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Hylton Jolliffe writes "I wanted to alert you to an article by research Marc Eisenstadt that digs deep into BitTorrent, its potential and limitations and its implications for podcasting, filesharing and more."
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I grabbed BT for Win2000 and installed it in about 7 minutes, then I hit the torrent link for Knoppix. I was downloading the ISO at around 36KBps (about the limit of my DSL connection).
Since I was heading to bed while it downloaded, I left BT up that night and the next day while I was at work to help other people out.
I had seen BT as a place to snag nothing but rips of movies, and I've stayed away. The legal-usese BT community needs to do a better job of promoting the positive and allowable uses of BT and P2P sharing tools. They have a way to negative stigma right now.
GET REAL
January 11, 2005
BitTorrent, eXeem, Meta-Torrent, Podcasting: "What? So What?"
Posted by Marc Eisenstadt
SUMMARY: The index that facilitates the sharing of files on a large scale is also the Achilles heel of peer-to-peer file-sharing, because it is vulnerable to litigation and closure. So what happens if the index is itself distributed? I try to get my head around the latest in peer-to-peer file sharing, and explain a bit about what I've learned, including the fact that BitTorrent's power rests in its 'swarm' distribution model, but not necessarily in your end-user download speed. What has this got to do with podcasting? (Answer: invisible P2P plumbing helps the podcasting wheel go round).
[Warning: lengthy article follows].
First, some history
(skip ahead to the next section if you're already bored with the Napster, Gnutella, KaZaa, and BitTorrent saga).
Napster opened our eyes to the power of distributed file sharing on a massive scale. But it was closed down by lawsuits to stop it from listing copyrighted works for which the owners would naturally have preferred to collect royalties (there are thousands of commentaries on the pros and cons of such royalties, but that's not the focus of this posting). Successive generations of tools such as Gnutella, KaZaa, and now BitTorrent have created their own buzz, their own massive followings, their own headaches, and their own solutions to others' headaches. Here's my rundown of the 'big ideas' (and the people behind them):
Napster (Shawn Fanning): This was the Mother of big-time peer-to-peer (P2P) file transfers, i.e. my computer directly to yours, with a central server to maintain lists of who had what in order to initiate the transactions. It had a pretty decent user interface, plus the rapid growth, novelty, excitement and publicity that ensured plenty of good content. Those central server lists, leading to mass free trading of copyrighted material, also led it to be shut down.
Gnutella (Justin Frankel and Tom Pepper, creators of WinAmp): This was an open-source protocol that linked autonomous 'nodes' (users of the network) to other nodes, thereby eliminating the need for a central server list. Searching reliability varies, however, because it is subject to outages according to the connection/disconnection of individual users along the way.
KaZaa (Niklas Zennstrom and Janus Friis, who later created Skype): This technology built on a proprietary protocol called 'FastTrack', conceptually an extension to Gnutella, that deployed distributed 'supernode' search indices whose IP addresses were built in to the software, and which avoided the problems of (i) Napster's centralized lists and (ii) Gnutella's over-distributed nodes suffering outages and weakening the search. The prevalence of built-in 'adware' and the distribution of 'junk files' that masqueraded as originals were two of the weaknesses of the (still) wildly popular KaZaa.
BitTorrent (Bram Cohen): This was the next 'creative leap' in the P2P world, based on the following insight: distributing large files in fragments among large numbers of users, and requiring every downloader to be a partial uploader (of these fragments), enables the 'best of breed' of swarming behaviour -- as a file becomes more popular, so it becomes easier to download, rather than harder (as is the case with traditional file distribution)! A good overview explanation and a helpful analogy are provided in this excerpt from Brian Dessent's BitTorrent FAQ and Guide:
BitTorrent is a protocol designed for transferring files. It is peer-to-peer in nature, as users connect to each other directly to send and receive portions of the file. However, there is a central server (called a tracker) which coordinates the action of all such peers. The tracker only manages connections, it does not have any knowledge of the contents of the files being distributed, and therefore a large number of users can be supported with relatively limited tracker bandwidth. The key philosophy
So BitTorrent is just about spreading the distribution load across multiple peers and can't speed up my physical connection to the internet.
That's why I click on every banner I see that says "click here to increase your download speed". I think of them as the little speed boost arrows you could drive over in Excitebike.
--
This is a joke. You have been joked with.
BitTorrent requires tracker sites to handle all the partial-fragment-negotiation (think of the madness of the floor of the New York Stock Exchange, and you get an idea of the cool juggling that a tracker has to do).
If he knew anything about BT, he would know that the tracker only introduces peers to each other. The tracker only knows which peers are finished and which aren't. Each peer then manages it's own "fragment-negotiation" which is really just downloading the rarest pieces from it's own point of view. There isn't any negotiation at all, really.
burris
HERE! is a torrent of torrents from the former Suprnova! Download and spread the word!
Then, when a low volume, private site suddenly gets its 15 minutes of fame by being mentioned on Slashdot (or some other well-read news broadcast), it would automatically enlist the horde of new requesting sites to help distribute its content. The rest of the time, both before and after the flash mobbing period, it would just serve its own pages itself in the current manner.
Since it is hard to predict which sites will be "discovered", it would be necessary for all standard servers and browsers support the http protocol extension, so this can't happen without a lot of coordinated work, I'm afraid. The protocol would have to be extended, web servers modified (Apache would e adaquate for a start), browsers modified (Mozilla/Firefox would be adequate for a start). When server was becoming overloaded it woud start by discarding requests from browsers that did not support the protocol, so that it can build up the initial seeding of helper sites. As long as there was more demand than available helpers, these old incapable browsers would continue to get ignored. Once a large enough group of capable helpers was built up to fully support itself, the group could start accepting requests from incapable browsers. That would provide incentive to upgrade older browsers.