Network switching device and network switching method

The network switching device for transferring data between a plurality of networks, comprising:

• a plurality of reception interfaces respectively connected to a plurality of networks and receiving data from said plurality of networks;
• a buffer shared by said plurality of interfaces;
• a priority determination circuit which determines a priority of received data when the received data is input into said plurality of interfaces;
• an amount-of-use detection circuit which determines whether or not an amount of current use of said shared buffer exceeds a threshold value which is associated with each priority in advance;
• and
• a data transfer circuit which acquires results of determination by said priority determination circuit and said amount-of-use detection circuit, and stores said received data in said shared buffer when said amount of current use of the shared buffer does not exceed the threshold value associated with said priority of the received data.

A network switching method for transferring data between a plurality of networks by storing input data in a buffer, comprising the steps of:

• (a) determining a priority of received data from said plurality of network when the received data is input;
• (b) determining whether or not an amount of current use of said buffer exceeds a threshold value which is associated with each priority in advance;
• and
• (c) storing said received data in said buffer when said amount of current use of said buffer does not exceed the threshold value associated with said priority of the received data.