Patent ID: 7626934

Claim:
A packet transfer apparatus that connects a first communication network including a plurality of terminals and a plurality of second communication networks including servers for offering communication services so that packets can be transferred between said terminals and said servers, said packet transfer apparatus comprising: a plurality of channel interfaces through which said packets are transmitted and received between said first and second communication networks; a protocol processor to convert the format of said packets received through said channel interfaces and to make a process for the transfer of said packets between said channel interfaces and other processes for communication; and a controller for controlling said whole packet transfer apparatus, wherein mode a judgment table having information of ordering to respond or not to a certain one of said packets received from said first communication network is provided in said protocol processor through said controller, wherein said certain packet received from said terminals is processed or discarded on the basis of said information, such that when said certain packet is processed, said certain packet is transferred from said terminals to said servers after a communication procedure that follows the reception of said certain packet is continuously performed to connect said terminals and said servers through said first and second communication networks, while when said certain packet is discarded, said communication procedure is stopped from continuing after said certain packet is discarded, wherein said communication procedure is a PPPoE (Point to Point Protocol over Ethernet) communication procedure defined in RFC 2516 of IETE (Internet Engineering Task Force Request for Comments No. 2516), and makes a PPP (Point to Point Protocol) session be established between said terminals on said first communication network side and said packet transfer apparatus, wherein said certain packet is a PADI (PPPoE Active Discovery Initiation) packet, and when said communication procedure is continued, a PADO (PPPoE Active Discovery Offer) packet is transmitted back to said terminal, and wherein when said PADI packet from said terminals does not have a length of an identifier specified in association with a communication service offered by said server, said protocol processor decides to transmit said PADO packet back to said terminal or discard said PADI packet on the basis of said information provided in said mode judgment table of said protocol processor.