Patent ID: 7454517

Claim:
A computer readable storage device, storing a protocol data unit for use by a network electric device to communicate with other network devices, the protocol comprising: an application layer, a network layer, a data link layer, and a physical layer, wherein the physical layer further comprises a special protocol for providing an interface with a dependent transmission medium, and the network layer further comprises a home code control sub-layer for managing a home code for network security when accessing the dependent transmission medium, wherein an application layer protocol data unit (APDU) is transmitted between the application layer and the network layer, a network layer protocol data unit (NPDU) is transmitted between the network layer and the data link layer and between the network layer and the home code control sub-layer, a home code control sub-layer protocol data unit (HCNPDU) is transmitted between the home code control sub-layer and the data link layer, and a data frame unit is transmitted between the data link layer and the physical layer, wherein the NPDU comprises an NPDU header, the APDU and an NPDU trailer, wherein the NPDU header comprises a start of packet (SLP) field, a destination address (DA) field, a sender address (SA) field, a packet length (PL) field and a network layer control (NLC) field, wherein the NLC field comprises a service priority (SP) field, an NPDU header length (NHL) field, a protocol version (PV) field, a network layer packet type (NPT) field, a transmission counter (TC) field and a packet number (PN) field, and wherein the NPT field is set as a first code for a request packet, a second code for a successful response packet, a third code for a failed response packet, a fourth code for a notification packet, and a fifth code for an interface with the home code control sub-layer.