If you have read the first two sections of this series, you will have read about what BitTorrent is and how to use it. You would have also read about how BitTorrent works. What follows now is a real-world example of how BitTorrent can be used in a corporate environment.
We go back to a previous example about a company which has a 200 person sales force in the field. They are needing to distribute 50 GB worth of video files for the sales people to use to promote the company's product.
This 50 GB file originally took about 7 hours to download for each sales person. This generous speed example works when assuming that only one team member at a time is downloading it. At some point, the number of copies of the videos being downloaded at one time will effect how quickly the file can be received by any team member. For example, if the bandwidth of the people in the field is 10 Mbps and the server can only serve out 50 Mbps, then once more than 5 people connect, the rate of transfer slows down for everyone.
Remember that we have 200 team members who need this file. If only 5 at a time can get this file at full speed, then it would take 40 blocks 7 hours time periods for everyone to get their copy. That would take 280 hours, or almost 12 days!
With the team using BitTorrent which allows all of the members to both download and upload the information at the same time, the sales force could realistically all have a copy of the videos in just a bit longer than it takes for one file transfer. In a worst-case scenario, it may take 10 times longer than for 1 person to get the file (it won't take near that long). That is still only 1/4 the time it would have taken by using traditional file transfer methods. Unlike traditional file transfers, with BitTorrent, the more people you have trying to get the file, the faster the distribution will go (up to a point). Traditional file transfer protocols mean the more people wanting the file, the slower it will be for everyone.
Here is another amazing thought about how BitTorrent works. If 5 of the downloaders are sitting on the same network (and therefore they have a much higher connection speed between one another), as soon as one of them gets that section of the file, it gets propagated to the other 4 people in the network at a much faster speed than them grabbing that section off the original server individually.
Can you start to get an understanding of how BitTorrent can be a huge help in quickly transferring large files? The beauty is that, with the exception of the very first copy, no one person/machine is waiting on any other one person/machine to get the file. If my computer can serve out the few bits of information it has to anyone requesting it, that frees up the main server to give me the next chunk that I need. This is the tracker, seed and peer relationship working that I explained in the last article.
Just a couple of more things to make you think about the power of BitTorrent. If I needed to download 5 different 50 GB files from different servers, the BitTorrent client I am using will be able to handle all of them at one time. They will download while I am not even paying attention to them. I can even choose to download them at a slower rate so that it doesn't use up all of my bandwidth while I am trying to do other web browsing.
The way network traffic works everything is delivered in packets. While I don't pretend to understand all of this, individual small packets can be transferred much faster than large groups of packets that make up a file. When downloading a large file from one server to one computer, you may only get about 1/2 of the advertised download speed of your Internet connection. However, transferring packets through the BitTorrent protocol, it is common to get the full speed of your possible allotted bandwidth.
When a new sales person joins the team and now needs to grab the videos, she is not limited to getting the file off the one central server. She can get them from any of the 200 other computers within the sales force. She may happen to be in an office where 6 other machines are seeds (meaning they have the complete 50 GB package). They have the files ready to give her. She will quickly transfer the file over to her machine at a rate far faster than downloading through the Internet. The tracker will inform her that the fastest connection to download the files are the other computers sitting in the same office. This is don automatically, so the user never even knows whether the file came from across the room, or across the world.
Unfortunately, the new sales person was only able to stay at the office for 12 minutes. She only got 75% of the file. But on her lunch break at the coffee shop, as soon as she connects to the Internet she will start transferring the rest of the file. When the transfer is done, she will have a complete copy of the videos at only a portion of the time it would have taken if she had to get it all from a central server.
If she had to get the file from one server, then, depending on the file transfer protocol she was using, she may need to get the file in one sitting. Some protocols do not allow you to disconnect from the download and resume it later. She would have to make sure her Internet connection was solid for the 7 hours of transfer time. But with BitTorrent that is not an issue. Stopping and resuming a file transfer is all part of the way BitTorrent works.
This is just one of the many examples of the way BitTorrent can be used in a corporation. There are also legitimate individual uses for BitTorrent.
While there are people doing illegal things using BitTorrent, the technology is quite amazing and nothing to be afraid of.