Slow internet - strange noise margin stats

paddy

paddy

paddy

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24 Aug 2003
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Location
Derbyshire
Apologies for another of these.

My modem has synced at 8mbps, on a good day I get 2mbps, normally 1.5mbps, but when things get busy in the evenings:

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:mad:

Edit: 1:30 pm on a Thursday
1519894052.png


Modem reports this:

modem1.jpg


There is a truck load of bad cable in the house which I need to sort out but
- would that be the reason for upstream noise to be so high?
- is the downstream noise "normal"?
- why the large differential?
 
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At 448 sync the snr is always that high,I would be more worried about the downstream snr 13.6 db is very high with your attenuation you should be at 24meg or very close to it,are you plugged into the master socket(if not do so) if you are think about getting a filterd face plate that would bypass your internal wiring.there Is noise on your line somewhere but extentions and anything other than the master socket is bad for BB
 
I'm connected to the master socket, but the internal wiring to the socket is a mess of crushed/kinked cable - over the coming weeks I plan to shorten everything and replace the face plates with decent ones.

It's good to know I *should* get fast speeds, so I've something to aim for. Thanks
 
Looking at the line attenuation you live right next door to the exchange, the 8128/448 connection suggests you are on ADSL 1 which is "up to 8mb" - not ADSL 2+ which is "up to 24mbps"

What router are you using?
 
Lowest attenuation I've ever seen.

To get speeds like that, even on g.dmt adsl, suggest firmly that your ISP either sucks or is traffic shaping you.

I wonder if your ISP have told you that you are on a 24 Mbps product but actually put you on a BT resold up to 8mbps product.

Noise margin is the amount of noise the modem hears ratioed against the adsl signal. Higher means less noise and more signal. 5-7db would be a typical ISP set margin.

At 8 Mbps you should have much higher margin than that. People with 30db attenuation can get 8 Mbps and their lines would be much much longer than yours.

I suppose it could be misreading the attenuation though. Exchange close to you?

Disconnect all phone equipment and plug in modem to master socket and take readings of noise margins and attenuation again and compare. If you can isolate extensions so that their noise doesn't affect the signal. Maybe try the test socket.
 
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I live opposite the telephone exchange.

Apologies for the confusion though, it appears my exchange is only enabled with "20CN ADSL". With my details entered, the ADSL24 package selector says I can only get up to 8Mbps - so you were right, no ADSL2+ :(

This weekend I'll sort out the phone cabling in the house and follow your advice. I'll let you know how it goes

For information though:
Modem: Netgear DM111 ADSL2+
Router: Linksys WRT54G/GL/GS (firmware: DD-WRT v24-sp1 (07/27/08) micro)
ISP: ADSL24 - Home30 package
 
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Maybe get your ISP to do an SNR reset? Looking at your router aswel you are on a G.DMT mode

You need to be on Multi-mode or ADSL2+ if your router supports it as G.DMT will only give you up to 8mb and obviously it will only hit 24mb if your exchange is 21CN enabled or you are on an LLU package which supports up to 24mb.
 
So we've established he's on an 20CN exchange, he's syncing at full speed for 20CN and has a very healthly SNR yet he's getting very low throughputs especially at peak times???

I'd be first asking the ISP to check the backhaul is not saturated at the exchange - if it's not, then I'd be looking around for another ISP who is not throttling or doesn't have enough capacity.
 
PistolPete said:
I'd be first asking the ISP to check the backhaul is not saturated at the exchange - if it's not, then I'd be looking around for another ISP who is not throttling or doesn't have enough capacity.
Click to expand...

This.

but also..

It sounds like you are on a non LLU line and therefore subject to the restrictions of traffic management and shaping not evident on an LLU line. There's not a whole lot you can do apart from move to a more expensive ISP that doesn't manage data and try and cram as many users onto a limited bandwidth as possible.

It may not be this but knowing the amount of people complaining who are non LLU I would guess that it could be.
 
Reading through my ISPs FAQ it may be a stuck profile at the exchange.

I'll work through the things they suggest and see how I go
 
adsl24 didnt shape/throttle when i was with them last year, it could be the exchange is overloaded, so the isp won't matter, all you can do is speak to adsl24 if the setting changes off their faq don't help.
 
paddy said:
I'm connected to the master socket, but the internal wiring to the socket is a mess of crushed/kinked cable - over the coming weeks I plan to shorten everything and replace the face plates with decent ones.

It's good to know I *should* get fast speeds, so I've something to aim for. Thanks
Click to expand...

Hi there,

When you do this make sure you remove the bell wire. You can read how here: http://www.kitz.co.uk/adsl/socket.htm You just need to leave terminals 2 & 5 connected.

A good faceplate is the ADSLNation XTE-2005 Professional.

I've done all that myself and it helped with the speed.
 
I had this problem when I was with Aquiss and they said it was exchange congestion and there was nothing they could do unless BT upped the bandwidth. So, reluctantly, I had to move my connection to the SKY LLU and couldn't be happier that I did.

I know that's not an option but everything you have posted looks exactly like my issue - exchange congestion.
 
I just checked the exchange and BT is reporting no VP issues, so it's looking even more likely to be an ISP issue.

I would not even bother looking at your cabling - you are syncing at full speed for your ADSL mode with plenty of SNR margin. No amount of fiddling with cabling, removing bell wire or using test sockets will help you as they all fixes for improved sync speed, which in turn increases throughput - you simply can not sync any faster.
 
VP is a virtual path. It's basically the back haul connectivity BT uses to get all the ADSL data in and out of the exchange. If this is congested, all users on every ISP starts getting problems and BT should (eventually) add a bit more capacity.
 
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