Approaches for practical BitTorrent traffic control

As practical ways to control BitTorrent traffic, we examine two basic approaches that exploit existing features of BitTorrent instead of modifying BitTorrent system. Based on PEX that allows BitTorrent clients to exchange their neighboring peer information directly, we propose topology-aware PEX, tPEX to inject some local peers to each local peer in the target network domain for the traffic localization. We also try to redirect the unavoidable inter-domain traffic from the transit links to the peering links by affecting tit-for-tat (TFT) strategy through the delay insertion (indirectly guided TFT, gTFT). Through simulations, we show that tPEX increases the intra-domain traffic volume by up to 316% and reduces the charging volume by up to 32.2% and the download completion time by up to 43.3%. gTFT reduces the inter-domain traffic volume of the transit links by up to 11.1% and increases the inter-domain traffic volume of the peering links by 9.2%. gTFT reduces the charging volume by up to 9.7%. Even though gTFT does not much affect the average download completion time, gTFT increases the performance difference among peers by up to 28.6% by adding the artificial delay selectively. tPEX+gTFT shows almost similar performance to that of tPEX, since gTFT loses its ability to redirect the inter-domain traffic once tPEX is applied. Above results show that tPEX can be the practical win-win approach to satisfy both ISP and users.