FIRST RELAY SERVER AND SECOND RELAY SERVER

摘要

An object is to provide a communication system excellent in flexibility and expandability in the event of constructing a communication system in which communication terminals communicate with each other through a WAN. A relay server 12 and a relay server 23 share relay group information and relay server information. In the relay group information, a network address of a LAN 1 that performs routing control via the relay server 12 and a network address of a LAN 2 that performs routing control via the relay server 23 are registered. The relay servers 12 and 23 establish a routing session via a WAN 3. When a communication terminal connected to the LAN 1 sends out a communication packet in which an IP address of a communication terminal connected to the LAN 2 is designated, the communication packet is routed through the routing session between the relay servers 12 and 23 while being encapsulated.