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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

ADSL speed low, SNR bad but speedtest report OK?



 
 
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  #1  
Old November 5th 12, 01:40 PM posted to uk.telecom.broadband
jkn
external usenet poster
 
Posts: 21
Default ADSL speed low, SNR bad but speedtest report OK?

Hi there
a general sort of question about which line of enquiry to
follow...

A month or so ago our domestic ADSL broadband connection went down. My
ISP (Plusnet) started to get the line investigated with BT (I know
that they are part of the same company); however the connection
started working agian before they got too far with this. However, it's
never been quite the same since ... the perceived speed generally
seems both slow and very variable. I am trying to find out the best
way to get this looked at.

If I look at my Router(*) stats the download and upload speeds look
about what I'd expect ... in the ballpark of 5Mb and 0.5Mbps
respectively. The various speedtesters give the same sort of figure.

However the SNR is being reported as 5 or 6dB - ugh!

I am going to capture the stats over a period of 12 hours or so and
pass them on to my ISP as 'ammunition' re. getting the line checked
once again. But I'm a bit puzzled ... does it make sense that the
speed testers give a good result but the SNR is so bad and the
perceived speed is much poorer than that?

Thanks for any comments

J^n

(*) a Draytek 2820n. In fairness I should report that I also re-
flashed the firmware when we had the initial problems. Here's hoping
that hasn't caused the issue...
  #2  
Old November 5th 12, 02:49 PM posted to uk.telecom.broadband
Graham J
external usenet poster
 
Posts: 620
Default ADSL speed low, SNR bad but speedtest report OK?

jkn wrote:
Hi there
a general sort of question about which line of enquiry to
follow...

A month or so ago our domestic ADSL broadband connection went down. My
ISP (Plusnet) started to get the line investigated with BT (I know
that they are part of the same company); however the connection
started working agian before they got too far with this. However, it's
never been quite the same since ... the perceived speed generally
seems both slow and very variable. I am trying to find out the best
way to get this looked at.

If I look at my Router(*) stats the download and upload speeds look
about what I'd expect ... in the ballpark of 5Mb and 0.5Mbps
respectively. The various speedtesters give the same sort of figure.

However the SNR is being reported as 5 or 6dB - ugh!

I am going to capture the stats over a period of 12 hours or so and
pass them on to my ISP as 'ammunition' re. getting the line checked
once again. But I'm a bit puzzled ... does it make sense that the
speed testers give a good result but the SNR is so bad and the
perceived speed is much poorer than that?

Thanks for any comments

J^n

(*) a Draytek 2820n. In fairness I should report that I also re-
flashed the firmware when we had the initial problems. Here's hoping
that hasn't caused the issue...

5 or 6 dB SNR margin on a Draytek 2820 is absolutely ideal. For an "up
to 8Mbits/sec" service the default SNR margin is 6dB.

A higher margin would indicate a varying noise level on the line so the
router increases the noise margin and reduces the speed in order to
maintain reliability.

On some 21CN circuits (those where the maximum speed is greater than 8
Mbits/sec) the SNR margin may in some circumstances (usually a quiet
line and a short distance to the exchange) show less than 6 dB.

The key parameter in your case is probably the BRAS profile. This is a
second stage speed limit imposed by the BT exchange equipment in
response to intermittent connections. Any unexpected connection failure
could reduce the BRAS profile; which will likely not increase again for
several days.

Use Routerstats to monitor your router continuously over a period of
many days. During this time, run several different speed test
(www.speedtest.net, www.mybroadbandspeed.co.uk, and the like) at
different times of day and record what they report.

Tell us what you see.

--
Graham J

  #3  
Old November 5th 12, 03:23 PM posted to uk.telecom.broadband
jkn
external usenet poster
 
Posts: 21
Default ADSL speed low, SNR bad but speedtest report OK?

Hi Graham
Thans for your very interesting reply:


5 or 6 dB SNR margin on a Draytek 2820 is absolutely ideal. For an "up
to 8Mbits/sec" service the default SNR margin is 6dB.

A higher margin would indicate a varying noise level on the line so the
router increases the noise margin and reduces the speed in order to
maintain reliability.


Oh, I didn't know this ... thanks.


On some 21CN circuits (those where the maximum speed is greater than 8
Mbits/sec) the SNR margin may in some circumstances (usually a quiet
line and a short distance to the exchange) show less than 6 dB.

The key parameter in your case is probably the BRAS profile. *This is a
second stage speed limit imposed by the BT exchange equipment in
response to intermittent connections. *Any unexpected connection failure
could reduce the BRAS profile; which will likely not increase again for
several days.


OK, thanks for the info. It's been a few weeks since we got
reconnected, though...


Use Routerstats to monitor your router continuously over a period of
many days. *During this time, run several different speed test
(www.speedtest.net,www.mybroadbandspeed.co.uk, and the like) at
different times of day and record what they report.

In fact I have been trying to get Routerstats running but it doesn't
seem to have the Draytek router as standard, and I have been having
trouble configuring it for this router. That was why I was going to
run a command-line script to collect the info via telnet/ssh. Any
pointers to getting RouterStats running with the Draytek?

Cheers
J^n
  #4  
Old November 5th 12, 05:22 PM posted to uk.telecom.broadband
Graham J
external usenet poster
 
Posts: 620
Default ADSL speed low, SNR bad but speedtest report OK?



In fact I have been trying to get Routerstats running but it doesn't
seem to have the Draytek router as standard, and I have been having
trouble configuring it for this router. That was why I was going to
run a command-line script to collect the info via telnet/ssh. Any
pointers to getting RouterStats running with the Draytek?



In my experience it works "out of the box". I've used "routerstats
Lite" v6.9. There is probably a more modern version

Setup:
Router: select Draytek 2820n
URL: the local IP address of your router
Login: your username and password

Everything else as you choose.

--
Graham J






  #5  
Old November 5th 12, 05:23 PM posted to uk.telecom.broadband
Graham J
external usenet poster
 
Posts: 620
Default ADSL speed low, SNR bad but speedtest report OK?

[snip]

OK, thanks for the info. It's been a few weeks since we got
reconnected, though...


that not the same as how long the connection has been up. The router
will tell you ...

--
Graham J


  #6  
Old November 5th 12, 06:54 PM posted to uk.telecom.broadband
Invalid
external usenet poster
 
Posts: 154
Default ADSL speed low, SNR bad but speedtest report OK?

In message
, jkn
writes
Hi there
a general sort of question about which line of enquiry to
follow...

A month or so ago our domestic ADSL broadband connection went down. My
ISP (Plusnet) started to get the line investigated with BT (I know
that they are part of the same company); however the connection
started working agian before they got too far with this. However, it's
never been quite the same since ... the perceived speed generally
seems both slow and very variable. I am trying to find out the best
way to get this looked at.

If I look at my Router(*) stats the download and upload speeds look
about what I'd expect ... in the ballpark of 5Mb and 0.5Mbps
respectively. The various speedtesters give the same sort of figure.

However the SNR is being reported as 5 or 6dB - ugh!

I am going to capture the stats over a period of 12 hours or so and
pass them on to my ISP as 'ammunition' re. getting the line checked
once again. But I'm a bit puzzled ... does it make sense that the
speed testers give a good result but the SNR is so bad and the
perceived speed is much poorer than that?

Thanks for any comments

J^n

(*) a Draytek 2820n. In fairness I should report that I also re-
flashed the firmware when we had the initial problems. Here's hoping
that hasn't caused the issue...


You BRAS profile is available from Plusnet's Member Centre/Connection
Settings/High Speed Broadband

The current line speed should be the same as your BRAS figure. If you
click on "find out more about sync speed" and scroll down you will find
a table giving the expected relationship between your router's sync
speed and the BRAS profile. based on your "ballpark of 5M" you will
probably be either

Sync Speed BRAS
4544 - 5119kb/s 4000 (up to 4Mb/s)
5120 - 5695kb/s 4500 (up to 4.5Mb/s)

However if the speed testers are all showing about the same (5M), then
one possibility is that the DNS processes that resolve IP addresses are
causing the perceived slowness.

You might want to check which DNS servers the router is using, and
possibly flush the DNS cache on your PC - if there is a bad entry or two
in there, it could slow down browsing.

run ipconfig/flushdns from a command prompt.


--
Invalid
  #7  
Old November 5th 12, 08:15 PM posted to uk.telecom.broadband
jkn
external usenet poster
 
Posts: 21
Default ADSL speed low, SNR bad but speedtest report OK?

Hi Graeme

In my experience it works "out of the box". *I've used *"routerstats
Lite" v6.9. *There is probably a more modern version

Setup:
Router: select Draytek 2820n
URL: the local IP address of your router
Login: your username and password


I think the more recent Draytek firmware I am using has changed
something ... I'm getting an error 'The URL to the stats page is
incorrect' (even after I've set up the correct IP address).

I'm looking into this further.

Thanks
Jon N
  #8  
Old November 5th 12, 08:20 PM posted to uk.telecom.broadband
jkn
external usenet poster
 
Posts: 21
Default ADSL speed low, SNR bad but speedtest report OK?

Hi there


You BRAS profile is available from Plusnet's Member Centre/Connection
Settings/High Speed Broadband

The current line speed should be the same as your BRAS figure. If you
click on "find out more about sync speed" and scroll down you will find
a table giving the expected relationship between your router's sync
speed and the BRAS profile. based on your "ballpark of 5M" you will
probably be either

Sync Speed * * * * * * *BRAS
4544 - 5119kb/s 4000 (up to 4Mb/s)
5120 - 5695kb/s 4500 (up to 4.5Mb/s)


Thanks for this info. The reported line speed (5.1Mb/s) does indeed
match the sync speed reported.


However if the speed testers are all showing about the same (5M), then
one possibility is that the DNS processes that resolve IP addresses are
causing the perceived slowness.

You might want to check which DNS servers the router is using, and
possibly flush the DNS cache on your PC - if there is a bad entry or two
in there, it could slow down browsing.

run ipconfig/flushdns from a command prompt.


Thanks - I did start to wonder about this myself. My Router has the
correct DNS servers and I have tried flushing the caches in the method
appropriate to the OS (I run a mixture of Linux & Windows). We'll see
if this makes a difference. But I do see a lot of eg. 'waiting for
www.google.com' or 'transferring data from aaa.bbb.ccc' (where
aaa.bbb.ccc is a resolved URL) when looking at eg. an eBay page, so
I'm not sure it's that.

Cheers
J^n
  #9  
Old November 5th 12, 08:43 PM posted to uk.telecom.broadband
Graham J
external usenet poster
 
Posts: 620
Default ADSL speed low, SNR bad but speedtest report OK?

jkn wrote:
Hi Graeme

In my experience it works "out of the box". I've used "routerstats
Lite" v6.9. There is probably a more modern version

Setup:
Router: select Draytek 2820n
URL: the local IP address of your router
Login: your username and password


I think the more recent Draytek firmware I am using has changed
something ... I'm getting an error 'The URL to the stats page is
incorrect' (even after I've set up the correct IP address).

I'm looking into this further.


Interesting. I look after serveral of these routers - all slightly
different variants, so over the next couple of days I will test them.

--
Graham J


  #10  
Old November 5th 12, 10:25 PM posted to uk.telecom.broadband
The Natural Philosopher
external usenet poster
 
Posts: 2,728
Default ADSL speed low, SNR bad but speedtest report OK?

On 05/11/12 20:20, jkn wrote:
Hi there


You BRAS profile is available from Plusnet's Member Centre/Connection
Settings/High Speed Broadband

The current line speed should be the same as your BRAS figure. If you
click on "find out more about sync speed" and scroll down you will find
a table giving the expected relationship between your router's sync
speed and the BRAS profile. based on your "ballpark of 5M" you will
probably be either

Sync Speed BRAS
4544 - 5119kb/s 4000 (up to 4Mb/s)
5120 - 5695kb/s 4500 (up to 4.5Mb/s)


Thanks for this info. The reported line speed (5.1Mb/s) does indeed
match the sync speed reported.


However if the speed testers are all showing about the same (5M), then
one possibility is that the DNS processes that resolve IP addresses are
causing the perceived slowness.

You might want to check which DNS servers the router is using, and
possibly flush the DNS cache on your PC - if there is a bad entry or two
in there, it could slow down browsing.

run ipconfig/flushdns from a command prompt.


Thanks - I did start to wonder about this myself. My Router has the
correct DNS servers and I have tried flushing the caches in the method
appropriate to the OS (I run a mixture of Linux & Windows). We'll see
if this makes a difference. But I do see a lot of eg. 'waiting for
www.google.com' or 'transferring data from aaa.bbb.ccc' (where
aaa.bbb.ccc is a resolved URL) when looking at eg. an eBay page, so
I'm not sure it's that.


Many US links are down/congested at the moment - one assumes Sandy is
the reason.

run speed test on UK speed test sites to exonerate your local loop and
BTs backhaul first


Cheers
J^n



--
Ineptocracy

(in-ep-toc'-ra-cy) - a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

 




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