Patent ID: 7623513

Claim:
A communication system comprising: a first information processor; a second information processor; a first communication control unit for controlling the communication of the first information processor; a server; and a second communication control unit for controlling the communication of the second information processor, wherein the first information processor includes: a bubble packet transmitter for transmitting a bubble packet for leaving transmission record in the first communication control unit to the second communication control unit via the first communication control unit; a reply packet receiver for receiving a reply packet transmitted from the second information processor via the second communication control unit to a bubble packet transmitting port, a port of the first communication control unit, which is used in transmission of the bubble packet; a range detection packet transmitter for transmitting a range detection packet used for detecting a range of ports including the bubble packet transmitting port to the server, and a port number differential detection packet transmitter for transmitting a port number differential detection packet for detecting a port number differential in the first communication control unit to the server via the first communication control unit, the server includes: a range detector which receives the range detection packet for detecting the range of ports including the bubble packet transmitting port in accordance with the range detection packet; a range transmitter for transmitting range information detected by the range detector as information showing the range of ports including the bubble packet transmitting port to the second information processor, a port number differential detector which receives the port number differential detection packet for detecting a port number differential in the first communication control unit in accordance with the port number differential detection packet; and a port number differential information transmitter for transmitting port number differential information detected by the port number differential detector as information showing the port number differential of the first communication control unit to the second information processor, the second information processor includes: a reply packet transmitter for transmitting the reply packet to one or more ports including at least the bubble packet transmitting port; a range receiver for receiving the range information; and a port number differential information receiver for receiving the port number differential information, and wherein the reply packet transmitter transmits the reply packet to ports in a range indicated by the range information; and the reply packet transmitter transmits the reply packet every port number differential indicated by the port number differential information.