FastTrack

FastTrack is a protocol similar to the eDonkey2000 protocol, but it cannot download from users who do not have the complete file. The protocol was used by KaZaa and Morpheus, later the Sharman Networks bought rights and monopolised FastTrack protocol.

With version 2-4-1 MLdonkey introduced FastTrack support. With version 2.5 (stable) MLdonkey FT-support is distributed with the official binaries.

Mldonkey also supports OpenFastTrack which is an non-commercial clone of FastTrack. Open FastTrack can be characterised by highly available well connected servers hosting high quality files such as Ogg Vorbis.

there's some encryption in fasttrack please explain

The Fasttrack plugin will not work on your computer, since the encryption algorithm does not work correctly. You can try to solve this problem by hacking the C files in

  mldonkey/src/networks/fasttrack/*.c