Patent ID: 7177283

Claim:
A transmitting and receiving circuit comprising: a plurality of transceivers for transmitting and receiving data to and from a facing node at plural different data transfer speeds; and a speed setting circuit which detects a data transfer speed in a channel between nodes and sets a maximum data transfer speed in accordance with a thus detected value with respect to each of the transceivers, wherein said speed setting circuit includes: a negotiation circuit, connected to each of the transceivers, which executes a speed negotiation for finding a maximum value of the data transfer speed in the channel between the nodes; and a data transfer speed setting circuit which sets the maximum value of the data transfer speed, obtained as a result of the speed negotiation by said negotiation circuit, as the maximum data transfer speed with respect to each of the transceivers, only in case where the maximum value is different from each maximum data transfer speed obtained from each transfer possible speed of the transceivers and each transfer possible speed of respective facing transceivers.