  P2P systems provide a scalable solution for distributing large files in a
network. The file is split into many chunks, and peers contact other peers to
collect missing chunks to eventually complete the entire file. The so-called
`rare chunk' phenomenon, where a single chunk becomes rare and prevents peers
from completing the file, is a threat to the stability of such systems.
Practical systems such as BitTorrent overcome this issue by requiring a global
search for the rare chunk, which necessitates a centralized mechanism. We
demonstrate a new system based on an approximate rare-chunk rule, allowing for
completely distributed file sharing while retaining scalability and stability.
We assume non-altruistic peers and the seed is required to make only a minimal
contribution.
