input output control device not shown such as a dma direct memory access controller or a channel the read out ethernet frame is managed by software such as os operating system 6 upnp processing section 61 or application software 63 the os 6 comprises a communication managing section 62 and a upnp processing section 61 the communication managing section 62 removes the ip header and the tcp transmission control protocol header from the ethernet frame and delivers the data to proper application software 63 by referring to the port number the upnp processing section 61 acquires the ip address of the electronic appliance 4 a and also information on the other electronic appliances 4 b through 4 e connected to the lan 1 more specifically it uses a piece of software that is referred to as dhcp client to acquire the ip address if it is not possible for the upnp processing section 61 to acquire the ip address by means of the dhcp client it acquires the ip address by means of an autoip feature these processing operations are carried out when the electronic appliance 4 a is driven to start operating when its own addressing is completed the upnp processing section 61 transmits a device retrieval request 10 on a multicast basis see fig4 a multicast takes place when the address of a specific group is equal to u201c 1 u201d broadcast takes place when the addresses of all groups are equal to u201c 1 u201d upon receiving the device retrieval.