Router for high-speed packet communication between terminal apparatuses in different LANs

In a router (20) having a routing section (22) for performing routing on the basis of a routing table (11) and an ARP (address resolution protocol) table (12) to transmit a received packet to a destination, and adapted to connect a plurality of local area networks (LANs), to realize high-speed routing, the IP addresses and MAC addresses of the terminal apparatuses in the LANs directly connected to the router (20) are stored in a memory table (23) in correspondence with the interfaces information to which the LANs are connected, together with the IP addresses of the terminal apparatuses in a LAN connected to the router (20) through another router, the MAC address of another router, and the interfaces information to which another router is connected, which are stored in correspondence with each other. When a packet determination section (25) determines that a received packet satisfies predetermined conditions, and a registration determination section (29) determines that destination IP address of the packet is registered in the memory table (23), a second routing section (30) specially designed for packets satisfying the predetermined conditions reads out information corresponding to the IP address from the memory table (23), updates the MAC address of the received packet with the information, and outputs the packet.