On Wed, Aug 21, 2019 at 12:51 AM Sebastian Gottschall <[email protected]> wrote: > > >> i have seen this already. out plan here is that the user specifies the > >> internet connection type like vdsl2, cable, whatever in case of cake which > >> then will be used > >> as argument > > Good goal, that also is theoretically well supported by cake with its > > multitude of encapsulation/overhead realated keywords. Unfortunately > > reality is not as nice and tidy as this collection of keywords implies, > > There are 8 keywords for ATM/AAL5 based encapsulations (ADSL, ADSL2, > > ADSL2+, ...), 2 for VDSL2, 1 for DOCSIS, 1 for ethernet, for a total of 12 > > that all can be combined with one or more VLAN-tag keywords, for a total of > > 24 to 36 combinations. (And these are not even exhaustive, as e.g. the use > > of ds-lite can increase the per-packet overhead for IPv4 packets by another > > 20 bytes). > > Ideally one would just empirically measure the effective overhead and > > use the "overhead NN mpu NN" keywords instead, but that has issues as > > measuring overhead empirically is simply hard... The best bet would be to > > leverage BEREC to require ISPs to explicitly inform their customers of the > > effective gross-rates and applicable overheads for each link, but I am not > > holding my breath. Over at > > https://openwrt.org/docs/guide-user/network/traffic-shaping/sqm we tried to > > give simplified instructions for setting the overheads for different access > > technologies, but these are not guaranteed to fit everybody (not even most > > users, as we have no numbers about the relative distributions of the > > different encapsulation options). > > > > Best Regards > > "another" Sebastian > > as i said. i just started. lets see if i can find a better solution or a > clever way of auto detecting/measuring the overhead
+1. One of my favorite feynman sayings is "disregard" and we need new thinking here. I note that I maintain anywhere between 6-16 flent (netperf and irtt) servers around the world, and they are mostly underused.... Sometimes I've thought that a "right" approach would be to send a 10 sec full udp burst, each packet pre-timestamped internally, at, say, 100Mbit... and then measure "smoothness" at the receiver and ifconfig interface (accounting for any other traffic along the way). > > Sebastian > > > > > > > -- Dave Täht CTO, TekLibre, LLC http://www.teklibre.com Tel: 1-831-205-9740 _______________________________________________ Cake mailing list [email protected] https://lists.bufferbloat.net/listinfo/cake
