What the complexity buys you is that BBRs metrics max_BW, min_RTT, and the
ACK aggregation/batching metrics are actual parameters of the network, and
observable with passive instrumentation of the packet streams.  Traditional
CC is a collection of heuristics to estimate cwnd, which has a clear
interpretation in terms of action (when to send), but the optimal cwnd
can't easily be observed from the packet stream.

I think this alone will have impact, in terms of being able to reason about
CC behaviors.

Thanks,
--MM--
The best way to predict the future is to create it.  - Alan Kay

We must not tolerate intolerance;
       however our response must be carefully measured:
            too strong would be hypocritical and risks spiraling out of
control;
            too weak risks being mistaken for tacit approval.


On Sun, Jul 5, 2020 at 11:13 AM Jonathan Morton <chromatix99@gmail.com>
wrote:

> > On 5 Jul, 2020, at 9:09 pm, Stephen Hemminger <
> stephen@networkplumber.org> wrote:
> >
> > I keep wondering how BBR will respond to intermediaries that aggregate
> packets.
> > At higher speeds, won't packet trains happen and would it not get
> confused
> > by this? Or is its measurement interval long enough that it doesn't
> matter.
>
> Up-thread, there was mention of patches related to wifi.  Aggregation is
> precisely one of the things that would address.  I should note that the
> brief description I gave glossed over a lot of fine details of BBR's
> implementation, which include careful filtering and conditioning of the
> data it gathers about the network path.
>
> I'm not altogether a fan of such complexity.
>
>  - Jonathan Morton
>
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