ATM SWITCHBOARD

PROBLEM TO BE SOLVED: To obtain an ATM switchboard for routing an IP packet by adding an IP routing processing part to an existing ATM switchboard. SOLUTION: An IP routing processing part 13 is added to an existing ATM switchboard. Relating to this switchboard, line housing parts 11-1 and 11-2 transmit ATM cells to an ATM switch 12. The ATM switch 12 outputs the received ATM cells to an IP routing processing part 13 according to switching information preset by a switch control part 14. The IP routing processing part 13 reads IP header information from the received ATM cells, and decides a virtual line being the destination of the transfer of an IP packet before the ATM cell integration of the ATM cells based on the information, and transmits the ATM cells to the virtual line. The transferred ATM cells are transferred to the ATM switch 12 again, and transmitted through ATM line housing parts 11-1-11-2 to an IP network 2-1 or 2-2 again.