[Bloat] Computer generated congestion control

[Jonathan Morton]

> > I'd like them to put some sane upper bound on the RTT - one compatible
with satellite links, but which would avoid flooding unmanaged buffers to
multi-minute delays.

> The problem is that there aren't any numbers that meet these two criteria.
> Even if you ignore 10G and faster interfaces, a 1Gb/s interface
withsatellite sized latencies is a LOT of data, far more than is needed to
flood a 'normal' link

I very deliberately said "RTT", not "BDP".  TCP stacks already track an
estimate of RTT for various reasons, so in principle they could stop
increasing the congestion window when that RTT reaches some critical value
(1 second, say). The fact that they do not already do so is evidenced by
the observations of multi-minute induced delays in certain circumstances.

And this is not a complete solution by any means. Vegas proved that an
altruistic limit on RTT by an endpoint, with no other measures within the
network, leads to poor fairness between flows. But if the major OSes did
that, more networks would be able to survive overload conditions while
providing some usable service to their users.

- Jonathan Morton
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