Downloading FTW: torrent setup for a healthy connection

Have you noticed your Internet connection getting sluggish even while your Speed-tests show no slowdown? Are your VoIP conversations breaking up and becoming unintelligible especially when torrent downloading? If your answer is yes, you might benefit from the following tips.

Internet connectivity is a sine qua non part of life for most urban consumers. Not long ago, Finland has even enshrined it as a “right” in its legislation. Other jurisdictions seem to take the opposite approach, trying to restrict access before looking at such philosophical, political and legal issues, let us deal with a simple adjustment that should make our connections better. We’ll be looking at:

1. how computers talk
2. how bittorrent works
3. what is asymmetric connectivity
4. limiting BT uplink
5. a few bittorrent websites

The first two are not all that necessary. In summary, you need to prevent bittorrent from saturating the uplink and starving the control connection for anything else you might be doing, such as a VoIP conversation. In most situations limiting should be enough but sometimes you may have to do a router upgrade.

1) computer talk

Most of us are able to connect at broadband speeds of often more than 1 Mbps (1 Byte has 8 bits, and you can’t always tell which is which making comparisons difficult). Such a connection should allow us to use it for multiple purposes, but practice seldom follows theory. For many people, downloading something makes our Internet connection unusable, and this problem does not seem to be alleviated by faster connections. To understand why, we need to understand how various applications make use of bandwidth.

Almost all activities on the ‘net that involve some exchange of information work by opening at least two connections: one where the actual information is being sent/received and a control connection, containing information about the actual transmission. On the control channel you will basically hear two computers having this kind of dialogue:

Comp1: wussup, dawg?

Comp2: nuttin’ much, just chillin’. wussup wid u?

Comp1: I need a file from you, do u mind sending it over?

Comp2: Sure, no problem. I’ll be the Server.

Comp1: Right on. That’ll make me the Client.

Comp2: I have your address as 1 Micropenis Way, correct?

Comp1: yep, make it to room “Port3424”

Comp2: I’ll send it in 3 parcels, here comes the first one!

Comp1: Got 1 and 3, but 2 got here damaged. Can you send it again?

etc

That works well and most traffic is unidirectional, but when the control connection suffers, the whole transfer suffers.

2) enter bittorrent

This unidirectional model was fine except that it did not work out well for large scale distribution of files. For instance, when Microsoft used to release updates of its OS at the same time for everybody it would routinely cause a “meltdown” of either its servers or availability issues. In this context, Bram Cohen released back in 2001 a protocol where each downloader is also an uploader. Rather than get the entire file from the central server, downloaders (through their computers or BT clients) can also negotiate the exchange of chunks of the file amongst themselves. Here’s a graphical explanation courtesy of wikipedia:

In the above animation, the colored bars beneath all of the 7 clients in the upper region above represent the file, with each color representing a individual piece of the file. After the initial pieces transfer from the seed (large system at the bottom), the pieces are individually transferred from client to client. The original seeder only needs to send out one copy of the file for all the clients to receive a copy.

BT is obviously a far more efficient way of distributing large files, such as an image of the CD or DVD necessary to install an operating system (e.g., Linux). In BT parlance, the computer coordinating the swarm and keeping track of who was / needs what is called the tracker, the downloaders are the leeches, while those who have completed their download and remain in the swarm – connected to the tracker and serving the completed file – are the seeders. The tracker does not host any data, so the traffic impact on it is small. Without enough seeders, a download will usually not complete as the probability that all the chunks are spread out is low and some owners of scarce chunks may quit in frustration before passing them on.

The beauty of BT is that the tracker (the server providing the service) does not hold the file – that is held by the seeders and chunks of it are spread all over the swarm. The tracker is supposed to “punish” those clients who have been modified to “suck up” more than they offer and generally maintain some kind of fairness in the swamp. Think of the tracker as the enforcer.

BitTorrent files are small and indexed by many websites, such as ThePirateBay.org, “the world’s most resilient tracker” and IsoHunt.com, “the most advanced” torrent search engine. Such indexers, although not doing any piracy themselves, are under constant attack by **AA – copyright cartels. If visiting such a site, make sure you do so using an anonymizing proxy, otherwise you may find yourself having to defend some mass extortion scheme disguised as a (frivolous) lawsuit.

3) asymmetry

Most home Internet connections are asymmetrical, meaning that the uplink is not the similar – more specifically, it is much slower than - the downlink. As I am writing this, my download speed is more than 30 times greater than my upload speed. This means that the uplink is far more vulnerable to saturation than my downlink. In other words, when doing multiple downloads, although your downlink may be fine, your uplink might be suffering as it is being used up by all the control connections associated with each download.

This has come to happen chiefly because most home users need to download far more than they need to upload – i.e., we suck up more info than we provide.

The aforementioned problem is particularly acute with BT, as the protocol uses the uplink not only for the control connection, but also to upload the file to other computers. Luckily, there is something you can do about it.

4) limiting BT uplink

Solving the problem for bittorrent clients is easy, as most of them allow the user to limit both the downlink and the uplink. In my clients, I usually limit the uplink only and rely on the tracker and the other clients to limit their link to me; the download link has never become saturated.

Of the following, Tribler is the most innovative, Opera is the best value, Transmission is the most “embedded” and uTorrent is the most powerful.

a) μTorrent

The mighty uTorrent (as it is usually written) is the most advanced and probably best BT client available – it’s array of options, memory footprint and stability are unmatched. To limit the bandwidth, you first go into Preferences:

Choose Bandwidth:

 

I limit my upload at 40 because my total upload is usually 50 or less. Note that you can also get this client to download only when the computer is idle (check “Stop transfer on user interaction”) or schedule downloads at night, when nobody is using the computer or the Internet in the Scheduler tab.

b) opera

Apart from being the fastest browser (especially when considering its plethora of features), Opera also comes with some unique features, such as an included BT client. When clicking a torrent link, you will be presented with this dialogue box, giving you the option to download it with Opera, save it to disk or opening it with the default BT client:

If choosing Opera to handle it, you can then click BT preferences and uncheck “automatic bandwidth restriction” to allow you to set an uplink limit:

c) transmission

This is a linux client with a nice GUI which can be accessed over the network. In the GUI, simply click the setup icon in the lower left corner:

This should be sufficient, but for a finer grain you can click Preferences:

Much like uTorrent above, Transmission allows a “turtle” mode which can be scheduled or engaged on-demand by clicking the turtle icon next to the setup icon.

d) tribler

A product of the University in Delft whose development is sponsored by the European Union, this client makes recommendations based on what you download as well as your friends. It also includes a swarm player allowing on-demand playback. To limit the uplink, just click on Settings:

There are many other BT clients available. Rather than looking at each one of them, we’ll be looking at a few BT websites.

5) sites

Apart from the aforementioned websites, which do not assess the legality of the torrents made available, a number of indexers with a focus on “decidedly legal” torrents, such as the CBC “Next Great Prime Minister” show (2008), the first TV show offered freely via BitTorrent by a public broadcaster (cbc-pm).

• ClearBits - tons of Creative Commons-licensed content; centrally-seeded (formerly LegalTorrents)
• Mininova – formerly a bad boy, now hosts documentaries from public broadcasters, HD space mission footage from NASA and user-generated animation shorts.
• The Miro Guide - content repository for the open source video player Miro, which comes with a built-in BitTorrent client
• Public Domain Torrents – out-of-copyright films in numerous formats (aka oldies or classics)
• YouTorrent – with the stated aim to index all the authorized content available on various BT sites, it is close to 100000 torrents.
• Jamendo – CC-licensed music via direct download and BitTorrent (you can easily browse it with Linux music players, such as Rhythmbox and AmaroK)
• GameUpdates – game updates, demos, patches, trailers and previews for gamers
• LegitTorrents – video, games, linux distros; also, the NIN concert DVD Another Version of the Truth and the Michael Moore film Slacker Uprising.
• LinuxTracker – all the linux ISOs you can take
• eTree - live recordings of bootleg-friendly artists in the lossless FLAC audio format.
• TorrentFreak – though not technically similar to the sites above, TF has all the latest news and features sometimes important torrents for download.

For a more in-depth look at the legislation challenges have a look at the Libertarian in Toronto; for a quick primer on copyright issues, see Edutarian.com.

Sources / More info: wiki-bittorrent, sitepoint-bt, expln-bt, cbc-pm, Opera, wiki-bt-comparison, speedtest.net

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