From the end of 1970S, the Local Area Network(LAN) has been considered as the new technology of computer networks. LANs are recently being installed in campus, offices, factories, and other areas. As users in LANs gradually want to communicate with others and use the resources located at remote network, the interconnection of LANs is reached to maturity. In this thesis, the structure of the interconnected LAN should be the "hierarchical fashion". The hierarchy gives the economy of scale, the modularity, the large amount of resources to the lowest level machine/user, etc. We define the characteristics of Hierarchical LAN (HLAN) and classify the already existed LANs by hierarchy, which attempts to give the clear understanding of HLAN. Because the interprocess communication is not supported between processes residing on different networks, we propose the model which makes it possible: the Net IPC Server.