Not powersave of any component in my control. Powersave of the CMTS? I'd expect high latency for idle pings in that case too.
On 16 January 2018 at 20:52, Dave Taht <[email protected]> wrote: > Power save? > > On Tue, Jan 16, 2018 at 11:36 AM, Arie <[email protected]> wrote: > > Recently I accidentally discovered something quite odd about my home > DOCSIS > > connection (shaped with cake) while running a flent rrul test. > > During the flent rrul test, another machine in my home had started a > Steam > > game update, this opened somewhere between 8-12 connections and > saturated my > > downstream. > > > > The interesting part was the resulting rrul graph, showing perfect > latency > > control during the test, but 100-150ms of bufferbloat at the very start > and > > end of the rrul graph (when rrul is idle, just pinging). > > > > Instead of a Steam download I started an iperf3 client on a remote > machine > > that opened 16 connections to a LAN machine. Same behavior as the Steam > > download. > > > > At first I thought this was a bug with cake, but no matter how I tuned > cake > > (limiting my 400/40 connection to 50/20 for example), the behavior was > > similar. > > I tried fq_codel+htb, and got similar results to cake, high latency > before > > the rrul test kicked off, great latency while rrul was doing its up and > > downloads. > > > > So I swapped out my self-compile LEDE router with an Edgerouter ER-X with > > both stock and LEDE firmware, both with fq_codel and cake (on both stock > and > > LEDE firmware). Same results. > > Even without any SQM active, the rrul test still improved the latency of > my > > connection when it's also downloading from 8+ connections at the same > time. > > > > I managed to take the flent rrul test out of the equation by starting a > > hping3 "flood" to the hop next of my cable modem. > > > >> hping3 -2 -d 0 -s 10080 -k -p 80 -i u100 > >> first-hop-or-ISP-gateway-goes-here > > > > > > This also fixed the latency while many downloads were running by sending > > about 300KB/s of empty UDP packets to some unresponsive port on my ISPs > > local gateway. > > > > I'm puzzled by this result, somehow sending 300KB/s of empty packets > > upstream drastically improves the latency of my connection when it's > > receiving many downloads. > > > > Equipment used: > > Cisco EPC3212 cable modem (8x4 EuroDOCSIS 3.0) > > Linksys WRT1900ACS router with LEDE > > Ubiquiti Edgerouter ER-X with both EdgeOS (stock) and LEDE > > > > > > > > > > _______________________________________________ > > Bloat mailing list > > [email protected] > > https://lists.bufferbloat.net/listinfo/bloat > > > > > > -- > > Dave Täht > CEO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-669-226-2619 >
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