Peer-to-Peer File Distribution

A method of distributing files over a network in which individual computers, called peers, share files directly with each other without the need for a centralised server.

P2P distribution has the advantage of scaling better with an increasing number of peers on a network compared to Client-Server Architecture.

Stats

The distribution time $D_{P2P}$ to transmit one copy of a file of size $F$ to $N$ peers that each have the download speed $d_i$ and upload speed $u_i$, where the initial distribution happens form a server with upload speed $u_s$, is

D_{P2P} = \max \left\\{ \frac{F}{u_s}, \frac{F}{d_{\text{min}}}, \frac{NF}{u_s + \sum_{i=1}^N u_i} \right\\}

where $$\begin{gathered} d_{\text{min}}=\min \\ {d}_1,d_2,\dots ,d_N \end{gathered}$$.

Implementations

• BitTorrent.