Broadband Related > ADSL Issues
Strange IP Profile compared to throughput speed.
waltergmw:
Gentlefolk,
I wonder if anyone has an explanation for the very low IP profile figure, illustrated below, when compared to the BT throughput figure on this G.DMT ADSL service via a HH6.
Heres a corresponding DSL Reports speed test which is probably nearer the truth as yet another statistical calculation.
http://www.dslreports.com/speedtest/13668605
Here's what newcastle.technical.complaints@bt.com say.
They also refuse to initiate a lift and shift as recommended by the eighth BT Openreach engineer.
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I need to concentrate on this line alone, and no other lines that you may be monitoring. I can’t take into account any other line stats.
There is no reason to change the port with no evidence of a fault (currently). I do not agree that the sync rate is fluctuating substantially, but it does fluctuate. Once again, broadband is ‘rate adaptive’, and it will fluctuate.
A hub reboot will cause a resync, sometimes at a different rate. But as DLM monitors the connection for errors and noise, gradually we’d expect that sync rate to level out over time. This appears to be what’s happening with this line.
I would investigate the IP profile discrepancy if it was causing problems with the throughput. The IP profile has absolutely no bearing on the DSL connection rate, so is not a factor in this case.
Swapping to G993.3 is not an obvious step to take here. There is no reason a circuit performing well below 8mbps should be moved to ADSL2+, and I have seen numerous faults in the past which have been resolved by taking the very opposite measure and moving to 8MB WBC.
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burakkucat:
--- Quote from: waltergmw on April 14, 2017, 09:47:15 AM --- . . . Swapping to G993.3 is not an obvious step to take here. . . .
--- End quote ---
That is either a typo or more nonsense from within BT.
G.992.1 is "G.Dmt".
G.992.3 is "ADSL2"
G.992.5 is "ADSL2+"
G.993.2 is "VDSL2"
If the exchange based equipment is 20CN then only G.992.1 is possible.
If the exchange based equipment is 21CN then, with an appropriate CPE, the circuit can be configured as either G.992.1, G.992.3 or G.992.5 within the settings of the CPE.
Remember --
* G.992.1 has a maximum of 256 sub-carriers
* G.992.3 also has a maximum of 256 sub-carriers but uses a more efficient bit-loading than G.992.1
* G.992.5 has a maximum of 512 sub-carriers and uses the more efficient bit-loading, just like G.992.3Summing up you are, unfortunately, in communication with one of BT's "Numpty Nigels from Newcastle" who really should attend the appropriate training course before attempting what he is currently failing to do.
ejs:
A BTWholesale based ISP only has options of ADSL1 or ADSL2+ though. And some exchange equipment (TSTC) does give slower speeds because it does ADSL2+ badly on long lines. Other exchange equipment automatically switches to ADSL2, or does ADSL2+ at equal performance with ADSL2 on long lines.
kitz:
How odd. In theory it shouldnt be possible to attain those speeds with an IPprofile of 0.34Mbps. Something is niggling me about IPprofiles which I cant quite remember now. Who is the ISP, is it by any chance Plusnet?
Is it on a 20CN exchange? I'm assuming he read meant G993.3 as ADSL2+.
Long lines do tend to perform worse on ADSL2+. As far as BTw is concerned they offer G.DMT or ADSL2+ so I can understand why he has said that.
I believe that we here were the first to start recommending trying G992.3 because it gave the best of both worlds - the benefit of S=1/2 mode without opening up the line to the higher frequencies. Its not something that BT configure and must be over-ridden by settings in the modem. I don't think Openreach are fully aware that some EUs do this.
burakkucat:
--- Quote from: kitz on April 16, 2017, 09:48:38 PM ---I believe that we here were the first to start recommending trying G993.3 . . .
--- End quote ---
Nooo. :no: Not G.993.3 . . . but G.992.3
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