A network system includes a device management (DM) server and a Machine to Machine (M2M) gateway coupled to the DM server and to a plurality of sensor devices in a sensor network. The DM server is configured to send a DM command. The M2M gateway is configured to: after receiving the DM command, access a topology tree that includes first and second management object (MO) nodes, wherein the first MO node includes an identification and a type of the sensor network and the second MO node describes a characteristic of each of the plurality of sensor devices and a connection relationship of the plurality of sensor devices; according to address information within the DM command, locate at least one of the first and second MO nodes; retrieve information from the located at least one of the first and second MO nodes; and send the retrieved information to the DM server.