[Bloat] Detecting bufferbloat from outside a node

[Neil Davies]

On 27 Apr 2015, at 11:52, Toke Høiland-Jørgensen <toke at toke.dk> wrote:

> Neil Davies <neil.davies at pnsol.com> writes:
> 
>> The interesting thing is making all those local decisions add up to a
>> (set of) end-to-end outcomes, and the answer is not to make the same
>> decision(s) everywhere - unfortunately that doesn’t stack up.
> 
> Yes, well, I do also like the E2E principle of not making too many
> decisions within the network, instead letting the endpoints sort it out.
> For me, the fight against bufferbloat is mostly about restoring the
> assumptions that it has eroded (i.e. "packet loss is not to be feared,
> but on the contrary is an important indicator that we're hitting
> congestion"). I'd really rather prefer the network itself to be fairly
> dumb...

I don't think that the E2E principle can manage the emerging performance
hazards that are arising. We've seen this recently in practice: take a look
at http://www.martingeddes.com/how-far-can-the-internet-scale/ - it is based
on a real problem we'd encountered.

In someways this is just control theory 101 rearing its head... in another it
is a large technical challenge for internet provision.

>> We have (some level) of control over our “universe of discourse” - my
>> joke with my mates at CERN is that they only have one universe to
>> investigate, we can create three in one day and still be home in time
>> for tea!
> 
> Hehe, quite. That is both fascinating and frustrating! :)
> 
> -Toke