This paper gives a comparative study on multilayer file sharing mechanisms in Peer-to-Peer (P2P) systems. Based on a well-known P2P system named Gnutella, two system architectures, 1-layer and 2-layer Ngnu architectures are proposed in order to reduce network traffic and to gain better scalability. These architectures can be applied to large-scale systems, such as e-government, e-office and e-library, which need an efficient file-sharing mechanism. To examine the efficiency and effectiveness of the proposed methods, a number of simulations are made with respect to three factors: time-to-live?s (TTLs), the number of nodes and the number of queries. To compare these systems, the number of messages and the mean query hit are measured and compared with the original flat Gnutella system.