should we consider making CoDel the default to combat bufferbloat?

[Glen Turner]

Hi folks:

I would have thought that it should be the system program which brings up the interface which should set the queuing behaviour. Neither the kernel nor systems know the intent of the use of the interface, and thus if CoDel, FIFO, or other AQM is appropriate.

Consider an ethernet interface, all using the same physical hardware:

 - enterprise LAN interface -- CoDel

 - ADSL link with PPP over ethernet -- ppp0 should run Codel, eth0 should run a short prioritised FIFO.

 - data centre LAN interface -- hierarchical queuing with a high priority, random drop queue for control plane traffic (LACP, spanning tree, etc) and CoDel for other traffic.

Intent is vital in setting the correct AQM for each interface. The program which configures interfaces (NetworkManager, systemd-networkd, ...) is where intent is best known.

-glen