Re: [Cake] Configuring cake for VDSL2 bridged connection

[Alan Jenkins <alan.christopher.jenkins@gmail.com>]

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On 25/08/16 15:53, techicist@gmail.com wrote:
> Sorry, what is flowblind? Yes, I am using cake :)

flowblind gives you a single queue, who's maximum size is managed by (a 
modified) codel.  It's useful for testing the codel.

In the default (non- flowblind), each stream is randomly assigned to one 
of hundreds of queues.  In fact cake magically avoids flows sharing 
queues until they have to.  Then each queue is treated "fairly" w.r.t 
the bandwidth it can use.

> So is that latency increase when uploading and downloading? And so I should
> be aiming to achieve that as I slowly increase the bandwidth?

That's the general idea, yes.

For looking at latency statistics, FLENT also has a cumulative 
probability graph.

If you'd rather have the numbers summarized for you, you might prefer 
Richard's netperfrunner.  That's what I used to start with. It's not 
100% the same but very close.  (It's designed to only use ping for 
latency, which means it can use as close a target - on the other side of 
the ISP link - as possible.  E.g. taken from "traceroute".  I found that 
was useful for sensitivity).

https://github.com/richb-hanover/CeroWrtScripts

>
> On 24 August 2016 at 20:49, Alan Jenkins <alan.christopher.jenkins@gmail.com
>> wrote:
>> On 24/08/16 20:47, Alan Jenkins wrote:
>>
>> So you can read off (+calculate) overall throughput, in both directions.
>>
>> And it looks like your latency under load rises by only about 2ms.  That's
>> the sort of thing we're aiming for.
>>
>> Pure codel aims for 5ms, so I take it you're using fq_codel.
>>
>> /reads subject line
>>
>> or using standard cake, and not passing `flowblind` to disable the fair
>> queuing
>>
>> And... yes
>>
>> (1500 * 8) / 4_000_000 = 0.003
>>
>> It takes 3ms to transmit a full packet in the slower direction. So when
>> it's busy, ping can be delayed on average by 1.5ms (while the current
>> packet is transmitted).  Something like that anyway.
>>
>>
>> On 24/08/16 20:33, techicist@gmail.com wrote:
>>
>> Thanks for the reply. I understand now 😀
>>
>> What can be taken from these graphs? I'm afraid I really am lost now.
>>
>>
>>
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