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21CN speed disappointing

ComplexP
Grafter
Posts: 98
Registered: 02-10-2009

21CN speed disappointing

I've been on the trial for over 3 weeks now and I've just seen my download profile increase to a 2500 throughput (current sync rate at 3200, although I've seen it as high as 3500 for short times). It doesn't seem inclined to raise much more which is a shame because this is essentially the same speed I was getting on the standard ADSL system.
I used the analysis tool at www.speedtester.bt.com and it confirmed my new throughput but also told me that the potential top speed on my line is over 7000 which makes sense considering I was syncing at over 3000 on normal ADSL. Now I know it's unlikely that I'll ever get a sync rate at 7000 but I was hoping for a least 5000 on ADSL2+.
Perhaps I expected too much but I'm pretty confused that I've basically seen no difference at all yet.
21 REPLIES
Plusnet Staff
Plusnet Staff
Posts: 12,169
Thanks: 18
Fixes: 1
Registered: 04-04-2007

Re: 21CN speed disappointing

Hi,
An ADSL speed of between around 2Mbps to 4.5Mbps doesn't tend to translate into much of an increase in speed on ADSL2+. The technology gives the better increases if you start off with higher than 4.5Mbps or lower than 2Mbps, the bit in the middle stays around the same.
However, if the estimate is higher then it may be worth checking a few things, try the router at the master socket and unplug everything else on phone line and see if that makes any difference, ADSL2+ will notice the errors much more than ADSL will and the DLM certainly will.
Also, can you post your line stats? Worth a look to see whether there's anything obvious of a potential for an increase.
ComplexP
Grafter
Posts: 98
Registered: 02-10-2009

Re: 21CN speed disappointing

Hi Dave
I've been sat in the master socket for almost a week now and have no internal wiring to speak of other than a filter attached to a phone (no extensions or anything like that). I've also tried other filters to no effect. Note that my router currently states I'm on G.992.3 annex A which is ADSL2 not ADSL2+. Don't know if that's significant.
Line Stats:

Uptime: 0 days, 11:13:01
DSL Type: G.992.3 annex A
Bandwidth (Up/Down) [kbps/kbps]: 920 / 3,223
Data Transferred (Sent/Received) [MB/MB] 4.82 / 102.49
Output Power (Up/Down) [dBm]: 12.5 / 0.0
Line Attenuation (Up/Down) [dB]: 27.0 / 46.5
SN Margin (Up/Down) [dB]: 5.0 / 10.0
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 0 / 0
FEC Errors (Up/Down): 4,294,967,264 / 0
CRC Errors (Up/Down): 4,294,967,264 / 100
HEC Errors (Up/Down): 0 / 41  
That noise margin has been fairly solid for quite a while now. Seems to fluctuate between 9 and 10 for down stream. The upsteam margin does look quite low in comparison though although again, I'm not sure if that's significant.
The most glaringly worrying part is the upstream FEC and CRC errors... billionsHuh And I think they start at that collossal figure from a router reboot and then stay exactly the same! What makes it even weirder is that the upstream sync rates are the only part of my connection that have actually seen an improvement (450 to 900 ish).
Any ideas?
Cheers
James
Grafter
Posts: 21,036
Registered: 04-04-2007

Re: 21CN speed disappointing

Hi,
I wouldn't be concerned by the upstream noise margin being low in comparison to the downstream one.  That's fairly normal on ADSL2+.
The number or errors is quite odd.  What happens when you reboot your router?  Do they continue to go up at a pretty crazy speed?  Do you rely on the additional upstream speed?
There's a couple of things that we could do, which may potentially help:
- Cap upstream to 448Kbps
- Apply interleaving
We believe that BT are applying DLM changes based on upstream errors and applying interleaving and capping upstream could help that on both counts.
ComplexP
Grafter
Posts: 98
Registered: 02-10-2009

Re: 21CN speed disappointing

Hello again James  Smiley
Those errors seem to be there straight away from a router reboot and then don't seem to change at all. Very odd. I certainly haven't noticed anything wrong with sending data and everything seems quite stable. Could it be a faulty report from the firmware?Huh
I'd be quite happy to cap the upstream at 448 as long as it helps the downstream. Obviously if the downstream does not increase I assume it can be reversed at a later date?
If possible I'd request that the upstream cap be applied first since I'm less keen on having interleving applied to the line. If the upstream cap has no effect then we could go down the interleving road? That way it provides a better picture of what the issues may have been (and more useful data for you good chaps  Wink  )
Please let me know if this is acceptable and, if so, how long such changes are likely to take effect.
Many thanks.
ComplexP
James
Grafter
Posts: 21,036
Registered: 04-04-2007

Re: 21CN speed disappointing

Hiya,
I've placed an order to cap upstream speeds.
Should complete tomorrow.
ComplexP
Grafter
Posts: 98
Registered: 02-10-2009

Re: 21CN speed disappointing

Excellent, thanks James.
Will I need to reboot the router for the changes to take effect? If this is the case I guess rebooting tomorrow night or Saturday morning might be the best bet?
James
Grafter
Posts: 21,036
Registered: 04-04-2007

Re: 21CN speed disappointing

Saturday morning would be better - your phoneline will be "quieter".
Hopefully it shouldn't need a reboot at all though - there should be a resync when the change is made.
ComplexP
Grafter
Posts: 98
Registered: 02-10-2009

Re: 21CN speed disappointing

Fast work guys; my router resynced overnight. Here's this-morning's stats...


Uptime: 0 days, 4:35:01
DSL Type: G.992.3 annex A
Bandwidth (Up/Down) [kbps/kbps]: 443 / 3,259
Data Transferred (Sent/Received) [MB/MB] 8.68 / 152.95
Output Power (Up/Down) [dBm]: 13.0 / 0.0
Line Attenuation (Up/Down) [dB]: 27.0 / 47.0
SN Margin (Up/Down) [dB]: 19.5 / 10.5
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 12 / 0
Loss of Signal (Local/Remote): 1 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 1 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 0 / 51
HEC Errors (Up/Down): 0 / 27  
So the upstream sync rate has been capped to 448 as agreed but the it seems to have made almost no difference to the downstream  Sad
The upstream noise margin has gone from 5dB to 19.5dB but I'm assuming that's a result of the cap.
Only good thing I can see is that those billions of upstream FEC and CRC errors have gone now which is somewhat encouraging I suppose.
Can't for the life of me figure out how what is wrong. Only thing I can assume is that the speedtest.bt site's info on my line is incorrect and I'm seeing the maximum performance I'm going to get. But they did say a max of 7000 which seems out by a country mile....
Strange.
Any other ideas?
Community Veteran
Posts: 3,789
Registered: 08-06-2007

Re: 21CN speed disappointing

I'm guessing that is a Thompson TG585v7 router?
Not sure if those are compatible with DMT or Routerstats, but I would sure like to get a look at the 'bits per tone' graph - it might highlight something interesting.
B.
ComplexP
Grafter
Posts: 98
Registered: 02-10-2009

Re: 21CN speed disappointing

Quote from: Barry
I'm guessing that is a Thompson TG585v7 router?
Not sure if those are compatible with DMT or Routerstats, but I would sure like to get a look at the 'bits per tone' graph - it might highlight something interesting.
B.

Hi Barry
You're right that it's a standard Plusnet, recent issue Thompson router (the 585 bit sounds familiar) and as luck would have it I have been running Routerstats for several days now. If you're interested to know, Routerstats worked very easily for me as the Thompson router is listed as one of those that should work 'out of the box' so to speak.
I'm currently at work but I will be sure to post the bits per tone graph when I get home tonight that should show all activity since the resync late last night.
I'm no expert with Routerstats so please forgive my newbie question: Is a screenshot ok or is there some sort of export file that I should post that would give you more detail?
For the record, I have absolutely no idea what the bits per tone graph means but I'd be grateful if you can spot anything that might clarify what's going on.
Many thanks.
Community Veteran
Posts: 3,789
Registered: 08-06-2007

Re: 21CN speed disappointing

This is a 'bits per tone' graph:

It tells you exactly which frequencies on your line are carrying data, and which have been excluded due to interference.  That report is from DMT, but I believe Routerstats can give you a similar report (It really does depend on whether your router is 'fully' supported though)
B.
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: 21CN speed disappointing

this is the one you will get with routerstats but i dont think the speedtouch is able to use the telnet features of routerstats.
i belive DMT works fine with the speedtouch thoe you just need to make sure your get the right version. little more info on the kitz site http://www.kitz.co.uk/routers/DMTv7.htm
ComplexP
Grafter
Posts: 98
Registered: 02-10-2009

Re: 21CN speed disappointing

Looks like I cant view that image from work as the cookies are 'restricted'.
I'm fairly sure I've got the full version of routerstats installed which is configured to work with the TG585. Asbo seems to be suggesting that the bits per tone graph may not be working due to the 585 being a speedtouch model. That would be annoying.
If this is the case I may have to download DMT and post something in a few days.
Thanks both.
PeeGee
Aspiring Pro
Posts: 1,093
Thanks: 49
Fixes: 3
Registered: 05-04-2009

Re: 21CN speed disappointing

Bits graph works fine with the 585 - even running routerstats under opensuse/wine  Smiley I can't get DMT to find the router, though, even using a virtual machine running XP which connects fine  via telnet :-(
I also had weird values (4 x 10^9) for the uplink errors, but they seem to have cleared - I've only been on the trial for 18 days and have had sync speeds of 614/3307 for the last 5 days (a 37% & 55% increase over ADSL), but with atten figures of 37.5/61 and SNR 5/6.5
Subject to the type of noise on your line, I would have thought 6 or 7M was a realistic expectation for the figures you posted.
Despite struggling to get 30k on analogue dial-up, ADSL2 seems pretty reliable for me.
DMT update: It needed the "ping" check disabled to run in usermode under wine  Embarrassed
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.