Research On Fault Detection Method Of Network Cable Based On Signals In The Network System

Local area network, an important part of internet, is not only the most active branch of computer network, but also the base of wide area network, and the communication quality and daily maintenance and management of which should not be ignored. As the network cables are put into the wall, pipes and underground, when the network cables break down, it will destroy the buildings to find the fault directly. And finishing the fault detecting work may consume a large amount of human resources and materials, and take several hours even more than dozens of hours, people’s study, work, and research will suffer larger economic losses. Fault diagnosis of local area network has been a focus of concern always, and convenient, cost-effective and highly efficient fault detecting is an indispensible guarantee for the run of communications network. Based on signals from the network itself, this dissertation studied the character of the signal, and provided an in-depth discussion on network cables fault detecting, the main studies include the following three aspects:1、 We propose the method of network cable fault detecting based on the signals from the network itself theoretically, and prove the existence of these signals combining with the knowledge of computer network.2、The application of this method in the fault detecting of UTP is proved experimentally. Through replacing the external signal of the traditional reflectometry with the auto-negotiation signal in the network system, we could realize the network fault breakpoints detecting by correlation method. Different fault points of the unshielded twisted pair are located experimentally utilizing the auto-negotiation signal of RG-S2628G switch, and the relative standard deviation of fault location is0.29%. The experiment results also show that the value and location of impedance mismatching and the fault type can be determined. Our method provides a new idea for network fault detecting.3、 The application of this method in the fault detecting of optical fiber is proved experimentally. Through replacing the external signal of the traditional OTDR with the signals from the network system itself, we could realize the optical fiber fault breakpoints detecting by correlation method. Using the light from the optical transmitter and receiver, we measure the faultbreaks in the optical fiber, and analyse the accuracy, resolution and dynamic range of this method.4、We summarize our discoveries and discuss the possible research directions in the future.