Hi Neil,
On Jul 25, 2014, at 16:27 , Neil Davies <neil.dav...@pnsol.com> wrote:
> Sebastian
>
> On 25 Jul 2014, at 15:17, Sebastian Moeller <moell...@gmx.de> wrote:
>
>> But how do you propose to measure the (bottleneck) link capacity then?
>> It turns out for current CPE and CMTS/DSLAM equipment one typically can not
>> relay on good QoE out of the box, since typically these devices do not use
>> their (largish) buffers wisely. Instead the current remedy is to take back
>> control over the bottleneck link by shaping the actually sent traffic to
>> stay below the hardware link capacity thereby avoiding feeling the
>> consequences of the over-buffering. But to do this is is quite helpful to
>> get an educated guess what the bottleneck links capacity actually is. And
>> for that purpose a speediest seems useful.
>
>
> I totally agree that what you are trying to do is to take control "back" for
> the upstream delay and loss (which is the network level activity that
> directly influences QoE). Observationally the "constraining link" is the
> point at which the delay and loss start to grow as the the offered load is
> increased (there are interesting interactions with the scheduling in the
> CMTS/3GPP node B - but they are tractable) if we don't have direct access to
> the constraint (which in the CPE, for ADSL you have) we track that "quality
> attenuation" inflection point. Saturating the path is a bit of a sledgehammer
> (and has nasty cost/scaling implications).
What else can I do to make sure that my network still works
satisfactory in the “worst case” than to test and tune it for the worst case?
Also, coming from a biology background, I like systems that operate well in the
capacity limited state ;)
>
> I see, as I was replying, Martin has sent you some links to the background.
Interesting read, do you have a pointer on how to calculate deltaQ
though?
best regards
Sebastian
>
> Cheers
>
> Neil
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