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Billion BiPac 7800N and ADSL 2+

scuda
Grafter
Posts: 26
Registered: 04-08-2007

Billion BiPac 7800N and ADSL 2+

I'm on Bideford, Devon exchange (21CN WBC enabled), and since using a Billion BiPac 7800N, I have been unable to acheive an ADSL2+ connection, regardless of router config. Currrent router info is:
BiPac 7800N Router
DSP Firmware Version A2pB025f.d22k
DMT Status                         No Defect
Operational Mode                 G.DMT
Upstream                                 576
Downstream                         2848
SNR Margin(Upstream)         10.0
SNR Margin(Downstream)         5.1
Line Attenuation(Upstream)         31.5
Line Attenuation(Downstream) 56.0
Any useful suggestions, before I consider raising a ticket?
Scuda
12 REPLIES
Moderator
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Registered: 14-04-2007

Re: Billion BiPac 7800N and ADSL 2+

Is your line enabled for 21CN and have you checked in Advanced Configuration / WAN / ADSL Mode that all relevant boxes are ticked.

Customer and Forum Moderator.

To argue with someone who has renounced the use of reason is like administering medicine to the dead - Thomas Paine
scuda
Grafter
Posts: 26
Registered: 04-08-2007

Re: Billion BiPac 7800N and ADSL 2+

Yes to all those
Scuda
adie:quote
scuda
Grafter
Posts: 26
Registered: 04-08-2007

Re: Billion BiPac 7800N and ADSL 2+

More info for Strat:
Plusnet migrated the line to 21CN during Feb '12.
Router ADSL settings are:
WAN Interface
ADSL Mode Annex L [No]  Annex M [No]
Modulator ADSL2 [Yes] ADSL2+ [Yes] G.Lite [No] T1.413 [No] G.Dmt [Yes]
Capability SRA Enable [No]
PhyR Upstream [No] Downstream [Yes]
Hope that helps?
Scuda
Superuser
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Registered: 30-07-2007

Re: Billion BiPac 7800N and ADSL 2+

With that attenuation
Quote
Line Attenuation(Downstream)  56.0
its unlikely that ADSL2+ would give much(if any) speed improvement. Given that, Its possible that PlusNet migrated you to 21CN but on an ADSL1 profile.
scuda
Grafter
Posts: 26
Registered: 04-08-2007

Re: Billion BiPac 7800N and ADSL 2+

I did wonder if the distance fom the exchange would be a limiting factor. Do you think that PN would test for a higher profile, if asked?
Anyone feel free to comment?
Scuda
x47c
Grafter
Posts: 878
Registered: 14-08-2009

Re: Billion BiPac 7800N and ADSL 2+

Sometimes ADSL2+ on a very long line can be worse than ADSL1.
This is because:
The additional higher frequencies used by ADSL2+ degrade more on longer lines so as to become unuseable at the router end of the line.
Rather than merely 'disappear' the part of the ADSL2+ signal on these higher frequencies becomes and adds to general noise in the background on the line.
Hence the SNRmargin drops and so the net effect is a lowering of the sync speed when the line is run on ADSL2+ compared to ADSL1
If the service was restricted to ADSL1 these higher frequencies signal parts would not be present.
So longer lines are provisoned on ADSL1 not ADSL2+. I believe the break point is generally regarded as a sync of 4000.  Anything more would benefit from 2+ and anything less should be left on 1
Usual caveat of course is that each line is different:- you get some long ultra quiet lines and some short but very noisy lines.
No idea if PN are prepared to try out ADSL2+ on your line - you can only ask and see what response you get.......................................
scuda
Grafter
Posts: 26
Registered: 04-08-2007

Re: Billion BiPac 7800N and ADSL 2+

Thank you for the very interesting info, x47c. Maybe I will chat to PN, but perhaps I'm getting the best they can provide!  (Bideford gets FTTC in 2013 (ish), so may wait and see!).
Scuda
Superuser
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Registered: 06-04-2007

Re: Billion BiPac 7800N and ADSL 2+

Plusnet's usual practice is to provision ADSL1 (G.DMT) on 21CN connections where the sync speed is expected to be under 4000kbps because experience shows that is likely to give the most stable service. However that usually goes with an upstream sync speed of 448kbps whereas yours (576kbps) is higher than that.
So I wonder if ADSL1 is not forced but results from router/exchange sync negotiation. Huh
David
scuda
Grafter
Posts: 26
Registered: 04-08-2007

Re: Billion BiPac 7800N and ADSL 2+

Quote from: spraxyt
So I wonder if ADSL1 is not forced but results from router/exchange sync negotiation. Huh

An interesting observation. With that in mind, I have just changed the router settings to use ADSL2 and ADSL2+ only, then rebooted. Sadly, even after a good few minutes, there was no sync at all, I had to add G.DMT again and reboot to get broadband back. I think I will look deeper into the settings menus of the router, maybe I've missed something. (anyone with a BiPAC 7800N who can chip in?).
Scuda
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Re: Billion BiPac 7800N and ADSL 2+

7800N and ADSL2+
Mode settings attached.

Customer and Forum Moderator.

To argue with someone who has renounced the use of reason is like administering medicine to the dead - Thomas Paine
scuda
Grafter
Posts: 26
Registered: 04-08-2007

Re: Billion BiPac 7800N and ADSL 2+

Thanks, Strat, pretty close to what I have (see Reply #3 above).
Scuda
Community Veteran
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Registered: 31-08-2007

Re: Billion BiPac 7800N and ADSL 2+

If you are going to play around with your modem/router's configuration and restart like this repeatedly (and at any time you want to reboot/resync) can I suggest you adopt the following method -
Do a Disconnect of your PPP Internet session with the ISP - you need to login to the modem/router interface and look for the Disconnect button to click on.
Now wait a few minutes, power down. Then wait 10 minutes (with the line disconnected - during this time alter the modem/router configuration, you can reboot as may times as you like offline to make sure your changes have stuck, also swap any filters, or the modem/router, connect to test socket, etc. - it doesn't matter if you take longer than 10 minutes) and then power up again & connect to the line (You may need to login to the modem/router and click on Connect to re-establish the PPP Internet session). Check the stats immediately (The Noise Margin [SNRM] shown is usually the current Target Noise Margin).
I usually recommend you do this no more than 5 times in an hour, and then leave it alone for the rest of the day.  Remember the reason for this procedure is to help prevent the exchange DLM from thinking you have a dropping connection with the possible consequences of a raised Target SNRM or a banded connection..
You can use the Disconnect/Connect (without a power down) to Gateway hop.