Content delivery network system and method for network configuring

1. Field of Invention A content delivery network system is disclosed. The system comprises a communication network, a first network node for providing services for clients to access network, a second network node for managing hosts for network content providers and a third network node, wherein said third network node sets a default route and a VPN tunnel between the first and second network nodes, and provides a cache server at the bandwidth outlet of the first network node, said cache server stores a information content which has been requested and transmitted. When the client request an information content, the third network node searches the cache server. If the information content is found, the cache server provides said information content to the client directly. If the information content is not found, the cache server sends a request for catching the information content to the second network via the VPN tunnel, and transmits the information content to the client via the default route. The cache server records the data of the transmitted information content. The recorded data is provided to the second network node, so that the second network node can bill the network content provider accordingly.