[Cake] Cake strange behaviour

Kevin Darbyshire-Bryant kevin at darbyshire-bryant.me.uk
Sat Jul 16 07:53:20 EDT 2016

On 16/07/16 11:59, Dave Täht wrote:
> I would repeat the same test with htb+fq_codel.

Hi Dave,

That's more challenging than it sounds - reproducing the test scenario 
would require the windows box going back in time.  What could it be 
doing that so far any of the flent tests fail to replicate?  Hmmm, so 
far I've used a local flent server...I wonder if RTT is at play here?


> On 7/16/16 11:35 AM, Kevin Darbyshire-Bryant wrote:
>> 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
>> http://www.thinkbroadband.com/ping/share/9822cb5160582fa6abee29b60d807766-16-07-2016.html
>> 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.
>> Kevin
>> _______________________________________________
>> Cake mailing list
>> Cake at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/cake
> _______________________________________________
> Cake mailing list
> Cake at lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/cake

More information about the Cake mailing list