Tuesday, May 27, 2014

Disabling shaping in one direction with CeroWRT

Another test Dave Taht asked for was to disable the downstream shaper and see what happened.  It wasn't pretty.  So I also disabled the upstream shaper.  Also not pretty.  Then I went back to using the shaper enabled in both directions.

Baseline using fq_codel and 54.5Mbps downstream limit and 10Mbps upstream limit:

Now, turning off the downstream shaper yields:

This indicates (to me), that there's very excessive buffering at the CMTS, and the downstream shaper is badly needed to keep it under control.

So I re-enabled downstream, and disabled the upstream shaper:

Again, not ideal.  It's interesting seeing how the shapers interact with the traffic in the other direction as well.  Because their ACKs are going through the other path, disabling shaping on one clearly effects the other.