[Cake] Cake strange behaviour

Kevin Darbyshire-Bryant kevin at darbyshire-bryant.me.uk
Sat Jul 16 05:35:43 EDT 2016

Hi guys,

Encountering some behaviour that I don't understand.  Line is a 40/10 
cake limited to 39000/9840. Overheads 12, 'dual-dsthosts' in ingress, 
'dual-srcshosts' on engress - limiting the on the WAN line. Take a look 
at my ping response graph


Around 20:30 I fired up a windows machine that was behind on its updates 
so it generated a bit of ingress traffic.  Note the comparatively high 
latency (40ms) and stupidly high ping packet loss (50%)  The 3-5ms 
steady (blue) latency you can see is a system backup (so egress traffic) 
running till around 23:00.

The really strange bit is that cake stats show it has only dropped 10 
(yes 10!) packets.

I'm not the only person encountering 'interesting' behaviour with regard 
to windows updates inducing high latency and high packet loss.  It's as 
if cake weren't there managing flows and this is the ISP's rate limiter 
in action.


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