The invention discloses an XinIP cross-
broadcast domain data communication method, which achieves mutual communication of hosts with a same
IP address field in different networks. Three parameters of a gateway are set, i.e., a proxy
address pool, a tunnel local
IP address and a tunnel destination
IP address. A working principle of the gateway is as follows: when a destination address of a received IP data
package is matched with an address in the proxy
address pool, a new external IP header is packaged for the data
package, wherein a source IP address of the external IP header is the tunnel local IP address, and a destination IP address of the external IP header is the tunnel destination IP address; routing is then carried out; when the destination address of the received IP
package is the tunnel local IP address, and the source IP address of the received IP package is the tunnel destination IP address, local transmission is carried out after removal of the external IP header. The method has the advantages that under the premise that working principles of the communication hosts are kept unchanged, the hosts with the same IP address field in the different networks are in a same
broadcast domain, so that a traditional protocol for the same
broadcast domain can work normally.