BitTorrent

Myeah, so, I was completely bored and I had to write a paper for my English class regarding a tech subject so I chose BitTorrent.

Let me just state this from the start, BitTorrent is just smart. Brilliant even. Why’s that? Unlike other P2P networks, BitTorrent strives for efficiency.

How does it work?
You need:
1. client software
2. .torrent file
3. tracker server
4. bandwidth

1. Client software. There’s a plentitude of [good] BitTorrent clients and the list just gets bigger and better. One of my favorites is µTorrent (http://www.utorrent.com/). Others really worth mentioning are Azureus (http://azureus.sourceforge.net/) and ABC (http://pingpong-abc.sourceforge.net/).

2. .torrent file
To be able to download a file via BitTorrent you need to have this small description file which holds the name of the original file, file size and the tracker address for the file.

3. Tracker server
The tracker server is the central source of information for any client. It accounts a list of active users which have the file or fragments of the file you are downloading and it also has a statistic of the distribution of fragments in the swarm.

The swarm is actually a small ad-hoc P2P network which is created when you are downloading a file — you are automatically connected to the other users which download (or have downloaded the file). In order to use most efficiently the bandwidth the software tries to download the fragments of the file which are least popular. This way the distribution can be evened out. If a user who has 3 file fragments which are the least popular would exit the swarm (i.e. close the client) then all the others would have to wait for those fragments until he comes back. You could end up with a 4.37 GB file which is missing 12 MB of data because there are no users with those blocks available. That’s why the netowork tries to replicate and distribute the blocks as evenly as possible to avoid bottlenecks and incomplete files.

4. Lots of bandwidth
Once you get everything up and running everything will be working waaaay faster and easier than you ever imagined.

What thrills me is the way the best network connection is chosen for each of the peers. Also, the way it tries to keep the file inside the swarm is admirable. BitTorrent is really something.