An SoC-based system network protocol in consideration of network efficiency is disclosed. An MSB of a command signal containing an instruction defining information that is contained in a transfer signal transferred from an initiator to a destination via a channel or in a response signal transferred from the destination via the channel indicates that a highest priority is assigned to a transaction between the initiator and the destination in the network, when the instruction contained in the command signal corresponds to address information contained in the transfer signal and response information contained in the response signal, and indicates last data of a signal transferred between the initiator and the destination when the instruction contained in the command signal corresponds to control information contained in the transfer signal and data contained in the transfer signal and the response signal.