LARGE-SCALE NAT DETECTION DEVICE, APPLICATION SWITCHING DEVICE, LARGE-SCALE NAT DETECTION METHOD, AND APPLICATION SWITCHING METHOD

摘要

Large-scale NAT (LSN) can cause failures in network applications due to the limitations of LSN (number of ports and the difficulty of communications from outside). Consequently, it is extremely important for an application to check whether LSN is present on a communication channel. Although there are various methods for evaluating NAT, LSN is also NAT, and it is extremely difficult to discover LSN alone. A large-scale NAT detection device, which sends packets to a server connected via a network, determines that LSN is present on the network when an ICMP 13 (administratively prohibited) message is received from the network and a packet send/receive control unit that sends packets to the network while changing the source port number of the packets.