Nowadays each network management system (NMS) adopts different methods for collecting network information and different data structures. This makes NMS cooperation difficult, especially in multi-AS wide area network management. The current goal of the KANVAS (Knowledge base system in wide Area Networks with general Versatility, Availability and Scalability) project is to realize wide area network management by constructing a knowledge base system in networks. This paper discusses construction of a knowledge base system in a single AS (Autonomous System) towards the future wide area network management. This paper also shows the design and implementation of the knowledge base system that collects network configuration information from OSPF and SNMP, and stores it as instances of our proposed network ontology called Bonsai. Additionally, a prototype application that accesses the stored knowledge was implemented. The evaluation of basic performance and scalability of the system was carried out using a real AS topology and synthetic topologies and it was made sure that the prototype application works correctly. As a result, this paper shows that feasibility of the future wide area network management that adopts the knowledge base system.