Abstract: A network device transmits broadcasting packets to other network devices in a local area network (LAN) after the network device is connected to the LAN, and receives response packets from the other network devices. The network devices determines whether the network device is a root bridge according to the response packets, and computes power consumption between the network device and each of the other network devices when the network device is the root bridge. The network device selects a path with the lowest power consumption from the network device to each of the other network devices, and builds a new spanning tree according to the selected path.

Abstract: A method for reducing authentication time of a user equipment (UE) in an Internet Protocol multimedia subsystem (IMS) network using a Femto access point (AP) establishes a secure channel between the Femto-AP and a gateway of the IMS network, performs a Femto-AP authentication with an authentication, authorization, and accounting (AAA) server of the IMS network through the secure channel, and obtains a number of virtual Internet Protocol (IP) addresses. The method further performs an UE authentication with the AAA server through the secure channel if the UE is a designated equipment in a whitelist of the Femto-AP.