On Wed, Oct 04, 2006 at 02:12:23PM -0400, Tim McCormack wrote: > Anybody know of research that has been done on the optimal ratio of node > types in a Tor-type OR network? Assuming all traffic goes through three hops (and for the most part it does; the four-hop cases are a bit weirder and a lot less frequent) then, to a first approximation, we want at least 1/3 of capacity in exit nodes. (That's capacity, btw, not number. 2 exit nodes that do 10kbps are not really much better from a capacity POV than 1 exit node that does 20kbps.) This is, of course, an approximation; the real figure will probably be a bit different because of many issues, such as varying exit policies, socket limitations, differences between the cost of handling encrypted OR traffic and handling traffic to the network, and so on. It doesn't go the other way around, btw: since all exits can be relays, it doesn't hurt to have an all-exit network. There's also directory caches. More of those could never hurt, especially on middleman nodes. By the way, this kind of came up in a recent change we made that should show up in 0.1.2.2-alpha: the new code avoids using exits as relays nodes when there are lots more non-exits than exits. yrs, -- Nick Mathewson
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