Communication system and communication terminal

A communication terminal connected to a communication system that executes transmission and reception of information between communication terminals through different transmission paths, comprising:

• multiple network interfacing means each connected to a different transmission path;
• a means for receiving information of multiple network interfaces each connected to a different transmission path;
• a means for creating a transmission path list that shows combinations of the multiple transmission paths to which a counterpart communication terminal is connected that are indicated by the information of the network interface received from the counterpart communication terminal, and multiple transmission paths to which multiple network interfacing means are connected;
• a means for selecting at least one combination from the transmission path list;
• a means for transmitting the probe packet to each of multiple combinations being composed of the multiple transmission path connected to the communication terminal and the multiple transmission paths connected to the counterpart communication terminal;
• a means for obtaining the state of the transmission path for each of the multiple combinations of transmission paths using the probe packet;
• a means for receiving the probe packet, communicated from the counterpart communication terminal;
• a means for measuring the interval of each arrival of the probe packet received from the counterpart communication terminal;
• a means for calculating a bottleneck physical bandwidth from the measured arrival interval and the packet size of the probe packet;
• and
• a means for reporting the bottleneck physical bandwidth as the information indicating the state of the measured transmission path to the counterpart communication terminal.

A communication method in a communication system that includes a first communication terminal and a second communication terminal each having multiple network interfaces each capable of being connected to multiple transmission paths, and the communication system executes communication between the first communication terminal and the second communication terminal using any one of the transmission paths, the method comprising the steps of:

• transmitting information on the multiple network interfaces provided in the second communication terminal;
• creating a transmission path list that shows combinations of the multiple transmission paths to which the first communication terminal is connected and the multiple transmission paths to which the second communication terminal is connected based on the information on the multiple network interfaces that the first communication terminal provides and the information on the multiple network interfaces that the second communication terminal provides;
• selecting at least one combination from the transmission path list as a route of data communication between the communication terminals;
• transmitting the information from the first communication terminal to the transmission path, by designating any one of the network interfaces that the second communication terminal that is a communication counterpart provides as a destination and by designating any one of the network interfaces that the first communication terminal provides as a transmission origin;
• transmitting the information to the second communication terminal using a transmission path connected to a network interface designated as the destination;
• transmitting a probe packet to measure the state of the transmission path from the first communication terminal;
• controlling to transmit to the probe packet to each of multiple combinations being composed of the multiple transmission paths connected to the first communication terminal and the multiple transmission paths connected to the second communication terminal;
• obtaining the state of the transmission path for each of the combinations of the multiple transmission paths using the probe packet;
• receiving the probe packet transmitted from the first communication terminal;
• measuring the interval of each arrival of the probe packet received from the first communication terminal;
• calculating a bottleneck physical bandwidth from the measured arrival interval and the packet size of the probe packet;
• and
• reporting the bottleneck physical bandwidth as the information indicating the state of the measured transmission path to the first communication terminal.