[tor-dev] Scaling tor for a global population

teor teor2345 at gmail.com
Sun Sep 28 12:41:07 UTC 2014

On 27 Sep 2014, at 10:18 , tor-dev-request at lists.torproject.org wrote:
> Date: Fri, 26 Sep 2014 17:18:07 -0700
> From: Mike Perry <mikeperry at torproject.org>
> To: tor-dev at lists.torproject.org
> Subject: Re: [tor-dev] Scaling tor for a global population
> 2. Cut off relays below the median capacity, and turn them into bridges. 
>    Relays in the top 10% of the network are 164 times faster than
>    relays in the 50-60% range, 1400 times faster than relays in the 
>    70-80% range, and 35000 times faster than relays in the 90-100% range.
>    In fact, many relays are so slow that they provide less bytes to the
>    network than it costs to tell all of our users about them. There
>    should be a sweet spot where we can set this cutoff such that the
>    overhead from directory activity balances the loss of capacity from
>    these relays, as a function of userbase size.
>    Result: ~2X reduction in consensus and directory size.

Do these extra relays function as spare (albeit slower) capacity in the network?
If so, we'd have to be careful to set the cut-off low enough that any spikes in usage could be accommodated.

Also, doesn't reducing the number of routers in the consensus risk harming network diversity?

I understand that if these routers are a net burden on the network, then they're not actually contributing much to diversity overall. 

But what about users with obscure configurations like "New Zealand routers only", or "custom list of 20 trusted routers"? (Is a restricted set of routers a common enough use case?)
Do we risk pulling the data they need from the consensus?
Then again, users with these sorts of configurations are probably technically savvy enough to fix any issues that occur with any changeover.


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