As a result of widespread of peer-to-peer (P2P) file sharing applications, it is a serious problem that inter-domain traffic between Internet Service Provider (ISP) networks increases. In this paper, we present a novel inter-domain traffic flow model focusing on the presence of a passive peer, and proposes a new P2P traffic control method based on the model. This method uses a filter considering P2P flow characteristics and can be applied to the P2P networks whose protocol is closed. We also evaluate both validity and effectiveness of our proposals by performing more than 20 days experiments using real P2P network environment. The results prove that our model is reasonable enough and the proposed method is promising for decreasing inter-domainP2P traffic.