Patent ID: 8792362

Claim:
A network device, comprising: an address move detection unit for detecting whether an address field of a first packet received by the network device is moved; a loop detection packet generation unit for transmitting a loop detection packet to other network devices in response to the address move detection unit detecting that the address field of the first packet is moved; a packet parser unit for parsing a second packet received by the network device to extract information; a loop determination unit coupled to the packet parser unit for determining whether the second packet matches the loop detection packet based on the information so as to determine whether any loop exists involving the network device; and an operation state unit coupled to the address move detection unit for recording an operation state of the network device, wherein the operation state comprises at least a loop state, wherein with the operation state unit in the loop state: the loop determination unit checks whether a loop exists; and the network device emits a warning signal if the loop exists.