[tor-project] The tor network is constrained by.... (meek, exits, etc)

[Tom Ritter]

On 17 January 2017 at 10:11, Karsten Loesing <karsten at torproject.org> wrote:
>> Secondly, I know it's too simplistic to say "Our exits are
>> operating at 85% of capacity, our guards are 65% and our middles at
>> 40%" (for a host of reasons, including guard/middle overlap) but
>> how close can we get to something simple that demonstrates more
>> exits will help the (non-bridge) network the most? (If that is in
>> fact the case!)
>
> I don't know an easy answer to this, but you could look at consensus
> bandwidth weights for a start:
>
> https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n2699
>
> The latest consensus bandwidth weights are:
>
> bandwidth-weights Wbd=0 Wbe=0 Wbg=4127 Wbm=10000 Wdb=10000 Web=10000
> Wed=10000 Wee=10000 Weg=10000 Wem=10000 Wgb=10000 Wgd=0 Wgg=5873
> Wgm=5873 Wmb=10000 Wmd=0 Wme=0 Wmg=4127 Wmm=10000
>
> If you go add many more guards or exits, you should observe how those
> weights change.

I added the weights with human-readable descriptions to
https://consensus-health.torproject.org/

I see the following:
- Exits are never recommended for middle or guard positions
- Guards are equally recommended as non-Guards for exit positions
- Guards are recommended for middle, but as highly as non-Guards

So I'm drawing the following conclusions:
- Exits are a bottleneck, if we had more exit bandwidth, we would see
Exits start to be recommended (even at very low weights) for middle or
guard positions
- We have enough Guards that we can use them as middle relays (albeit
at a lower rate than we'd weight non-Guards)

-tom