A bunch of people have been pestering me about Avalanche recently, so I'll comment on it.
First of all, I'd like to clarify that Avalanche is vaporware. 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.
It's a bad idea to give much weight to simulations, especially of something so hairy as real-world internet behavior. I spent most of my talk at stanford explaining why it's difficult to benchmark, much less simulate, BitTorrent in a way which is useful. But we can look at their simulation to see if it might at least be ballpark.
Let's see, here's their simulation of 'tit-for-tat':
To simulate a tit-for-tat scenario, the simulator keeps track of the difference between uploaded blocks minus downloaded blocks from a user S (source) to a user D (destination). If the difference is larger than the pre-configured value (typically 2 when we study tit-for-tat), then the source S will not send any block to D even if there is spare upload capacity at S and spare download capacity at D.
I can't fathom how they came up with this. Researching either the source code or the documentation on the BitTorrent web site would have shown that the real choking algorithms work nothing like this. Either they just heard 'tit-for-tat' and just made this up, or they for some odd reason dredged up BitTorrent 1.0 and read the source of that. You see, BitTorrent work this way when it was nowhere near functional yet, and the first test among multiple peers (6 if my memory serves) showed that it sucks. It was promptly rewritten, way back in late 2001. This gaffe alone makes their simulation completely worthless, but it isn't the only one
