隨著個人電腦功能不斷地提升，現今個人電腦的能力已可比擬工作站之能力。而大眾之網路頻寬隨著如非對稱數位用戶專線、纜線數據機的出現，頻寬的提升使得個人用戶也有足夠的能力分享資訊於網際網路。同儕網路 (Peer-to-Peer Network) 的架構便因此而發展，使得網路上個別用戶均能提供一己之資源，如運算能力、檔案分享、儲存空間、網路能力。而同儕網路的蓬勃應用，其流量也已成為WWW資訊散佈外的最大宗。然而同儕網路中使用者之間直接的資料傳輸，與底層的拓撲並不相符，在路由器之間造成了重複的流量，降低了頻寬的使用效率。本論文主要分析，如何讓區域網路的使用者能夠彼此優先分享檔案，從而減少頻寬的浪費，使用者也能得到快速下載的的服務品質。 同儕網路的使用者分享資源所默認聆聽的服務埠號也如同提供服務的使用者之變動性一般無法預期，無所謂公開服務埠號。本文提出藉由在區域網路中設置一台通透的網路代理伺服器，讓使用者取得修改過之Metainfo檔案，而連上內部所設置的一台BitTorrent Tracker，由內部此台Tracker告知使用者快取的位址而可以向快取下載檔案，並且區域網路中有相同檔案下載請求的使用者也能透過內部的Tracker彼此優先分享檔案，而不需連至外部網際網路的使用者索取檔案。 With the improvement of personal computers (PCs), they almost perform as well as workstations. New network technologies such as asymmetric digital subscriber line (ADSL) and cable modem make users share their resources with each other. Furthermore, the peer-to-peer network (P2P) technology allows users to share their computing power, disk spaces, and bandwidth on the overlay network. However, the P2P is usually built on the application layer of the OSI model. Thus, its messaging path is independent of real network routing. Such operation makes redundant traffic flow seriously. To alleviate the problem, we propose an approach, which forces all peers to download files from their local peers, if they are available. Further, we apply our approach to the BitTorrent, which is a very popular p2p system. We use a transparent proxy to hijack a metainfo file downloaded by a user from a Web server. Then, the original tracker of the metainfo is replaced by a new one. The user therefore connects to the local BitTorrent tracker, which directs the user to other local peers with desired files. Thus, the bandwidth consumption on WAN caused by BitTorrent will be reduced.
