The system for supporting network troubleshooting of the invention includes: storage means for periodically storing setting/configuration data and performance data of devices constituting the network based upon a schema of device IDs, interface IDs, and a respective CONFIG version number; monitoring means for monitoring the performance data of the devices by comparing the performance data with respective threshold values; identifying means for identifying the faulty device based upon the schema, when the performance data of at least one device goes beyond a respective threshold value ("faulty device"), wherein the storage means further stores the identified result for network troubleshooting. Thus, the system can estimate a factor of a change of operating condition of the network system and repair accordingly.