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ADSL2+, should it be faster than this?

doob
Dabbler
Posts: 17
Registered: ‎30-07-2007

ADSL2+, should it be faster than this?

I had my account upgraded to ADSL2+ at the beginning of the week, and I have to say I'm a bit underwhelmed by the increase in speed I've seen.
On ADSL1, for the last 8 and a bit months, I've been synced at 8128kpbs, attenuation usually 17/18dB, SNR margin varying around 13dB. Immediately after the upgrade, this changed drastically. Attenuation is now 26dB, SNR margin has been as low as 4dB and as high as 10dB. Initially the downstream speed was ~14mbps, but it's now down around ~12mbps. My setup is a Draytek Vigor 100 modem attached to a Linux box, and I've actually got monitoring set up to graph the stats from the modem, see attached images Smiley
Now, I'm not really complaining, as obviously any increase in speed for free is nice, but I was expecting a bit more than this. A couple of speed estimators I've used online suggest I should be getting around 17mbps with these line stats. Is it likely there's a problem somewhere? Am I expecting too much, or just being impatient? How long should the line take to settle?
51 REPLIES
Community Veteran
Posts: 38,460
Thanks: 1,031
Fixes: 62
Registered: ‎15-06-2007

Re: ADSL2+, should it be faster than this?

That doesn't look right
The attenuation increasing from 18dB to 26dB is frankly terrible - it should only increase by about 2dB to 4dB
When you say you were moved to ADSL2 I assume this was part of a move from 20CN to 21CN which involves a wiring change at the exchange. Unless this included a couple of kilometres of extra wire  Grin or they moved the exchange in the process it shouldn't have had that effect.
doob
Dabbler
Posts: 17
Registered: ‎30-07-2007

Re: ADSL2+, should it be faster than this?

Correct, this was due to my exchange being upgraded to 21CN recently, I got the (presumably) automated message from PN telling me that my line would be switched over.
Reading around how ADSL works I was expecting the attenuation to increase, but was a bit surprised by how much it changed, so good to have my suspicions confirmed. In a straight line I'm less than 1km from my exchange, so I doubt anything quite that crazy will have been done to the line Smiley I assume it's essentially moving the line from an ADSL1 "endpoint" to an ADSL2+ "endpoint" within the exchange.
One other thing to note is that I have had a few disconnects during the day since the switchover. I had put that down the the line sorting itself out, but could that be indicative of a problem?
Community Veteran
Posts: 38,460
Thanks: 1,031
Fixes: 62
Registered: ‎15-06-2007

Re: ADSL2+, should it be faster than this?

I have no idea but looking at the graphs in detail I suspect a reporting problem with the router or I am completely misreading the graphs
Before the changeover
Near attenuation 17dB
Far attenuation  21dB
After changeover
Near attenuation 26dB
Far attenuation  11dB initially then 6dB
Normally the upstream attenuation should be about half the downstream and "near" is usually the upstream
Do you have another modem or router you can try
doob
Dabbler
Posts: 17
Registered: ‎30-07-2007

Re: ADSL2+, should it be faster than this?

It's possible that I'm misinterpreting the stats from the modem when creating the graphs, but I thought I'd got it right. Here's the raw data the modem reports:
  --------------------------- ATU-R Info (hw: annex A, f/w: annex A) -----------
  Running Mode            : ADSL2+(G.992.5)       State                : SHOWTIME
  DS Actual Rate          : 12028000 bps   US Actual Rate       :  1100000 bps
  DS Attainable Rate      : 12028000 bps   US Attainable Rate   :  1104000 bps
  DS Path Mode            :  Interleave    US Path Mode         :  Interleave
  NE Current Attenuation  :       26 dB    Cur SNR Margin       :        7  dB
  DS actual PSD           :    11. 9 dB    US actual PSD        :    20. 4   dB
  ADSL Firmware Version   : 131701_A
 -------------------------------- ATU-C Info ---------------------------------
  Far Current Attenuation :        6 dB    Far SNR Margin       :       11  dB
  CO ITU Version[0]       : 00004946       CO ITU Version[1]    : 0000544e
  DSLAM CHIPSET VENDOR    : < IFTN >

I do have an old Netgear DG634 I can try, which I think supports 2+, I'll give that a try tonight. If nothing else it should help confirm I'm getting the stats the right way round.
Community Veteran
Posts: 38,460
Thanks: 1,031
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Registered: ‎15-06-2007

Re: ADSL2+, should it be faster than this?

It looks like they are the right way round - I was basing my comment on a Google search - which doesn't explain why the upstream attenuation has dropped so low
It will be interesting to see what the Netgear reports
x47c
Grafter
Posts: 878
Thanks: 1
Registered: ‎14-08-2009

Re: ADSL2+, should it be faster than this?

Well, US and DS powers (PSD) are back to front
US should be around 12 and DS should be around 20
NB your old netgear may report the DS power as 0 - this is not a fault - its a known bug in many routers
doob
Dabbler
Posts: 17
Registered: ‎30-07-2007

Re: ADSL2+, should it be faster than this?

I did wonder about the PSD figures. I can't claim to understand exactly what it's representing, but is it roughly the strength of the signal being sent? In which case it would be odd that the exchange is sending a weaker signal to my modem than the modem is sending back to the exchange. What is more likely: that the modem is reporting them the wrong way round, or that something is configured wrong somewhere (at the exchange?) and those actually are the true values (in which case that might explain the slow downstream speed and faster than expected upstream speed)?
When I was on ADSL1, the same modem did report 0 for both of these.
doob
Dabbler
Posts: 17
Registered: ‎30-07-2007

Re: ADSL2+, should it be faster than this?

The DG632 actually gets a slightly better connection, but not by much:
US Connection Rate:     1067    DS Connection Rate:     14963
DS Line Attenuation:    22      DS Margin:              6
US Line Attenuation:    11      US Margin:              7
US Transmit Power :    0      DS Transmit Power:      0
Showtime Count:        1      DS Max Attainable Bit Rate:    16884
BitSwap:                1      US Max Attainable Bit Rate:    1068000

Can someone from Plusnet confirm whether this may indicate a problem with the line? From what I can tell, the increase in attenuation I've seen when switching to ADSL2+ is higher than would be expected, and even at that attenuation, I'm not getting the speeds I should. Both devices I've tested with were plugged into the master socket, which in my house isn't an NTE5, but a normal double socket plate.
doob
Dabbler
Posts: 17
Registered: ‎30-07-2007

Re: ADSL2+, should it be faster than this?

I'm still getting 1, sometimes 2 disconnections each day as well. The PN line speed says:
Quote from: plusnet
Estimated line speed:
    8Mb (Accurate to within +/- 1Mbit) - Checked on 2012-06-15 10:35:55
Current line speed:
    11.9 Mb

Could something here be limiting my line? Or am I simply making it take longer to settle by keeping on fiddling with it? Smiley
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: ‎18-07-2007

Re: ADSL2+, should it be faster than this?

Hi there,
Just checked and your profile matches across ours and BTs sides at 11900, this ties in well with the estimate given for your line at http://www.dslchecker.bt.com/adsl/adslchecker.welcome though there are one or two disconnections showing. I'd recommend checking filters and trying the router in the test socket if possible to see if this eliminates the drops, if not then we'd need to escalate this as a fault for you - please run through the wizard at http://faults.plus.net and we'll pick it up once that's been done (if the fault is still apparent following testing).
doob
Dabbler
Posts: 17
Registered: ‎30-07-2007

Re: ADSL2+, should it be faster than this?

I don't have a test socket as such as my master socket isn't an NTE5, but the modem is plugged into the master socket (via a filter obviously) which is wired directly to the phone line coming from outside, so is equivalent to a test socket. I'll leave it alone for a few days and see if I get any more disconnects. I've been using the current filter for years with no problems, but I do have another I can try, which I will also do for a few days. Both the filters are quite old, is it possible they're not fully compatible with ADSL2+?
I realise that the speeds are within the expected range for my line, it's just that given that my ADSL1 connection was so good, I was expecting the ADSL2+ connection to be a lot faster than this. Is that an unrealistic expectation?
Thanks.
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: ‎18-07-2007

Re: ADSL2+, should it be faster than this?

Hmm, see what you're saying. We could try dropping the downstream SNR margin to 6 which should give you an extra 1.5Mb or so on your sync speed, but I'd be reluctant to do that while it's still dropping.
Having checked your routers also, I'm not convinced that either are specifically ADSL2+ compatible - I realise they are working and the netgear especially is showing the correct protocol (I can see on further googling that an official ADSL2+ compatible firmware update has been released) but I would seriously recommend trying a more recent router that was released with ADSL2+ in mind if that's possible.
doob
Dabbler
Posts: 17
Registered: ‎30-07-2007

Re: ADSL2+, should it be faster than this?

The Draytek is definitely supposed to be ADSL2+ compatible, both these pages list ITU-T G.992.5:
http://www.broadbandbuyer.co.uk/Shop/Specifications.asp?ProductID=4276
http://web.archive.org/web/20080120153108/http://www.draytek.co.uk/products/vigor100.html (it's not listed on the Draytek site currently, but the Wayback Machine has the page).
I had to upgrade the FW on the Netgear before it would sync at > 8mpbs, the Draytek is already on the latest firmware.
Is it possible that the old microfilters don't support ADSL2+?
Edit: and the Draytek even says "ADSL2/2+" on the front Smiley
Plusnet Help Team
Plusnet Help Team
Posts: 13,538
Thanks: 252
Fixes: 69
Registered: ‎27-04-2007

Re: ADSL2+, should it be faster than this?

It at least sounds like the Draytek should be compatible then, with regards to filters there's no such thing as an ADSL 2 compliant filter as far as I'm aware. However Newer filters IMHO are more likely to be of a better quality.
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 Adam Walker
 Plusnet Help Team