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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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.

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.

Actually reasonable requirement, useful feature

[billstewart]

Some environments, like the Gnutella/Napster/Freenet things, have communities that hang around connected for a long time even if they're not downloading anything. But others, like distributing a new release of RedHat/Debian/Mandrake CDs, or even just Mozilla, have a lot of users who want to show up, download stuff, and leave. This feature makes it possible for them to be a temporary community providing services to each other without requiring longterm committment. If you download a CD using BitTorrent, you're useful for 95-99% of the time you're on line, rather than being consumer-only for the first 100% of the download time and having to hang around for another 100% of the time to be any use to anybody, so the community scales much more cleanly even if the first thing you want to do after downloading the latest Linux release is install it. (Software's a much different usage pattern than music here.)

Additionally, it makes it very efficient for the first set of people who are downloading the file. Instead of having to download the whole thing from one source, which is probably overloaded, you're able to download pieces from lots of different people. The server takes advantage of this - instead of giving Alice chunks 1, 2, 3, ..N in order, and giving Bob the same things, it spreads around the load, so Alice is downloading chunk 1 while Bob downloads chunk 2, and when they're done, Alice starts downloading Chunk 3 from the server and Chunk 2 from Bob, and other chunks from Dave, Eve, and Freddie if they've gotten them.

This also reduces the latency required for later people in the process to get their material - instead of waiting for the entire 600MB CD to be copied N times in a row, the downloading gets pipelined.