Advice on SNR values

Hi,

Although I have a lot of experience as a network / systems tech, I am
not really very conversant with the technical details of ADSL
broadband.

Through reading posts on this and other forums, and by various forays
into the world of google, I have formed the (possibly erroneous)
conclusion that "good" SNR figures should be 16dB or higher.

I have a BT Business ADSL connection, about 5km from the exchange, the
last 100 metres as overhead cable. I get real world speeds of <> 6Mb
downstream and <> 400 Kb upstream, which is fairly stable - except in
high winds!!
However my SNR figures as quoted from the 2wire router are:

Current Noise Margin: 8.0 dB (Downstream) 26.0 dB (Upstream)
Current Attenuation: 11.9 dB (Downstream) 5.0 dB (Upstream)
Current Output Power: 11.7 dBm (Downstream) 12.3 dBm (Upstream)

In light of what I said above about "good" values, would you expect
that I should be able to get a better downstream SNR and therefore a
higher speed? Or given my geographical and connection circumstances do
you think those figures are about right?

I'm more curious and trying to learn, than wanting / needing an
improvement, but I would welcome your expert input.

Oh and I expect to be flamed unmercifully for going with BT, but
changing provider now would be difficult as I run 13 static addresses
with various stuff serving dns, web, mail, voip, ftp and other things
which would be a pain to change.

Thanks very much

Alister.

On Dec 20, 9:49*pm, "Kráftéé" <kraftee@b&e-cottee.me.uk> wrote:
> Alister wrote:
>
> > Current Noise Margin: *8.0 dB (Downstream) 26.0 dB (Upstream)
> > Current Attenuation: * * * * 11.9 dB (Downstream) 5.0 dB (Upstream)
> > Current Output Power: 11.7 dBm (Downstream) 12.3 dBm (Upstream)
>
> > In light of what I said above about "good" values, would you expect
> > that I should be able to get a better downstream SNR and therefore a
> > higher speed? Or given my geographical and connection circumstances
> > do
> > you think those figures are about right?
>
> The equipment in the exchange try to get the service to around 6dB on
> the Downstream, so looking at your figures it does appear to right. *A
> little confused by the Dowstream loop Loss/attenuation being so low,

Are you meaning the correlation between the downstream attenuation
figure and the output power or just the figure in general?

> but that could be a perculiarity of your 2 wire of which I've heard
> nothing but good...

I'm not sure if this was said with your tongue firmly in your cheek!!
Used as I am to working with Cisco ASA's and 2600 routers on leased
lines, I find it a slightly worrying that there seems to be no way to
save the config of the 2wire to tftp or any other method. I have had
one instance where I lost the LAN config completely and had to start
from scratch. But overall it seems to be fairly stable... so far.

Alister

Alister wrote:
> Hi,
>
> Although I have a lot of experience as a network / systems tech, I am
> not really very conversant with the technical details of ADSL
> broadband.
>
> Through reading posts on this and other forums, and by various forays
> into the world of google, I have formed the (possibly erroneous)
> conclusion that "good" SNR figures should be 16dB or higher.
>
> I have a BT Business ADSL connection, about 5km from the exchange, the
> last 100 metres as overhead cable. I get real world speeds of <> 6Mb
> downstream and <> 400 Kb upstream, which is fairly stable - except in
> high winds!!
> However my SNR figures as quoted from the 2wire router are:
>
> Current Noise Margin: 8.0 dB (Downstream) 26.0 dB (Upstream)
> Current Attenuation: 11.9 dB (Downstream) 5.0 dB (Upstream)
> Current Output Power: 11.7 dBm (Downstream) 12.3 dBm (Upstream)
>
> In light of what I said above about "good" values, would you expect
> that I should be able to get a better downstream SNR and therefore a
> higher speed? Or given my geographical and connection circumstances do
> you think those figures are about right?
>
> I'm more curious and trying to learn, than wanting / needing an
> improvement, but I would welcome your expert input.
>
> Oh and I expect to be flamed unmercifully for going with BT, but
> changing provider now would be difficult as I run 13 static addresses
> with various stuff serving dns, web, mail, voip, ftp and other things
> which would be a pain to change.
>
> Thanks very much
>
> Alister.
That's good for the distance, the rate will auto adapt until it reaches
a speed that can be maintained with around a 7 to 9 Db Signal to noise
ratio. For a real world speedtest use something like www.speedtest.net
as the rate the router tells you is only the rate to the local dslam and
not the real world.

Steve h

On Dec 20, 10:05*pm, Stev eH
<StevehkhhSDJvhvbjjxbvvbhnvbhzjdnxzvzhzdshbvnjzvnb vnvjbvbcjbvvvvnmxvzjhjzsdgfgsfghgjsghgsljhglhdjfgh fufgfhzysgfhczgugfvzlvufzvllgfzlyfyvlgbylvdfghvbly rylxybvryvbfbllyxd...@tfif.co.uk>
wrote:
> Alister wrote:
> > Hi,
>
> > Although I have a lot of experience as a network / systems tech, I am
> > not really very conversant with the technical details of ADSL
> > broadband.
>
> > Through reading posts on this and other forums, and by various forays
> > into the world of google, I have formed the (possibly erroneous)
> > conclusion that "good" SNR figures should be 16dB or higher.
>
> > I have a BT Business ADSL connection, about 5km from the exchange, the
> > last 100 metres as overhead cable. I get real world speeds of <> 6Mb
> > downstream and <> 400 Kb upstream, which is fairly stable - except in
> > high winds!!
> > However my SNR figures as quoted from the 2wire router are:
>
> > Current Noise Margin: * * *8.0 dB (Downstream) 26.0 dB (Upstream)
> > Current Attenuation: * * * * * * * 11.9 dB (Downstream) 5..0 dB (Upstream)
> > Current Output Power: * * *11.7 dBm (Downstream) 12.3 dBm (Upstream)
>
> > In light of what I said above about "good" values, would you expect
> > that I should be able to get a better downstream SNR and therefore a
> > higher speed? Or given my geographical and connection circumstances do
> > you think those figures are about right?
>
> > I'm more curious and trying to learn, than wanting / needing an
> > improvement, but I would welcome your expert input.
>
> > Oh and I expect to be flamed unmercifully for going with BT, but
> > changing provider now would be difficult as I run 13 static addresses
> > with various stuff serving dns, web, mail, voip, ftp and other things
> > which would be a pain to change.
>
> > Thanks very much
>
> > Alister.
>
> That's good for the distance, the rate will auto adapt until it reaches
> a speed that can be maintained with around a 7 to 9 Db Signal to noise
> ratio. *For a real world speedtest use something likewww.speedtest.net
> as the rate the router tells you is only the rate to the local dslam and
> not the real world.
>
> Steve h

Hi Steve,

Yep, The figures I quoted are real world - what I actually see on file
transfers and using various speed testers.

The router claims 8Mb down 448Kb up - but it always does, as does
another 2wire which we run at a different site
in the south west. It wouldn't surprise me if it wasn't hardcoded into
the router!!

Alister

"Alister" <(E-Mail Removed)> wrote in message
news:b302c9a7-87cf-41dd-9dfa-(E-Mail Removed)...
On Dec 20, 9:49 pm, "Kráftéé" <kraftee@b&e-cottee.me.uk> wrote:
> Alister wrote:
>
> > Current Noise Margin: 8.0 dB (Downstream) 26.0 dB (Upstream)
> > Current Attenuation: 11.9 dB (Downstream) 5.0 dB (Upstream)
> > Current Output Power: 11.7 dBm (Downstream) 12.3 dBm (Upstream)
>
> > In light of what I said above about "good" values, would you expect
> > that I should be able to get a better downstream SNR and therefore a
> > higher speed? Or given my geographical and connection circumstances
> > do
> > you think those figures are about right?
>
> The equipment in the exchange try to get the service to around 6dB on
> the Downstream, so looking at your figures it does appear to right. A
> little confused by the Dowstream loop Loss/attenuation being so low,

Are you meaning the correlation between the downstream attenuation
figure and the output power or just the figure in general?

> but that could be a perculiarity of your 2 wire of which I've heard
> nothing but good...

I'm not sure if this was said with your tongue firmly in your cheek!!
Used as I am to working with Cisco ASA's and 2600 routers on leased
lines, I find it a slightly worrying that there seems to be no way to
save the config of the 2wire to tftp or any other method. I have had
one instance where I lost the LAN config completely and had to start
from scratch. But overall it seems to be fairly stable... so far.

Alister

-----------------

Others here will suggest that the 2-wire router is good on long and noisy
lines.

However any self-respecting router (e.g Vigor) will have a method of saving
its configuration, and can be configured for remote management over the
internet, except of course you cannot access it to change the PPPoA login &
password if you haven't got these right. By contrast BT (but nobody else)
can in principle access the 2-wire in its factory default condition in order
to upgrade its firmware and configure the PPPoA connection parameters.

--
Graham J

On Dec 21, 9:13*am, "Peter Crosland" <g6...@yahoo.co.uk> wrote:
> > Alister wrote:
> > > Hi,
>
> > > Although I have a lot of experience as a network / systems tech, I am
> > > not really very conversant with the technical details of ADSL
> > > broadband.
>
> > > Through reading posts on this and other forums, and by various forays
> > > into the world of google, I have formed the (possibly erroneous)
> > > conclusion that "good" SNR figures should be 16dB or higher.
>
> > > I have a BT Business ADSL connection, about 5km from the exchange, the
> > > last 100 metres as overhead cable. I get real world speeds of <> 6Mb
> > > downstream and <> 400 Kb upstream, which is fairly stable - except in
> > > high winds!!
> > > However my SNR figures as quoted from the 2wire router are:
>
> > > Current Noise Margin: 8.0 dB (Downstream) 26.0 dB (Upstream)
> > > Current Attenuation: 11.9 dB (Downstream) 5.0 dB (Upstream)
> > > Current Output Power: 11.7 dBm (Downstream) 12.3 dBm (Upstream)
>
> > > In light of what I said above about "good" values, would you expect
> > > that I should be able to get a better downstream SNR and therefore a
> > > higher speed? Or given my geographical and connection circumstances do
> > > you think those figures are about right?
>
> > > I'm more curious and trying to learn, than wanting / needing an
> > > improvement, but I would welcome your expert input.
>
> > > Oh and I expect to be flamed unmercifully for going with BT, but
> > > changing provider now would be difficult as I run 13 static addresses
> > > with various stuff serving dns, web, mail, voip, ftp and other things
> > > which would be a pain to change.
>
> > > Thanks very much
>
> > > Alister.
>
> > That's good for the distance, the rate will auto adapt until it reaches
> > a speed that can be maintained with around a 7 to 9 Db Signal to noise
> > ratio. For a real world speedtest use something likewww.speedtest.net
> > as the rate the router tells you is only the rate to the local dslam and
> > not the real world.
>
> > Steve h
>
> Hi Steve,
>
> Yep, The figures I quoted are real world - what I actually see on file
> transfers and using various speed testers.
>
> The router claims 8Mb down 448Kb up *- but it always does, as does
> another 2wire which we run at a different site
> in the south west. It wouldn't surprise me if it wasn't hardcoded into
> the router!!
>
> The 8128 and 448 are the maximum the circuit is allowed to run at and is
> retrieved from the DSLAM. It has nothing to do with the actual performance
> of the particular installation. You need to look at the figures within the
> Management and Diagnostic Console of the 2Wire to see what is actually
> happening. This can be accessed by putting the router IP address followedby
> /mdc into your browser for example 192.168.1.258/mdc when the 2Wire is set
> to as default. Once in the MDC click on the DSL Diagnostics link under the
> Troubleshooting section.
>
> HTH
>
> Peter Crosland

Hi Peter,

Those figures are the ones I get from the mdc statistics page (pasted
below) but they are exactly the same on two other BT 2wire routers in
different parts of the country which I administer, so either I am
extraordinarily lucky or the figures are hard wired into the gui!!

Current Rate: 8128 kbs 448 kbs
Max Rate: 8964 kbs 1096 kbs

Alister

On Dec 21, 6:50*pm, "Peter Crosland" <g6...@yahoo.co.uk> wrote:
> :
>
>
>
> > > Alister wrote:
> > > > Hi,
>
> > > > Although I have a lot of experience as a network / systems tech, I am
> > > > not really very conversant with the technical details of ADSL
> > > > broadband.
>
> > > > Through reading posts on this and other forums, and by various forays
> > > > into the world of google, I have formed the (possibly erroneous)
> > > > conclusion that "good" SNR figures should be 16dB or higher.
>
> > > > I have a BT Business ADSL connection, about 5km from the exchange, the
> > > > last 100 metres as overhead cable. I get real world speeds of <> 6Mb
> > > > downstream and <> 400 Kb upstream, which is fairly stable - except in
> > > > high winds!!
> > > > However my SNR figures as quoted from the 2wire router are:
>
> > > > Current Noise Margin: 8.0 dB (Downstream) 26.0 dB (Upstream)
> > > > Current Attenuation: 11.9 dB (Downstream) 5.0 dB (Upstream)
> > > > Current Output Power: 11.7 dBm (Downstream) 12.3 dBm (Upstream)
>
> > > > In light of what I said above about "good" values, would you expect
> > > > that I should be able to get a better downstream SNR and therefore a
> > > > higher speed? Or given my geographical and connection circumstancesdo
> > > > you think those figures are about right?
>
> > > > I'm more curious and trying to learn, than wanting / needing an
> > > > improvement, but I would welcome your expert input.
>
> > > > Oh and I expect to be flamed unmercifully for going with BT, but
> > > > changing provider now would be difficult as I run 13 static addresses
> > > > with various stuff serving dns, web, mail, voip, ftp and other things
> > > > which would be a pain to change.
>
> > > > Thanks very much
>
> > > > Alister.
>
> > > That's good for the distance, the rate will auto adapt until it reaches
> > > a speed that can be maintained with around a 7 to 9 Db Signal to noise
> > > ratio. For a real world speedtest use something likewww.speedtest.net
> > > as the rate the router tells you is only the rate to the local dslam and
> > > not the real world.
>
> > > Steve h
>
> > Hi Steve,
>
> > Yep, The figures I quoted are real world - what I actually see on file
> > transfers and using various speed testers.
>
> > The router claims 8Mb down 448Kb up - but it always does, as does
> > another 2wire which we run at a different site
> > in the south west. It wouldn't surprise me if it wasn't hardcoded into
> > the router!!
>
> > The 8128 and 448 are the maximum the circuit is allowed to run at and is
> > retrieved from the DSLAM. It has nothing to do with the actual performance
> > of the particular installation. You need to look at the figures within the
> > Management and Diagnostic Console of the 2Wire to see what is actually
> > happening. This can be accessed by putting the router IP address followed
> > by
> > /mdc into your browser for example 192.168.1.258/mdc when the 2Wire is set
> > to as default. Once in the MDC click on the DSL Diagnostics link under the
> > Troubleshooting section.
>
> > HTH
>
> > Peter Crosland
>
> Hi Peter,
>
> Those figures are the ones I get from the mdc statistics page (pasted
> below) but they are exactly the same on two other BT 2wire routers in
> different parts of the country which I administer, so either I am
> extraordinarily lucky or the figures are hard wired into the gui!!
>
> Current Rate: *8128 kbs *448 kbs
> Max Rate: 8964 kbs 1096 kbs
>
> What ISP are you using? Those figures are highter than the BT DSL MAX
> product supports.
>
> Peter Crosland

That's what makes me think there is some fudge factor involved :-)

My ISP is BT Business on a non-LLU exchange.

Alister

On Dec 21, 9:04*pm, "Peter Crosland" <g6...@yahoo.co.uk> wrote:
> > > > Alister wrote:
> > > > > Hi,
>
> > > > > Although I have a lot of experience as a network / systems tech, I
> > > > > am
> > > > > not really very conversant with the technical details of ADSL
> > > > > broadband.
>
> > > > > Through reading posts on this and other forums, and by various
> > > > > forays
> > > > > into the world of google, I have formed the (possibly erroneous)
> > > > > conclusion that "good" SNR figures should be 16dB or higher.
>
> > > > > I have a BT Business ADSL connection, about 5km from the exchange,
> > > > > the
> > > > > last 100 metres as overhead cable. I get real world speeds of <> 6Mb
> > > > > downstream and <> 400 Kb upstream, which is fairly stable - except
> > > > > in
> > > > > high winds!!
> > > > > However my SNR figures as quoted from the 2wire router are:
>
> > > > > Current Noise Margin: 8.0 dB (Downstream) 26.0 dB (Upstream)
> > > > > Current Attenuation: 11.9 dB (Downstream) 5.0 dB (Upstream)
> > > > > Current Output Power: 11.7 dBm (Downstream) 12.3 dBm (Upstream)
>
> > > > > In light of what I said above about "good" values, would you expect
> > > > > that I should be able to get a better downstream SNR and therefore a
> > > > > higher speed? Or given my geographical and connection circumstances
> > > > > do
> > > > > you think those figures are about right?
>
> > > > > I'm more curious and trying to learn, than wanting / needing an
> > > > > improvement, but I would welcome your expert input.
>
> > > > > Oh and I expect to be flamed unmercifully for going with BT, but
> > > > > changing provider now would be difficult as I run 13 static
> > > > > addresses
> > > > > with various stuff serving dns, web, mail, voip, ftp and other
> > > > > things
> > > > > which would be a pain to change.
>
> > > > > Thanks very much
>
> > > > > Alister.
>
> > > > That's good for the distance, the rate will auto adapt until it
> > > > reaches
> > > > a speed that can be maintained with around a 7 to 9 Db Signal to noise
> > > > ratio. For a real world speedtest use something likewww.speedtest.net
> > > > as the rate the router tells you is only the rate to the local dslam
> > > > and
> > > > not the real world.
>
> > > > Steve h
>
> > > Hi Steve,
>
> > > Yep, The figures I quoted are real world - what I actually see on file
> > > transfers and using various speed testers.
>
> > > The router claims 8Mb down 448Kb up - but it always does, as does
> > > another 2wire which we run at a different site
> > > in the south west. It wouldn't surprise me if it wasn't hardcoded into
> > > the router!!
>
> > > The 8128 and 448 are the maximum the circuit is allowed to run at andis
> > > retrieved from the DSLAM. It has nothing to do with the actual
> > > performance
> > > of the particular installation. You need to look at the figures within
> > > the
> > > Management and Diagnostic Console of the 2Wire to see what is actually
> > > happening. This can be accessed by putting the router IP address
> > > followed
> > > by
> > > /mdc into your browser for example 192.168.1.258/mdc when the 2Wire is
> > > set
> > > to as default. Once in the MDC click on the DSL Diagnostics link under
> > > the
> > > Troubleshooting section.
>
> > > HTH
>
> > > Peter Crosland
>
> > Hi Peter,
>
> > Those figures are the ones I get from the mdc statistics page (pasted
> > below) but they are exactly the same on two other BT 2wire routers in
> > different parts of the country which I administer, so either I am
> > extraordinarily lucky or the figures are hard wired into the gui!!
>
> > Current Rate: 8128 kbs 448 kbs
> > Max Rate: 8964 kbs 1096 kbs
>
> > What ISP are you using? Those figures are highter than the BT DSL MAX
> > product supports.
>
> > Peter Crosland
>
> That's what makes me think there is some fudge factor involved :-)
>
> My ISP is BT Business on a non-LLU exchange.
>
> Very odd! It would be interesting to know the version number of the hardware
> and firmware. Also it would be interesting to see what the training history
> shows. Could you post that so I could see the other values. The reason I ask
> is I have installed a number of these and never encountered the results you
> have. Having said that BT have introduced version 6 firmware that I have not
> seen. Just curious to to know what is happening! It could be that BT are
> thinking ahead for 21CN and ADSL2+. This page might interest you
>
> http://bt2700hgv.tripod.com/ir100270...ad%20about%20t...
> which gives a lot of information.
>
> Peter Crosland

Hi Peter,

Thanks for that link, interesting stuff!

My current training history is viewable here:

http://btstats.pickwth.com/bt2wire/image1.jpg

and the firmware / hardware version here:

http://btstats.pickwth.com/bt2wire/image2.jpg

See what you think.

Alister

>> > Alister wrote:

> Current Rate: 8128 kbs 448 kbs
> Max Rate: 8964 kbs 1096 kbs

Peter Crosland wrote:

> What ISP are you using? Those figures are highter than the BT DSL MAX
> product supports.

I think what those figures mean is that he's syncing at full BT speed, and
if BT didn't limit connections to those speeds, he would be syncing at the
second set of figures [ie it's extrapolating from the noise margin how much
faster it could go].

--
<http://ale.cx/> (AIM:troffasky) ((E-Mail Removed))
09:03:24 up 17 days, 11:16, 1 user, load average: 0.10, 0.06, 0.06
They call me titless because I have no tits