Patent ID: 7010595

Claim:
A method for a multi-level loopback test, wherein a loopback test device is installed between an Ethernet switch in a community and a community network system in a central office so that during the loopback test on the community network system in the central office, the loopback test device is operated by a network management system to perform the steps of: (a) in a first level of the loopback test, commanding the network management system to issue at least one special BPDU (Bridge Protocol Data Unit) packet, wherein it is determined whether a reply packet has been received from the loopback test device within a predetermined period of time; if yes and it is determined whether information contained in the reply packet shows that an I/O port of the loopback test device is normally coupled to an Ethernet switch in the community, and if the reply packet has not been received from the loopback test device within the predetermined period of time, it means that there is a disconnection between the network management system in the central office and the loopback test device; and (b) in a second level of the loopback test, the network management system in the central office issuing at least one special BPDU packet, wherein it is determined whether all of the packets sent to the I/O port from the network management system in the central office are sent back to the network management system in the central office without having any change; if yes, it means that there is a disconnection between the loopback test device and the Ethernet switch in the community or the Ethernet switch in the community is faulty, and otherwise if not all of the packets sent to the I/O port from the network management system in the central office are sent back to the network management system in the central office, it means that the loopback test device is faulty.