Can Peer-to-Peer live streaming systems coexist with free riders?

Peer-to-Peer live streaming systems help content providers and distributors drastically reduce bandwidth costs by sharing costs among peers. Researchers have dedicated significant effort developing techniques to discourage or exclude uncooperative peers from peer-to-peer systems. However, users are often unable to cooperate, e.g., users using a mobile device with limited, costly bandwidth. We study the impact of uncooperative peers on video discontinuity and latency using PlanetLab. We find that simple mechanisms, like forwarding video data requests to cooperative peers instead of wasting effort sending requests to uncooperative peers, allows peer-to-peer live streaming to serve 50% of uncooperative peers without performance degradation. We argue that denying service to uncooperative peers may not be the best long-term approach; our findings suggest that peer-to-peer live streaming can support uncooperative peers.