Importance

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Abstract

In a data packet switching apparatus for switching a data packet, arriving from a plurality of incoming virtual connections in the form of logically multiplexed cells, to a plurality of outgoing virtual connections, efficient use is made of a buffer under congestion. A required data buffer plane quantity monitoring/calculation circuit calculates the number of required data buffer planes (segments) from the packet length contained in the starting cell data, and a packet reception allow/disallow decision/buffer plane quantity securing circuit compares it with the remaining buffer amount. If the number of required buffer planes is larger than the remaining buffer amount, all cell data belonging to the packet are discarded. If the number of required buffer planes is not larger than the remaining buffer amount, the required buffer is presecured by reducing the remaining buffer amount by an amount equivalent to the number of required buffer planes. In a second aspect of the present invention, a unique transmission number is appended to cell data belonging to the packet whose outgoing virtual connection has been determined, the transmission number remaining appended to the cell data until it is transmitted out. The cell data stored in the buffer is output from the buffer for transmission based on the thus determined outgoing virtual connection and the transmission number.

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First Claim