moeller0 via OpenWrt Forum mail@forum.openwrt.org writes:
As far as I can tell, the tome to transfer a packet of a given size
and the bandwidth/transfer rate are strongly correlated ;). So we can
calculate the minimum required rate from packet size and acceptable
queuing increase, but as long as the later is fixed, so will be the
former. I guess this actually does not require too much finesse or
precision, so that just accepting 1ms delay aka access rates >= 12Mbps
to enable ECN for egress by default then.
Well, one refinement could be to take the MTU into account. But as you
say it probably doesn't need that much precision for a default, so just
setting a threshold at 12 Mbps (or even rounding that to 10) would be
fine with me.
The value equation for ingress is still different, because we still
have the fact that using ECN should result in a tighter feed-back loop
and that flow's sender slowing down quicker, which might be a win,
even if the queueing delay increases by more than 1ms. But we can
probably ignore this, 12 Mbps is not that common anymore, and we will
keep a manual over-ride anyways.
For ingress I think we should just keep the current default (ECN on).