVED: To realize changeover of an uninterruptible system in which loss of an active system cell, duplicated active system cells and inverted sequence of the active system cell are prevented in the case of changeover of ATM switches in duplicate. SOLUTION: The system is provided with an ACT(active/complementary transmission) bit provision section 102 providing an exclusive ACT bit to a cell 103 received by ATM switches 101 in duplicate. A cell selector 110 is provided to an output of the ATM switches 101 and the selector 110 pass through cells passing through an active system switch. Furthermore, when an active ATM switch is selected from a standby ATM switch, an output of the switch is tentatively stopped. Since ACT bits exclusive to both system input cells are provided, loss and duplicate of active cells are prevented at system changeover. Furthermore, the reversed sequence of active cells on the occurrence of system changeover is prevented by stopping tentatively the switch output.