[tor-dev] Proposal Waterfilling

[teor]

Hi,

I have some more questions:

On 18 Jan 2018, at 11:03, teor <teor2345 at gmail.com> wrote:

>>>>> Unanswered questions:

The Tor network has been experiencing excessive load on guards and 
middles since December 2017.

Does the waterfilling proposal make excessive load on guards worse, by
allocating more guard weight to lower capacity relays?
Is the extra security worth the increased risk of failure?

Does the waterfilling proposal make excessive load on middles better, by
allocating more middle weight to higher capacity relays?
Is there a cascading failure mode, where excess middle weight overwhelms
our top relays one by one? (It seems unlikely.)


I also have another practical question:

We struggle to have time to maintain the current bandwidth authority
system.

Is it a good idea to make it more complicated?
Who will maintain the new code we add to Tor to implement waterfilling?
Who will build the analysis tools to show that waterfilling benefits the
network?

Do the benefits of waterfilling justify this extra effort?

And even if they do, should we focus on getting the bandwidth authorities
in a maintainable state, before adding new features?
(I just gave similar advice to another developer who has some great ideas
about improving bandwidth measurement.)

>>>>> What about the feedback loop between this new allocation system
>>>>> and the bandwidth authorities?
>>>>> 
>>>> I am sorry, I don't really understand why a feedback loop is needed. Measuring bandwidth and producing bandwidth-weights seems orthogonal to me.
>>> You do not need to add a feedback loop, one already exists:
>>> 1. Consensus weights on guards and middles change
>>> 2. Client use of guards and middles change
>>> 3. Bandwidth authority measurements of guards and middles change
>>> 4. Repeat from 1
>>> 
>>> My question is:
>>> 
>>> How does this existing feedback loop affect your proposal?
>>> Does it increase or reduce the size of the guard and middle weight changes?
>> 
>> I have added those questions to the proposal. This looks difficult to know.
> 
> Can shadow simulate this?

I am still interested in this feedback loop.
If it fails to converge, the system will break down.

T