Freeriding not (always) considered harmful

Measurements of real-world peer-to-peer systems have shown that up to 80% of the peers are so-called free-riders; they do not contribute any resources to the system but use resources from other peers. Free-riding is commonly considered a problem, yet no quantitative evaluation about its real effects has been performed. In this paper, we present a quantitative evaluation of the effects of free-riding on download times and service loads in a peer-to-peer content distribution system. Our results show that allowing free-riding in many cases significantly improves overall system performance. The improvement is more pronounced in realistic, heterogeneous environments.