Intermittent WAN usage, too regular for errors.

[Mackey18]

Hi Guys,

I'm having an annoying issue with my Billion 7800DXL router whereby it seems to drop to 0kbps for a very short, regularly. Below are screenshots in order of 2.4g, 5g, Ethernet. All show this pattern of dropping the speed at regular intervals. Of course the DSL doesn't drop when this happens but it's a complete nuisance when streaming or having an internet call, every few seconds their voice cuts out for a second or so. I thought this might be an error to do with SNR, but I don't think it is, my current SNR is 3, and my reasoning is that if it was an error it wouldn't be so consistently intermittent, it would be random. Anyway, and advice is greatly appreciated.

Mike

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[RandomGeeza]

I'm no expert but that looks like REIN.

http://support.zen.co.uk/kb/Knowledgeba ... -and-SHINE

http://support.zen.co.uk/kb/Knowledgeba ... eywords=bt

TBH, an SNR of 3 is a little on the low side for stability, even if you are close to your exchange etc. Most ISP's set a target of 6, whereby speed and stability can balance out.

I have had no end of random drop outs on my line, which is suspected by my ISP to be REIN/SHINE. Unlike yours though it is not looped and repetitive, it is downright random, making its root-cause almost impossible to identify.

If I were you, I would forgo the few MB/ps you have gained with such a low SNR setting and increase it to 6. I would also try using the test socket of your Master socket (UK - BT plug) which will then rule out anything within your property that may be pulsing. It will not however, rule out external sources of interfence. Such as traffic lights, street lighting, other household's electrical goods.

It may be a start and help you to break down to the root-cause.

EDIT: Add info.

[Mackey18]

Thank you very much, I shall have a look into potential electrical interference, we live in a really isolated location so it isn't street lamps, but could be things like my UPS etc. I shall report back. You don't think that the electrical interference could also contribute to an increased line attenuation do you? For some reason it's jumped up by 2db (since the engineer came and changed the loop we were on) impacting speed greatly.

Thanks,
Mike

[RandomGeeza]

I'm not entirely sure, but it sounds probable.

http://compnetworking.about.com/od/netw ... uation.htm

It may also be a fault on the line, which may increase the attenuation, due to signal loss. A fault producing a consistent, repetitive drop out seems possible? Although, I could be wrong.

As mentioned above, increase SNR to 6, and go through the test socket of the Master plug. If it is still doing it, then you have a better case to approach your ISP with and some confidence that it is not an issue on your side of the wiring.

[Tomken]

A bad joint can increase the Attenuation, so it could well be to do with what the BT guy did.

I was also thinking RF interference for this but the majority of equipment that usually cause interference also operate in the 2.4GHz band, so the same problems occurring in the 5GHz puzzled me - although some cordless phones, radar, perimeter sensors and digital satellite operate on the 5GHz band.

If you have an old AM/MW radio that you can wander around your home with, set it to 612KHz and you may be able to find the cause of the interference, but it isn't a 100% method.

If you have this, place it near a LCD screen and you'll hear a noise that will diminish as you move about a quarter of a metre away and it will be similar noises to that which you will be scanning for, but you would be looking for something that is pulsing.

[Mackey18]

A bad joint can increase the Attenuation, so it could well be to do with what the BT guy did.

I was also thinking RF interference for this but the majority of equipment that usually cause interference also operate in the 2.4GHz band, so the same problems occurring in the 5GHz puzzled me - although some cordless phones, radar, perimeter sensors and digital satellite operate on the 5GHz band.

If you have an old AM/MW radio that you can wander around your home with, set it to 612KHz and you may be able to find the cause of the interference, but it isn't a 100% method.

If you have this, place it near a LCD screen and you'll hear a noise that will diminish as you move about a quarter of a metre away and it will be similar noises to that which you will be scanning for, but you would be looking for something that is pulsing.

I shall certainly give the radio trick a go. I do actually have my router very close to my computers which of course have displays etc.

With regards to the increase in attenuation, before the engineer came is was at 80 (the highest she'd ever seen) and she got it down to 75 (more than doubling my speed) by changing the loop from the cabinet to the distribution point. About 3 days after that it went up again to 77 (making a huge difference in terms of speed). I personally thought it could be because I was retraining the line lots over the 3 days whilst i messed with settings, and somehow DLM had a part to do with it, or the other idea I had was that the latency type was fast when she changed the loop, and then it went down to interleaving. Just guessing though. I would really like to be able to get those 2db back as it really does make a huge a difference. I've decided to leave it synced for a week before I retry anything.

Thanks,
Mike

[Tomken]

I'm puzzled as to that level of Attenuation.

Usually anything over 65dB and you'd be lucky to get any sort of ADSL broadband speed and with FTTC your Atten. wouldn't be anywhere near that.

Sometimes when I reboot my router, if the line is noisy, a lower sync. speed can increase the Atten. by 1 - 2 points especially if it drops from ADSL2+ to ADSL, so choosing the best (off peak) time to reboot can alter what you get, but if it's late evening when I reboot the router and the speeds aren't what I would expect/like, I'll switch the router off overnight with all cables disconnected and then fire it back up about 08:30.

This is the equivalent to a power cycle, but for much longer than the usual couple of minutes you would normally leave it disconnected for.

The only time the DLM would kick in would be if you suffered a series disconnects over a short period of time or if you rebooted the router a number of times over a short period and would increase the SNRM in an attempt to stabilize the connection.

I don't know if changing the loop would change you from Fastpath to Interleaving as I thought your ISP would only be able to that from their equipment at the exchange.

I think you will have to contact your ISP to have it changed back to Fastpath and see if that makes any diference, but if you want to leave it switched off overnight to see if that improves your speed - leave it at that for about a week and then request the change if it remains stable, but that pulsing interference is certainly a puzzler.

One other thought although I don't know if it's viable.

If you router is set to all modes - ADSL2+ down to G.dmt, wonder if it could be switching in an attempt to give the best speeds and setting the mode to just G.dmt could improve things.

[Mackey18]

I'm puzzled as to that level of Attenuation.

Usually anything over 65dB and you'd be lucky to get any sort of ADSL broadband speed and with FTTC your Atten. wouldn't be anywhere near that.

Sometimes when I reboot my router, if the line is noisy, a lower sync. speed can increase the Atten. by 1 - 2 points especially if it drops from ADSL2+ to ADSL, so choosing the best (off peak) time to reboot can alter what you get, but if it's late evening when I reboot the router and the speeds aren't what I would expect/like, I'll switch the router off overnight with all cables disconnected and then fire it back up about 08:30.

This is the equivalent to a power cycle, but for much longer than the usual couple of minutes you would normally leave it disconnected for.

The only time the DLM would kick in would be if you suffered a series disconnects over a short period of time or if you rebooted the router a number of times over a short period and would increase the SNRM in an attempt to stabilize the connection.

I don't know if changing the loop would change you from Fastpath to Interleaving as I thought your ISP would only be able to that from their equipment at the exchange.

I think you will have to contact your ISP to have it changed back to Fastpath and see if that makes any diference, but if you want to leave it switched off overnight to see if that improves your speed - leave it at that for about a week and then request the change if it remains stable, but that pulsing interference is certainly a puzzler.

One other thought although I don't know if it's viable.

If you router is set to all modes - ADSL2+ down to G.dmt, wonder if it could be switching in an attempt to give the best speeds and setting the mode to just G.dmt could improve things.

Well to clarify the high attenuation, we live very far from a cabinet which has FTTC. Sadly here in the countryside a cabinet has to serve people a couple of kilometres away! We have a line about 1.5km from the cabinet.

Yea, maybe it is just a batch of increased noise, but it still doesn't quite add up as on the days when I had 75db I synced multiple times and it was incredibly solid, and while the sync rate generally fluctuates a little, the Atten was rock solid stable. On top of that anything less than ADSL 2+ and my sync rate is greatly affected sadly even if the attenuation drops with it, and so I have them disabled, so we can rule out switching. I definitely do think DLM will have kicked in because I was really experimenting over the first couple of days when we got the speed boost from the shorter loop, however if I set the router to automatic SNR (when I had 75db I was pushing it 2db and was impressed with the stability) it's sitting happy on 6. I've adopted what you recommended and will leave it to stabilise for a week to see if it is related to DLM. In terms of the latency type my thought was that after changing the loop it was initially on fast path, but was then reduced to interleaving because of all my disconnects during the first day. But then again, not sure if changing the loop would bump me up to fast path as I'm sure I was on interleaving before the loop change, so you're probably right and it's not related to this issue. Here's just a shot in the dark: what if the DLM, not being able to control the SNR because of the router, aimed to achieve stability by other means which the router interpreted as increased Atten? Just a thought.

As for the issue of the pulsing interference, I'm investigating multiple leads with the help of our electricity monitor. When next there's a bout of interference I shall compare the electricity monitor to the pulses and see if I can identify a device that way.

Thanks for all the help, it's nice to talk to people who know what they're talking about as opposed to BT tech support!
Mike

[Tomken]

Hi Mike - It sounds as though BT have been a bit mean when it comes to installing Fibre cabinets.

The DLM has other means of stabilising a connection and that is by increasing the Depth of Interleaving but you would have to Telnet into the router to find those stats - at least you do with the 7800N.

Basic levels should show Down 32 and 4 for Up and the Down can be incremented in 32s whereas the Up would go 4 - 8 -16 (I think).

This Kitz article gives you an explanation of the line stats you will see in Telnet and the example values for D (interleaver depth) shown of 1 /1 are when it is set to Fast Path although ISPs Interleave their connections for stability but if you have Latency problems when gaming, then your ISP will change this to Fast Path upon request which should improve them.

http://www.kitz.co.uk/adsl/linestats_explanation.htm

The rest of the Kitz article is also worth a read as you can learn a lot from it and while it's getting a bit dated now, it's still educational.

Telnet in Win 7 it isn't default enabled and that is done via Programs and Features/Turn Windows features on or off then scroll down and check the box for Telnet Client.

Then to use Telnet - go Start - type telnet 192.168.1.254 (think that's the Default Gateway for the 7800DXL) and press enter.

You'll get a black command window where you log in as you would your router but pressing enter each after admin and your password.

You then enter the cmd adsl info --stats and for any of the cmds you have to use the space and then those two dashes.

Type logout or quit and press enter to close Telnet.

Entering adsl ? should give you examples of other adsl cmds and I think ? on its own will give you the other categories but as it's been a while since I've used Telnet, they may not be exact but you should be able to find your way around after a bit of experimentation.

Tom.

[evansnp]

Is there any possible chance that you could try another router, as this looks like a fault to me. The line drops are too regular to be interference, in fact, does the line drop at all, as surely this would be in the system logs as a resync?