基于被动测量的网络故障诊断

Network Fault Analysis from Passive Measurement

A new passive method for automatic discovery and location of network failure is proposed. This method employs a passive measurement to collect information and events from network traffic, and employs a model-based reasoning system to detect and locate network faults.Measurement points are deployed in a backbone network to capture the traffic and then evaluate the Quality of Service (QoS) metrics of end-to-end IP conversations. A routing model is also established for the observed network to simulate the attributes and activities of routers and links. This routing model also deduces the routing path for each IP conversation, and thus the QoS metrics of IP conversations are mapped into the metrics of paths. With the information of shared links of overlapping paths and network tomography technique, the QoS metrics of links can also be estimated, and the poorly rated links are picked out as failure points. This method is implemented in a tool named Fault-Man, which is deployed in a campus network. Test results have shown its availability in middle-scale networks.