so nice to know cake has made it to russia!!! On Fri, Apr 3, 2020 at 11:46 AM Alexander E. Patrakov <patra...@gmail.com> wrote: > > Hello, > > there is a recurring cargo cult pattern in many forums (e.g. OpenWRT): > people keep suggesting various overhead compensation parameters to > tc-cake without checking what's the bottleneck. They just assume that > it is always related to the link-layer technology of the connection. > > This assumption is mostly incorrect, and this needs to be explained in > the manual page to stop the cargo cult. E.g., here in Russia, in the > past year, I had a 1Gbit/s link (1000BASE-X) but they shaped my > connection down to 500 Mbit/s because that's the bandwidth that I paid > for. I.e. the link from my router to the ISP equipment was not the > bottleneck, it was the ISP's shaper. > > How about the following addition to the tc-cake(8) manual page, just > before "Manual Overhead Specification"? Feel free to edit. > > General considerations > ------------------------------- > > Do not blindly set the overhead compensation parameters to match the > internet connection link type and protocols running on it. Doing so > makes sense only if that link (and not something further in the path, > like the ISP's shaper) is indeed the bottleneck. > > Example 1: the ADSL modem connects at 18 Mbit/s, but the ISP further > throttles the speed to 15 Mbit/s because that's what the user pays > for, and does so with a shaper that has bufferbloat. Then, the "adsl" > keyword is likely not appropriate, because the ISP's shaper operates > on the IP level. The bandwidth needs to be set slightly below 15 > Mbit/s. > > Example 2: the ADSL modem connects at 18 Mbit/s, and the user pays for > "as fast as the modem can get" connection. Then, the "adsl" keyword is > relevant, and the bandwidth needs to be set to 18 Mbit/s. > > Example 3: the user has a 100BASE-TX Ethernet connection, and pays for > the full 100 Mbit/s bandwidth (i.e. there is no shaper further up). > Then, the "ethernet" keyword is relevant, and the bandwidth needs to > be set to 100 Mbit/s. > > -- > Alexander E. Patrakov > CV: http://pc.cd/PLz7
-- Make Music, Not War Dave Täht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-435-0729 _______________________________________________ Cake mailing list Cake@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/cake