<p>The switch includes a main store control unit with at least one comparator unit (2-5) which is arranged in front of the main store. The comparator acts with a counter (1) and a control logic so that when a predetermined threshold (Ldisc) for the fill level of the main store is obtained a predetermined number of connections (VC) are defined based on the sequence of arrival of ATM cells assigned to the connections. Each ATM cell of a packet belonging to the connection value to be defined is erased before arrival in the main store. Preferably, the comparator is connected with an erasure table (15) which includes the connection identifications of the frames to be erased. The erasure table activates the erasure of each arriving ATM cell whose connection identification is stored in the erasure table.</p>
