Network connection apparatus

A network connection apparatus connected between a plurality of networks for transferring, to a destination node belonging to one of the networks, a transmission frame output from a sender node belonging to another network, the transmission frame including a destination address, a sender address and transmission data, comprising:

• a common memory for temporarily storing transmission frames;
• a plurality of network control sections each for writing into the common memory a transmission frame output from that one of the networks which is connected thereto, outputting a notification to notify start of writing and a notification to notify completion of normal writing, and reading the transmission frame written in the common memory in response to a transmission command, so as to transmit the transmission frame to the network connected thereto;
• a network switch circuit interposed between each network and a corresponding network control section for connecting the each network and the corresponding network control section in a normal state, and directly transmitting a transmission frame output from a sender network, to a destination network when receiving a bypass command which designates the destination network and the sender network;
• means for setting the operation mode of the network connection apparatus to a Cut Through Mode or a Store & Forward Mode;
• means operative in the Cut Through Mode for receiving from each network control section the notification to notify start of writing, and transmitting to the network switch circuit the bypass command which designates the destination network and the sender network determined by the destination address and the sender address included in the transmission frame, respectively;
• and
• means operative in the Store & Forward Mode for receiving from each network control section the notification to notify completion of normal writing, and transmitting the transmission command to that one of the network control sections which is connected to the destination network determined by the destination address included in the transmission frame.

A network connection apparatus connected between a plurality of networks for transferring, to a destination node belonging to one of the networks, a transmission frame output from a sender node belonging to another network, the transmission frame including a destination address, a sender address and transmission data, comprising:

• a common memory for temporarily storing transmission frames;
• a plurality of network control sections each for writing into the common memory a transmission frame output from each network, outputting a notification to notify start of writing and a notification to notify completion of normal writing, and reading the transmission frame written in the common memory in response to a transmission command, so as to transmit the transmission frame to a designated destination network;
• monitor means for monitoring the operation state of each network control section;
• a network switch circuit interposed between each network and each network control section for connecting, when receiving a transmission frame from one of the networks, the one network to that one of the network control sections which is determined by the monitor means to be in a lightly loaded state, and directly transmitting, when receiving a bypass command which designates a destination network and a sender network, a transmission frame output from the sender network, to the destination network;
• means for setting the operation mode of the network connection apparatus to a Cut Through Mode or a Store & Forward Mode;
• means operative in the Cut Through Mode for receiving from each network control section the notification to notify start of writing, and transmitting to the network switch circuit the bypass command which designates the destination network and the sender network determined by the destination address and the sender address included in the transmission frame, respectively;
• and
• means operative in the Store & Forward Mode for receiving from each network control section the notification to notify completion of normal writing, and transmitting a transmission command to another each network control section.

A network connection apparatus connected between a plurality of networks for transferring, to a destination node belonging to one of the networks, a transmission frame output from a sender node belonging to another network, the transmission frame including a destination address, a sender address and transmission data, comprising:

• a common memory for temporarily storing transmission frames;
• a plurality of network control sections each for writing into the common memory a transmission frame output from each network, and reading the transmission frame written in the common memory, and outputting the read transmission frame to a designated destination network;
• monitor means for monitoring the operation state of each network control section;
• and
• a network switch circuit interposed between each network and each network control section for connecting, when receiving a transmission frame from one of the networks, the one network to that one of the network control sections which is determined by the monitor means to be in a lightly loaded state.