| 摘要 |
PROBLEM TO BE SOLVED: To reduce a data transfer delay time by allowing the hub to consist of a device that loads a frame number and a reception port number after a frame sender address and of a register denoting a cross reference between a frame number and a transmission available port number and starting transmission of a frame only to a port permitted by the register. SOLUTION: Upon the receipt of a frame from communication control LSIs 109, 110, data transfer control sections 105, 107 add a frame number and a reception port number just after a sender address and provide an output of the result to a common share bus 104. An address retrieval section 102 receives a frame to extract the destination address, the frame number and the reception port number and retrieves a destination port from a CAM 103 and writes a cross reference between the extracted frame number and a destination port number to which transmission is permitted to a port number cross reference register 101. Since a time required for a retrieval time and notice of the destination port number is saved, the transfer time is reduced.
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