Re: [Ecn-sane] [tsvwg] per-flow scheduling

["Bless, Roland (TM)" <roland.bless@kit.edu>]

Hi,

Am 26.06.19 um 18:31 schrieb David P. Reed:

> The idea that "link utilization" of 100% must be achieved is why we got
> bufferbloat designed into routers. It's a worm's eye perspective. To

You are right, but IMHO it is even worse, because it is an
artefact of the particular loss-based TCP congestion control
as it was designed and the correspondingly derived "BDP buffer size"
rule. The loss-based AIMD congestion control is able to keep up the
utilization then, because it uses the systematically built standing
queue during its back-off after a packet loss. That essentially keeps
the sending rate at the same level. However, now we know that avoiding
queuing delay is important, we can also design better congestion
controls that do not fill the available buffer capacity up to exhaustion
and that do not require standing queues to keep up link utilization.

However, as you also wrote, the positive and negative effects of
existing buffers depend a lot on the particular traffic pattern and this
has also changed much during the last decades. So I think that revising
the "buffer size" discussion could be useful...

Aside from that I find the SCE proposal very useful, because it allows
to provide an additional level of congestion signalling that could
be used by various congestion control schemes.

Regards,
 Roland