The Impact of Network Address Translation on Peer-to-Peer Live Video Streaming Systems

Video streaming over the Internet can be very dicult under the traditional client-server model. Peer-to-peer (P2P) systems, in which each participating peer contributes its upload bandwidth to other peers while it downloads data, have been successful in le-sharing applications, and they appear to be promising in delivering video contents, too. However, the existence of network address translation (NAT) is always considered as a challenge to peer-to-peer systems. NAT has been a practical solution to the Internet Protocol version 4 (IPv4) address exhaustion problem, as it reduces the usage of IP addresses by allowing multiple private hosts to share a single public IP address, but NAT can degrade the performance of a peer-to-peer system as it limits the direction of connectivity. Measurement studies show that a considerable fraction of peer-to-peer video streaming system users are behind NAT devices, and that their uplink bandwidth is not well utilized, but the literature lacks a quantitative analysis of the impact of NAT on the performance of P2P video streaming systems. In this thesis, an extensible analytical model is built to capture the performance for P2