[Cake] Per-host fairness

moeller0 moeller0 at gmx.de
Tue Oct 18 04:44:59 EDT 2016

Hi Georgios,

> On Oct 18, 2016, at 03:33 , Georgios Amanakis <g_amanakis at yahoo.com> wrote:
> I tried with "besteffort dual-dsthost nat" on ifb ingress and
> “besteffort dual-srchost nat" on WAN egress,


> and when doing simple
> things (i.e. downloading from a couple of websites) the bandwidth is
> divided fair per-host, i.e 1:1 between A and B.

	Okay, does this stay fair if one of the hosts open a bunch of websites at the same time? Does the download test also give per-host fairness if the number of downloads is massively imbalanced between the hosts?

> However, when one of
> the hosts is using bittorrent, he also gets most of the bandwidth, i.e.
> if total ingress bandwidth is 3300kbit, A is using bittorrent and gets
> 2900kbit, B is downloading from a single website and gets 400kbit.

	Bit-torrent is a hard problem it seems, especially the cobalts branch that you test is supposed to better deal with it though so this is abit of a puzzle. How long are your tests? Are you looking only at a few seconds or something like >30 seconds (maybe the shaper needs time to reach equilibrium)? What happens in the upload during theses tests? I also wonder how many new torrent connections are established during the test or are the torrent flows long lived?

	I probably would try to instantiate cake not on the wan but on a lan interface of the router and re-do the test without the “nat” option just to reduce the number of tested parts. If you should do this, please remember that ingress and egress are per interface, so downloads from the internet use the LAN-egress while internet-uploads use LAN-ingress, so make sure to switch the bandwidth definitions for your two cake instances accordingly. 
	Finally could you post the results of “tc -s qdisc” before, during and after your bit-torrent tests for the test you just reported and the LAN test in case you ago that route.

Best Regards

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