Relating to a home network system and a home entertainment system, a method and an apparatus for transmitting packets in a home network system and a home entertainment system are disclosed. Additionally, a method for identifying devices to which the packets are to be transmitted and an apparatus for supporting the same are also disclosed herein. According to an embodiment, a method for transmitting a packet in a high definition base transmission (hereinafter referred to as HDBaseT) system includes the steps of receiving data from a source device in a transmission adaptor, converting the received data from the transmission adaptor to a downstream packet, in order to transmit the converted downstream packet to a receiving adaptor through an HDBaseT network, and transmitting the converted downstream packet to the receiving adaptor. At this point, the downstream packet may include a hierarchical identifier for identifying HDBaseT entities to which the downstream packet is to be transmitted.