[Bloat] [Make-wifi-fast] benefits of ack filtering

[Jan Ceuleers]

On 03/12/17 11:35, Juliusz Chroboczek wrote:
> I'm lost here.  What exact problem is the ACK hack supposed to work
> around?  Ridiculous amount of asymmetry in the last-hop WiFi link, or
> outrageous amounts of asymmetry in a transit link beyond the last hop?

My understanding is that the issue that gave rise to this discussion was
concerned with upstream bandwidth conservation in the uplink of a DOCSIS
network by the cable modem dropping a large percentage of upstream TCP ACKs.

One element of that discussion was the question as to whether it was OK
for middleboxes (such as in this case cable modems) to reduce the number
of TCP ACKs, or whether instead the TCP stacks in the endpoints should
be made to send fewer such ACKs in the first place.

I then added more confusion by saying that in the case of wifi-connected
endpoints the upstream TCP ACKs also compete for airtime with the
downstream flow. Of course this no longer has anything to do with the
cable modem.