This paper proposes a network system reliability analysis method based on service. The significance of the network services becomes increasingly prominent in many fields like communication and aviation industry. More and more services depend on network transmission. Thus, the dependability and the reliability of network system are paid more and more attention. The reliability of network is related to several factors, such as hardware equipment, software services, human factors and so on. Most previous papers pay more attention on the hardware equipment factors than the others. The reliability of network is measured by if the equipment is normal running. Sometimes the hardware equipment is in normal operation, but some users may think that the network service is unavailable due to the network congestion, software errors or man-made mistakes which have no effect on the calculation of the reliability. There is a gap between the state of service execution in terms of reliability and what the network reliability data suggests. This paper attempts to propose a network service reliability analysis method based on service to bridge the gap. The paper satisfies these needs in the following ways:(1) we analyses various factors affecting reliability of the network system; (2) we establish the reliability block diagram of service operating process and calculate the reliability of the equipment by the diagram (3) we analyze a case utilizing the model in (2). This method will not overestimate the availability of network system. It enhances the previous study by utilizing the analysis based on service. With this method the gap between the service experience of users in term of reliability and the result reliability of the method will be bridged.
