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FTTC down/up speed asymmetry

oldtimer
Newbie
Posts: 5
Registered: ‎24-06-2009

FTTC down/up speed asymmetry

Hi,
What determines the download/upload ratio? I've noticed other FTTC
users get more balanced ratios. Examples:
http://community.plus.net/forum/index.php/topic,136655.msg1199032.html#msg1199032
- down/up ratio ~5:1
http://community.plus.net/forum/index.php/topic,136670.0.html
- 3:1
Plusnet help page:
http://www.plus.net/support/broadband/speed_guide/broadband_speeds.shtml
Fibre 'up to' 76Mb/s up, 19.5Mb/s down
- 4:1
Our speeds here reported by speedtest.net and speedtest.btwholesale.com
are around 8.96 down/0.38 up - a ratio of around 24:1
There's just over a mile of copper from the street cabinet which
explains the slow download speed, but what is stopping the upload from
being closer to 2Mbit?
Current package is Plusnet Unlimited Fibre
9 REPLIES
Highlighted
Community Veteran
Posts: 38,460
Thanks: 1,031
Fixes: 62
Registered: ‎15-06-2007

Re: FTTC down/up speed asymmetry

It is governed by the line length and quality http://www.thinkbroadband.com/guide/fibre-broadband.html gives an indication although individual lines can have different characteristics
sjptd
Grafter
Posts: 486
Thanks: 4
Registered: ‎01-09-2014

Re: FTTC down/up speed asymmetry

I think the upload tones are lower frequency than the download tones, so some forms of noise (near audio frequency) will have a much greater impact on upload.
It could also be caused by poor filters; shouldn't be the case with a standard install and filtered faceplate, but ...
Or a mild case of star wiring, with some sort of extension coming off a junction box in the incoming feed before it reaches the master socket.
If you've got an unlocked modem a program such as dslstats will show the tones and might give more clue.
Stoker
Grafter
Posts: 91
Thanks: 2
Registered: ‎12-08-2012

Re: FTTC down/up speed asymmetry

Quote from: sjptd
I think the upload tones are lower frequency than the download tones

It's a bit more compicated than that (assuming my spectrum is typical): red is downstream and green is upstream
Community Veteran
Posts: 6,320
Thanks: 86
Fixes: 3
Registered: ‎08-01-2008

Re: FTTC down/up speed asymmetry

And one from mine (around 450m from cabinet)
Call me 'w23'
At any given moment in the universe many things happen. Coincidence is a matter of how close these events are in space, time and relationship.
Opinions expressed in forum posts are those of the poster, others may have different views.
Community Veteran
Posts: 6,320
Thanks: 86
Fixes: 3
Registered: ‎08-01-2008

Re: FTTC down/up speed asymmetry

post removed- something caused quote of above.
Call me 'w23'
At any given moment in the universe many things happen. Coincidence is a matter of how close these events are in space, time and relationship.
Opinions expressed in forum posts are those of the poster, others may have different views.
sjptd
Grafter
Posts: 486
Thanks: 4
Registered: ‎01-09-2014

Re: FTTC down/up speed asymmetry

Thanks Stoker and w23:
I had thought that the upload and download tones were now more overlapping than they used to be on ADSL, but a quick trip to DSLStats indicated that they were not.
I have now made another check, and see that my DSLStats was set up only to display a small proportion of all tones.
I have now moved the Compress/Expand slider and can see the full picture, and my graph is similar to w23's with three upload tone ranges.
Stoker
Grafter
Posts: 91
Thanks: 2
Registered: ‎12-08-2012

Re: FTTC down/up speed asymmetry

I'm about 850m from the cabinet, with some aluminium wiring too, so I don't get anything above tone #2000.
oldtimer
Newbie
Posts: 5
Registered: ‎24-06-2009

Re: FTTC down/up speed asymmetry

Thanks for all the info.
Stoker, w23, sjptd - How are you generating those frequency charts?
I'm almost certain we've got a single copper pair back to the green box... but much of line is above ground, passes through trees and hedges, has probably been there since the 1970s and has been repaired and patched many times.
As far as I know, it's not possible to get much in the way of stats from the modem as it can't be accessed through the Plusnet supplied Thomson/Technicolor TG582n router.
-
...and download has jumped up to 11.4Mbps in the last week but upload is still around 0.39Mbps.
Very frustrating.
I was wondering if our DECT phones might be causing a problem, but they run at GHz frequencies, so it seems unlikely.
Community Veteran
Posts: 6,320
Thanks: 86
Fixes: 3
Registered: ‎08-01-2008

Re: FTTC down/up speed asymmetry

Unlocked (Huawei HG612 only) BT modems have accessible stats, mine come from my all-in-one router (AVM Fritz Box 7390).
Call me 'w23'
At any given moment in the universe many things happen. Coincidence is a matter of how close these events are in space, time and relationship.
Opinions expressed in forum posts are those of the poster, others may have different views.