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Bram Cohen Lambastes Avalanche
June 21, 2005
Thomas Mennecke
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Late last week, there was a flurry of media attention surrounding Avalanche. Avalanche was labeled as Microsoft's answer to BitTorrent, prompting such headlines as "Microsoft launches Avalanche, rivaling BitTorrent" and "Microsoft Develops BitTorrent Clone." While the mainstream media heralded this as the second coming of Jesus, it turns out that no such application even exists.

"First of all, I'd like to clarify that Avalanche is vaporware," Bram Cohen writes in his weblog. "It isn't a product which you can use or test with, it's a bunch of proposed algorithms. There isn't even a fleshed out network protocol. The 'experiments' they've done are simulations."

On the surface, Avalanche appeared promising. One of the more frustrating aspects of BitTorrent is that many times, file transfers slow down to a crawl towards the end. This happens when the sources of information begin to dry up. Avalanche proposed a type of "Par file" error correcting system. During BitTorrent transfers, a file is broken up into many segments. Avalanche proposed that each segment of a file will be encoded with an error correcting code. Once enough of these codes combined, the file will automatically finish creating itself. Seems like a novel idea, right?

However, Bram Cohen had already covered the topic in November of 2004, in which he responds to repeated requests for the feature.

"It isn't done because, quite simply, it wouldn't help."

Bram goes more into technical detail by presenting three possible benefits, with corresponding rebuttals.

Bram goes on to criticize Avalanches implementation of error correcting.

"The really big unfixable problem with error correction is that peers can't verify data with a secure hash before they pass it on to other peers. As a result, it's quite straightforward for a malicious peer to poison an entire swarm just by uploading a little bit of data. The Avalanche paper conveniently doesn't mention that problem."

Bram continued to rip into the very heart of Avalanche, dismantling most of their proposals. He did however, credit the work on from a more literary point of view.

"As you've probably figured out by now, I think that paper is complete garbage. Unfortunately it's actually one of the better academic papers on BitTorrent, because it makes some attempt, however feeble, to do an apples to apples comparison."

This story is filed in these Slyck News categories
P2P Clients :: Other Clients
BitTorrent :: BitTorrent Inc.
File-Sharing/P2P Related :: Software

Bram Cohen's journal.

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