Patent ID: 6975646

Claim:
A network interconnection system comprising: a plurality of input and output ports that are connected to different networks; an input interface connected to each of the input ports, wherein, when an input signal is not a signal of a predetermined signal format, the input interface converts the input signal to an interim packet signal, wherein a form of the interim packet signal is identical to the predetermined signal format and a content of a predetermined portion of the interim packet signal is different from a counterpart of any packet signal of the predetermined signal format; an output interface connected to each of the output ports, wherein, when receiving an interim packet signal as an output signal, the output interface converts the interim packet signal to a signal conforming to a corresponding network; and a switch for forwarding an interim packet signal received from one of input interfaces to an appropriate one of output interfaces based on a destination of an original signal of the received interim packet signal, wherein a signal of the predetermined signal format is an Ethernet packet signal, wherein the predetermined portion of the interim packet signal corresponding to a source address of the Ethernet packet signal is set to a unique bit string that is not used in Ethernet packet format.