Finally Real P2P With Brains

dfelznic writes: "The mp3 archives of CodeCon are now availble, which is news in itself. But what makes this real interesting is that they are being distributed by BitTorrent. BitTorrent allows users to download a file from multiple different people. Instead of everyone nailing one server, users get the file from other users. Furthurnet uses a similar technology to distribute legal bootlegs of concerts. The archive is available at the BitTorrent demo downloads page. As soon as I started downloading (cable modem) at around 300k I got a request for the file and began uploading at 40k. This could be the answer to the slashdot effect;) Now, who is going to be the first to complain about the use of mp3s instead of oggs?"

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Re:Nice.

[shankark]

That's true. But I think a workaround for this would be to have md5 signatures computed for each of these parts and verify them before they are downloaded. I'm not sure if this isn't being done by others already.

And this is new?

[Edgewize]

Could someone explain how this is different from FastTrack (Kazaa), eDonkey, or the more reputable Swarmcast?

Peer broadcasting is hardly something to write /. about, I'd say.

Re:And this is new?

[PureFiction]

Sure. Fast Track is decentralized file sharing network where there is no guarantee that what you ask for is what you get. They may be codecon mp3's, they may be nasty midget porn incognito.

eDonkey likewise is more of a filesharing (aka, keyword search, then dowload hits) method.

Swarmcast is the closest relative to BitTorrent, but BitTorrent avoids the FEC encoding and cryptographically secure block verification in favor of a more centrally controlled broker that uses multi source downloading at various offsets to accomplish the same task.

In short, BitTorrent is a distribution system where a central server provides content, and peers requesting that content join a mulitsource downloading group where they also share offsets of data with each other (preferably) and download from the central server when necessary.

This isnt file sharing (really), this is content distribution in a fast and effective manner using peer networking concepts.

It is NOT a p2p Network people!

[Com2Kid]

It is a browser plugin (IE) that creates mini distributed networks based around a website.

So say you start downloading the latest Counterstrike patch from some server. Well you know how servers giving out the CS patch get filled up quickly.

Well if the users were running this program (plugins to IE, no restart neccisary, look if there is a {browser here} version yourself!) then when they started downloading somebody ELSE could start downloading FROM them.

No file synch issues (same file, same source) the server just re-directs future downloaders to current downloads and has the original downloaders forward the files along.

BitTorrent

[Eloquence]

I'm sure Bram will notice his server being slashdotted soon enough, but let me say a few words in defense of BT anyway. What makes BT different from Morpheus and BearShare is that files are sent by users to each other, while they are still downloading. This way, the downloaders themselves act as backup. It's not simple multi-source downloading, but targeted towards content-providers who want to reduce load on a central server. In its advantages and disadvantages it's similar to Multicast. Good for high load for specific files at specific times. Kernel.org should use it.

eDonkey has the same feature (with some differences in the publishing process), but is really an application of its own, very file sharing oriented, closed-source and banner-supported. Not exactly what a content provider would want users to download before they can access his files. Still, ed2k has the advantage of a large user base, and also supports ed2k:// URIs that can be used on webpages.

SwarmCast is interesting, but the company behind it mostly died, and now it is somewhat in limbo. Its Java base has made it problematic as a desktop application. The only real alternative to BT is Mojo Nation, which is currently being reworked as "MNet".

If you want to know what CodeCon is all about, check the Feature box on infoAnarchy, we had some detailed coverage.

What about Gnunet?

[Anonymous Coward]

I'm very surprised at the little ammount of attention that GNUnet has gotten in the P2P arena. GNUnet is anonymous, distributed, encrypted, reputation based, has accounting, allows for distributed queries, and uses dynamic routing. While GNUnet is still beta software, I think it's a great anti-censorship tool. What all this means in non-buzzword speak, is that you have a tool that combines a lot of the great qualities from other similar networks (FreeNet, mojo nation, etc) and doesn't have all of the short comings. Give it a shot.

multiple identical different same distinct

[Dr. Awktagon]

BitTorrent allows users to download a file from multiple different people.

Or if you're downloading the latest boy band single: multiple identical people.

I'd like to hear peoples's experiences

[Anonymous Coward]

I'm Bram Cohen, the author of BitTorrent. This little slashdotting seems to be going well so far from my end (over 40 downloads currently, and still going smoothly) but I'd like to hear about peoples's experiences doing the download. Here are some questions -

• Are you getting pauses where no download is happening? If you are, please be patient, it should kick up again (or start in the first place) after a while.
  
• Are you behind NAT? People behind NAT may be getting worse performance, it's a complicated issue.
  
• How's your upload/download ratio? There are enough people now that you may see the phenomenon of getting about the same download rate as your upload rate - Cutting off your uploads wouldn't help with this, your peers would just get pissed off at you and stop uploading (I'm not kidding, it has tit-for-tat leech resistance.)
  
• Did you run into any technical glitches? It's still fairly young software, so there may be a few little things to iron out.
  

So far, this looks like it's going pretty well. Any and all feedback is much appreciated, and will hopefully help make BitTorrent an even better product. Please mail me about your experiences.

"chaining" is DIFFERENT than "swarming"

[rubybroom]

I'm not completely versed in morpheus/kazaa/bearshare/whatever, but I understand they allow you to download a file from more than one other person simultaneously, known as "swarming" the download (btw, this is called "anteloping" on furthurnet). It is my further understanding that you can only do this from people who have the *complete* file.

What bitTorrent (I think) and furthurnet (I know) are doing is different than this. If 5 people are downloading a file from the one person who is sharing it, those 5 people can be the beginning of 5 chains of people, relaying each packet down the chain as they get it, regardless of whether or not anyone has the complete file.

Furthurnet uses a protocol called PCP (Packet Chain Protocol) to do this, and it automatically arranges the chains so that those with faster upload speeds are toward the top, with the dialup users toward the bottom.

If the main host goes offline, even if no one on the chain has the entire file, everyone on the chain can still continue downloading everything that the topmost person on the chain has already saved.

A good example: say a dialup user has large file that is in high demand. A T1 user comes along and spends a long time downloading it off of the dialup users horrible upload speed, and gets about 80% of it before anyone else comes to download. Then you show up with your cable connection and instead of being at the mercy of the upload speed of the dialup guy, you have access to 80% of the file from the plentiful upload speed from the T1 guy. And of course Furthur knows to hook you up to the fastest open slot available when you come along.

The result of this is that the underlying host and network shape becomes transparent, and you just see a list of shows to download, you start downloading one, and all this stuff happens in the background. The longer everyone stays connected to the network, the more efficient it comes because it has more time to structure it with the faster folks in the "middle", and the slower ones on the "outside".

Over at furthurnet, the current record is having 71 people on a downloading chain. Combine PCP with the Anteloping and you can have some serious improvement over "dumb" p2p.

I wont even go into the benefits of the md5 checking furthur does...

Lossless - big files - Bittorrent helps a lot

[billstewart]

If you're shipping around small files, like MP3s, there are lots of transfer systems that can do the job. But the Lossless Compression movement for music means that a concert tape is typically a few hundred megabytes large, maybe 1/3 the size of the uncompressed original, so it takes much longer to download, just as ISOs for Linux distributions are large. In that environment, you can't always depend on connections being up for a long enough time, so you need to be able to download parts of files, and swarming systems like BitTorrent help a lot.