Consider distributing a file of size F to N users.

Let F be the size of a file to be distributed.

Let N be the number of users wishing to get a copy of the file.

us be the upload rate of the server's access link.

Let ui=0.02 us be the upload rate is the upload rate of user i's access link.

Let di be the download rate for user i. Assume that di is sufficiently fast that it does not become a limiting factor.

Find a value for N so that it four times as fast to use a P2P file distribution system rather than a client server system?