[Cake] fq_codel on 3g network in Mauritius

Jonathan Morton chromatix99 at gmail.com
Tue Jul 19 04:09:27 EDT 2016

> On 19 Jul, 2016, at 07:29, Loganaden Velvindron <loganaden at gmail.com> wrote:
> I've been playing with fq_codel on 3g internet connection. the 3g
> internet box has no bridge mode, and just forwards every packet to the
> Openwrt router.
> Here are the results without:
> http://www.dslreports.com/speedtest/4470186
> And here is the result with fq_codel on and 300 ms target latency:
> http://www.dslreports.com/speedtest/4470286
> Is there anything that could be done to get the rating up to A+ by
> tweaking the code ?

You say fq_codel, rather than Cake.  Presumably it is paired with some sort of shaper, such as HTB?  This is important, because I think the shaper is influencing part of your results.

On downstream, you have one high latency sample (750ms) in the middle of a series of reasonable ones (250ms).  This implies a momentary glitch in your connection, which isn’t unusual with wireless links.  Re-measuring might eliminate it.

On upstream, you have two very high latency samples at the *beginning* of the run, which then clear out to approximately the baseline latency.  This is a classic sign that your shaper is letting a burst of traffic through before actually starting to control it, which is typical behaviour for token-bucket shapers.  That initial burst collects in the dumb queue of your 3G modem and takes time to drain away.

Cake uses a shaper carefully designed to *not* burst in that manner, while still maintaining full throughput regardless of timer resolution and latency.  Using Cake instead of fq_codel+HTB will therefore probably improve your upload characteristics.

 - Jonathan Morton

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