[Cerowrt-devel] Correctly calculating overheads on unknown connections

[Alan Goodman]

On 22/09/14 20:52, Sebastian Moeller wrote:
>> >This test was ran on a BT Infinity VDSL/FTTC connection with the modem plugged directly into a CentOS 6 machine which is doing PPPoE.  The connection is synced at 80mbit down and 20mbit up.  BT restrict downstream speed to 77.44Mbps IP traffic.
> 	Thank you very much this is the first data set on a VDSL line I have seen, and clearly me hypothesis that overhead detection on PTM carriers will not work with the current code is nicely demonstrated. I need to ponder this a bit more and I might not be able to find a nice solution for those links...

You're welcome.  If you need any more data feel free to drop me a line.

>>>I can run the test on a slower BT connection over the week end if anyone is interested in the results?
>  I would love to see that especially if the other connection is much slower, as I see two possible issues with this data set:

The other connection is actually ADSL2, we probably know what the 
results there will be...  I think I shall run the test on a really slow 
ADSL connection later in the year to double check my overheads though. 
It seems like a very useful tool.

Also thanks for providing some example plots of how it should look. 
That will allow me to better interpret results in future.

> 1) Speed: It might be that your line is fast enough to hide the ATM quantization below another quantization (like the 4KHz symbol rate of the individual carriers) or two many concurrent carriers;)

Would it be useful if I limited my upload speed with say hfsc to 1mbit 
and re-ran the test?

Given the above comments in Sebastian’s very useful emails how would it 
be best to shape these FTTC connections at present?  Without overhead 
set or something else?

Alan