Inter-LAN (local area network) message transmission method and system

The invention provides an inter-LAN (local area network) message transmission method and system. In the method, a first LAN is connected with the router of another LAN through at least two Ethernet EoIP tunnels corresponding to the same port on the router by the following steps of: when a first unicast message sent by the first equipment in the first LAN to the second equipment in another LAN is received, the router of the first LAN searches for the EoIP tunnel used for sending the unicast message to the second equipment from the locally-recorded EoIP tunnels used for sending unicast messages to all equipment; if the EoIP tunnel is found, the router of the first LAN sends a first unicast message through the local EoIP tunnel connected with the LAN; otherwise, the router of the first LAN sends the first unicast message through each EoIP tunnel on the port; and after receiving a second unicast message fed back by the second equipment for the first unicast message, the router of the first LAN sends the second un