LAN-to-LAN communication method, and LAN-to-LAN connecting unit

摘要

A LAN-to-LAN connecting unit sends a node-status confirmation packet PKTC to LAN terminals under its command to confirm the status of each terminal. Upon receiving the confirmation packet, a normal terminal sends a response packet PKTR back to the LAN-to-LAN connecting unit. However, a LAN terminal incapable of receiving data because of a pulled cable or some other problem cannot send back the response packet. The LAN-to-LAN connecting unit identifies and stores information indicating whether a LAN terminal is capable or incapable of reception depending upon whether the response packet is received. In a case where an incoming call has been terminated at a prescribed LAN terminal and this terminal is capable of reception, the LAN-to-LAN connecting unit receives the data sent from the other party's LAN terminal and transmits this data to the LAN. In a case where the prescribed LAN terminal is incapable of reception, the connecting unit disconnects the line immediately. If a transfer destination has been registered to correspond to a terminal that is incapable of reception, received data is transferred to the transfer destination.