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Standard User jaba
(learned) Tue 13-May-14 21:58:02
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Upload speed and line drops on ADSL2+


[link to this post]
 
When my exchange was upgraded to 21CN this year I saw an increase in connection speed but also a couple of loss of PPP session daily. Eventually I got Plusnet to switch on interleaving which then immediately gave me a 100% stable line.

Then last week I decided that I would take advantage of faster uploads and got Plusnet to uncap my upload speed, it went up from 446 to 864. They told me that this would not have any effect on my download speed, which it hasn't. But I am now getting random disconnects a couple of times a day.
It looks as though interleaving is still on and I have asked Plusnet to confirm this to me

My question is does uncapping the upload speed have any known effect on download or line stability ?
Administrator MrSaffron
(staff) Tue 13-May-14 23:02:51
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Re: Upload speed and line drops on ADSL2+


[re: jaba] [link to this post]
 
Running upload at a rate adaptive speed can mean you see disconnects due to noise in the upstream frequencies. Generally very rare and usually a sign of micro filters that need some work

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User jaba
(learned) Wed 14-May-14 18:30:28
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Re: Upload speed and line drops on ADSL2+


[re: MrSaffron] [link to this post]
 
You have great insight Andrew. I just checked the Upstream noise level, its changed with the uncapping from 17db to 5.9db. So there is much less margin there. Are the Tx frequencies higher than the Rx I wonder.
I have an ADSLNation face plate and do not know how robust these are at filtering.
These are my current stats :

ADSL Link Downstream Upstream
Connection Speed 5127 kbps 864 kbps
Line Attenuation 53.5 db 33.6 db
Noise Margin 7.7 db 5.9 db

I am inclined to get the line capped again to get back the reliability. This is much more important than quicker upload times for my occasional FTPing.


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Standard User jaba
(learned) Fri 16-May-14 07:43:39
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Re: Upload speed and line drops on ADSL2+


[re: jaba] [link to this post]
 
I rang Plusnet yesterday as I was getting an increasing number of disconnections.
It turns out that they had switched OFF interleaving in both directions when the upstream rate was set to adaptive !!!
Thank you very much Plusnet..................
Standard User jaba
(learned) Sat 17-May-14 00:12:50
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Re: Upload speed and line drops on ADSL2+


[re: jaba] [link to this post]
 
Further developments.......
PN initiated a line retrain today as well as interleaving switched on again.

Interestingly the retrain now starts with a 3db snr. Which has tonight now dropped down to zero or thereabouts and the modem is hanging on. Impressive.
Here are the current stats :

/usr/sbin/adslctl: ADSL driver and PHY status
Status: ShowtimeRetrain Reason: 1
Channel: FAST, Upstream rate = 947 Kbps, Downstream rate = 6891 Kbps
Link Power State: L0
Mode: ADSL2+
Channel: Fast
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 0.3 4.6
Attn(dB): 53.5 33.7
Pwr(dBm): 0.0 12.8
Max(Kbps): 6948 912
Rate (Kbps): 6891 947



I have never synced at 6Mb before as the exchange is about 3 miles away !

Plusnet however are spoiling the speed gain by changing my Current Line Speed during the afternoon from 4.9 down to 4.5. This, when I have not been connected at anywhere near 4.5.

Is there any way to get Plusnet to stop doing this ? Or better still to switch it off altogether.
Standard User tommy45
(knowledge is power) Sat 17-May-14 01:54:49
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Re: Upload speed and line drops on ADSL2+


[re: jaba] [link to this post]
 
Sounds like you may have a line fault, DLM will be responsible for the changes in speed , interleave and higher margins only serve to hide underlying faults in some cases
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