I see that many of the sqm configuration guides are mainly related to the docsis connection type. In my case, the provider provides me with an ethernet cable from their switch, which is directly connected to my openwrt router. The physical eth connection and the speed of my internet plan are both 100mbit/s. When I check my internet connection speed using tools like speedtest, I see a real download/upload speed of around 93-94mbit/s. I am unsure how to configure sqm for my ethernet connection type. To begin with, in Link layer Adaptation, I set the following parameters: Per Packet Overhead (bytes)=44, and Minimum packet size=84. I want to know what channel speed I should set for wan, so that if the channel is loaded, for example, up to 50mbit/s (this is a limit that I will set in the application itself, such as a torrent client) The remaining channel speed of 35-40mbit is sufficient for online games and video conferences without lag. Xiaomi Ax3000T Router
In that case set overhead to 44, mpu to 84, egress rate to 99 and ingress rate to 90 Mbps, that should be a decent starting point.
I noticed that cake’s ethernetpreset equals to noatm overhead 38 mpu 84. I’m curious about overhead 38 vs 44. Why 44 and not 38?
44 works for most realistic ATM encapsulations as well and also covers a single VLAN on ethernet. It turns out that getting the overhead exact is not all that important as long as one errs on the side of too much, so the 44 default recommendation aims to be correct for most expected cases instead of making picking this number a science where folks need to bring detailed knowledge of what happens on their link. For ATM/AAL5 we can empirically deduce the relevant overhead, but for other link layers we typically can not do so reliably.