Help with sudden line speed drop

Folks,

Have just spent 1hr talking to chap at BT business broadband support. Basically he says "nothing I
can do". Aaaargh!!


My situation is this:

I have a pretty long line - about 5.5km from the exchange.
Originally I had a 1MB fixed service, I then upgraded to ADSL Max hoping for a bit more speed.
When Max was turned on the line speed fluctuated for the first 10 days then settled at around 3.5
down, 448 up. All was stable for about 4 weeks.

Great! thinks I....


But about a week ago the service disappeared for 3 hours - we had a howling gale that day that may
have had something to do with, but I am not sure. The router reported "No ATM circuit found"
although DSL was up.

When the service resumed the speed was down to 2.2MB and was a bit intermittent.
Its been a week since then and it has stabilised at just over 2MB down, with few drop-outs.

I raised a fault with BT broadband support - an engineer checked the line the other day and said he
couldn't find anything wrong. He measured line speed at the green cabinet in our village and at the
exchange and said the was no appreciable difference.


The broadband support people say there is nothing more they can do - and that the speed I am getting
is normal for my line.

But I want to know:

1. Why the sudden drop in speed? It didn't happen gradually.
2. Is there any way to restore it?


The support people cannot answer these questions - they say the "BT wholesale" control the line
speed and that they do not have access to the data. They cannot tell me why the sudden reduction in
speed.


I could understand it if someone has looked at the line stats, spotted too many errors and reduced
then the speed, but it didn't seem error-ridden to me.


Does anyone have any idea what may have happened?
And how I should proceed?



Thanks in advance - Adam




The current router stats are:

Down speed - 2208
Up speed - 448
Down SNR - 16
Up SNR - 19
Down Attenuation - 57.3
Up Attenuation - 31.5
Down "power" - 16.9
Up power - 11.9

Adam Lipscombe wrote:

> The current router stats are:
>
> Down speed - 2208
> Up speed - 448
> Down SNR - 16
> Up SNR - 19
> Down Attenuation - 57.3
> Up Attenuation - 31.5
> Down "power" - 16.9
> Up power - 11.9

The downstream SNR is your problem. The target SNR was probably raised
during the gale when you could have had multiple resynch attempts in a
short period. I would have another go at BT asking them to reset the
target SNR to say 9 or 6. I know that it is possible to ask an ISP to
increase your target SNR to obtain a more stable line so I see no
reason why it cannot be reduced if your line is stable.

JP

"Adam Lipscombe" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Folks,
>
> Have just spent 1hr talking to chap at BT business broadband support.
> Basically he says "nothing I can do". Aaaargh!!
>
>
> My situation is this:
>
> I have a pretty long line - about 5.5km from the exchange.
> Originally I had a 1MB fixed service, I then upgraded to ADSL Max hoping
> for a bit more speed.
> When Max was turned on the line speed fluctuated for the first 10 days
> then settled at around 3.5 down, 448 up. All was stable for about 4 weeks.
>
> Great! thinks I....
>
>
> But about a week ago the service disappeared for 3 hours - we had a
> howling gale that day that may have had something to do with, but I am not
> sure. The router reported "No ATM circuit found" although DSL was up.
>
> When the service resumed the speed was down to 2.2MB and was a bit
> intermittent.
> Its been a week since then and it has stabilised at just over 2MB down,
> with few drop-outs.
>
> I raised a fault with BT broadband support - an engineer checked the line
> the other day and said he couldn't find anything wrong. He measured line
> speed at the green cabinet in our village and at the exchange and said the
> was no appreciable difference.
>
>
> The broadband support people say there is nothing more they can do - and
> that the speed I am getting is normal for my line.
>
> But I want to know:
>
> 1. Why the sudden drop in speed? It didn't happen gradually.
> 2. Is there any way to restore it?
>
>
> The support people cannot answer these questions - they say the "BT
> wholesale" control the line speed and that they do not have access to the
> data. They cannot tell me why the sudden reduction in speed.
>
>
> I could understand it if someone has looked at the line stats, spotted
> too many errors and reduced then the speed, but it didn't seem
> error-ridden to me.
>
>
> Does anyone have any idea what may have happened?
> And how I should proceed?
>
>
>
> Thanks in advance - Adam

Might be worth getting your ISP to try interleaving at the BT end if its not
already on.
This may help but it will increase latency.


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Many thanks.

Some questions so Can gave a go at them with some knowledge:

For SNR, is a higher figure better, or worse?
(Presumably with attenuation a higher figure is worse?)

What is the "target SNR"?
Can BT reset the SNR? Isn't it a function of the line length and quality etc?



Thanks - Adam


John P wrote:
> Adam Lipscombe wrote:
>
>> The current router stats are:
>>
>> Down speed - 2208
>> Up speed - 448
>> Down SNR - 16
>> Up SNR - 19
>> Down Attenuation - 57.3
>> Up Attenuation - 31.5
>> Down "power" - 16.9
>> Up power - 11.9
>
> The downstream SNR is your problem. The target SNR was probably raised
> during the gale when you could have had multiple resynch attempts in a
> short period. I would have another go at BT asking them to reset the
> target SNR to say 9 or 6. I know that it is possible to ask an ISP to
> increase your target SNR to obtain a more stable line so I see no reason
> why it cannot be reduced if your line is stable.
>
> JP

Adam Lipscombe wrote:
> Many thanks.
>
> Some questions so Can gave a go at them with some knowledge:
>
> For SNR, is a higher figure better, or worse?
> (Presumably with attenuation a higher figure is worse?)
>
> What is the "target SNR"?
> Can BT reset the SNR? Isn't it a function of the line length and
> quality etc?
>

Higher SNR is good for stability but bad for speed. Normally the
exchange/router try to synch at the highest speed which still leaves a
target SNR (usually 6). On problem lines this can be raised by the ISP
so that the line attempts to synch at say 9. Then if line conditions
fluctuate there is more margin to maintain the connection.

JP

"John P" <(E-Mail Removed)> wrote in message
news:4524d532$0$21360$(E-Mail Removed)...
> Adam Lipscombe wrote:
>
>> The current router stats are:
>>
>> Down speed - 2208
>> Up speed - 448
>> Down SNR - 16
>> Up SNR - 19
>> Down Attenuation - 57.3
>> Up Attenuation - 31.5
>> Down "power" - 16.9
>> Up power - 11.9
>
> The downstream SNR is your problem. The target SNR was probably raised
> during the gale when you could have had multiple resynch attempts in a
> short period. I would have another go at BT asking them to reset the
> target SNR to say 9 or 6. I know that it is possible to ask an ISP to
> increase your target SNR to obtain a more stable line so I see no reason
> why it cannot be reduced if your line is stable.
>
> JP

My line was originally considered to poor for broadband (two years ago),
with sky broaband I get between 2mb and 3mb and a 760 upload (great for the
slingbox).

Sky seem to use 6 or 7db as their target for speed, and they dont seem to
have any training process, it just seems to connect at whatever speed gives
it 6db, if you reset the router, when it reconnects, it will connect at the
speed 6 or 7db allows, whatever it is, the least i have had was 300kb when i
hadnt put the filter on upstairs (i was testing), and now with the wall
filter it can go up to 3200.......

I can see the benefits of BT wholesale method of managing adslmax, but
access to a control panel to reset would be useful, but the llu method that
sky use, seems to suit me more.....

Whatever method the llu provider that Eclipse was using, just doesnt work at
all..... After a month of very very poor speeds, i enabled my other line for
broadband and switched over.

Gaz

Adam Lipscombe wrote:

> Does anyone have any idea what may have happened?

As others have already said, a fault was raised with the engineers and
the engineers probably have applied a SNR change and turned
interleaving on your line.

> And how I should proceed?

If your line is now stable, it's been fixed..... If it's still
intermittent then get as much info as possible about when it
disconnects + what is happening at that time, make sure your router is
plugged into the test socket of the master socket and report it as an
intermittent connection again for further investigation.

Regards

William MacLeod

OK thanks,

Interleaving is on, but AFAIK it has always been on.


BT says its "fixed", and indeed its much more stable.
But I have lost nearly 1/2 of the original connection speed.
Is there any way to persuade them to try to restore this?


Thanks -Adam



(E-Mail Removed) wrote:
> Adam Lipscombe wrote:
>
>> Does anyone have any idea what may have happened?
>
> As others have already said, a fault was raised with the engineers and
> the engineers probably have applied a SNR change and turned
> interleaving on your line.
>
>> And how I should proceed?
>
> If your line is now stable, it's been fixed..... If it's still
> intermittent then get as much info as possible about when it
> disconnects + what is happening at that time, make sure your router is
> plugged into the test socket of the master socket and report it as an
> intermittent connection again for further investigation.
>
> Regards
>
> William MacLeod
>