PURPOSE: To improve the communication processing capability of an equipment side up to its own limit by connecting plural LAN interface devices to one device so as to decentralize a load.

CONSTITUTION: An ARP request received by a LAN controller LCP30-1 in which the reception of a multiple address frame is allowed is given to an ARP processing section 24. The processing section 24 checks whether or not an inter- net address in an ARP request is coincident with its own address. When dissident, the ARP request is aborted. On the other hand, when coincident, a load table 22 is referenced and the LCP with a least load is selected as an ARP request reply source among LCP30-1-30-n (e.g. LCP30-n). The processing section 24 generates the ARP reply taking the LAN address of the LCP 30-n as a sender address. A reply of sending the generated ARP reply to a LAN cable 11 is requested to the LCP30-n via a bus 12-n.