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[Ammit]

Hi everyone!

I dont' post often but I have a nightmare situation (work for ISP) and wondered if you could give me your thoughts. 

I have a customer 9km from the exchange, I have looked into this incident for a whole 5 months now and it's not ever been resolved. 

They have a 500kbps line and the sync rate is always about 704kbps (good) with a line rate of about 500kbps. They complain constantly of slow speeds and are using a VPN for their home workers to dial in. 
They did used to have a very intermittent connection but we have managed to stabalise it. 

We have looked into EVERYTHING and had numerous BT engineers out to look at this, they have installed new sockets (they previously didn't have an NTE5) and we have rejected it back to BT so many times now that they are saying the customer may not be able to have broadband. 

My boss is adamant this can be "resolved" and i'm adamant it can't.  The distance from the exchange is so far and I feel that they are misusing the line they have got - for something 9km (actual cable length) away from the exchange they are doing pretty well at 704kbps - i check it every day and it never drops. 

What do you think the next steps should be?? All customers at this location (5.88km from exchange straight line distance) are having issues.  Leased lines are about 8k per year, SDSL is not an option.  Load balancing an option maybe??

There are no spare copper pairs here either by the way.

[roseway]

I rather think you're on a hiding to nothing unfortunately. With a line that long, getting a reasonably stable 700 kbps sync rate is good going. I think your boss is being unreasonable. Load balancing would be an option to increase the speed, but if there are no spare copper pairs that would assume that the customer already has another line which could be used for the purpose.

Sorry I can't come up with any more helpful suggestions.

[kitz]

You dont say what the attenuation is - but at around 6km straight line 9km cable length, then they really are pushing the realms of adsl.  So to be getting a consistantish 700kb then they are doing pretty damn well.

Its likely to be doing so well due to being tweaked to the max and new sockets etc. 
Unfortunately on a line like this keep rejecting it to BTw isnt going to do any use.. they obviously have done all they can to improve such a long line..  and it will get to the point were BTw can say - ok theres nothing more we can physically do - therefore if youre not happy, then thats it or the line will have to be classed as incapable.  It wasnt too long ago that BTw said that any lines over 5km wouldnt be able to get adsl.. but its now a case of suck it and see.  If it works then fine.. if it doesnt then they'll do all they can to get at least 256kbps.. otherwise.. the line is classed as too long for adsl.

>> My boss is adamant this can be "resolved"

Im not sure how.. adsl signal deterioates over distance..  other than the customer moving nearer the exchange.

Load balancing a couple of lines is a possibility.. but on such a long line there no guarantee that a new pair would be able to ever attain what the existing line is already getting.
Another option is if the locality has any WiFi providers.. but I guess your boss wouldnt like that later idea too much

[Ammit]

Guys thanks very much for your answers, I'm glad that you've confirmed what I already thought was the case to be honest. 

I have been told the line is very "noisy" although i'm still very vague on what attenuation/SNR and that lot mean to a line.  But basically I can see that the line is running out of steam.  The quote for leased lines (2mb) was about 9k so if they want guaranteed adsl then I guess that's what they are going to have to pay!

Line attenuation is 63.5db downstream and about 35db up.  I think that's quite high am I right?? Noise margin is 7.7db down and 16db up. 

This is a brick wall/head job for me - I have already explained everything, we are still looking for a "resolution".  God help me!! 

[roseway]

That line attenuation may well be understating the truth. 63.5 is the highest figure which most routers will report, even if it's actually a lot more. If I were that customer I would be pleased that you had helped me to get at least a usable connection.

[kitz]

>> Line attenuation is 63.5db downstream and about 35db up.  I think that's quite high am I right??

Very high.  In fact 63.5dB is the maximum figure that many routers will report. 
In reality the attenuation is likely to be much higher.

Have a search on 63.5dB and you should find plenty of references that its to do with the G.992.1 standard (adsl to you and me) which  quotes "The attenuation ranges from 0 to 63.5 dB with 0.5 dB steps."


>> I have been told the line is very "noisy"

Yeah rite!
If that line is constantly holding on to a sync of 700k on a 6dB SNR profile (as would be indicated by the 7.7dB)..  then there isnt any suggestion to me that the line is noisy.  At 5.88km straight line and 9km cable length Its an exceedingly good line to be able to keep the connection.

Approx 6 km (cable length) is said by BT to be the limitation for 1Mbps, so Im really not sure how your boss thinks 9km is going to be able to get anything more.

You could always have a read of BTs SIN no 386 section 2 which states the technical reach limitations which prevents users beyond 6km from getting 1Mbps.  This then goes on to say that beyond that distance Users may be able to get 512 kb..  and that Maxdsl may be able to obtain service at greater distances but it is likely to be at the lower end of the rate adaptive range.
(A line can rate adapt right down to 160 kbps)

It also states in there that prior to Sept 2004 6km was the limitation for adsl.
But since that time they will provide dsl to lines longer than this on a "best it can" service which depends on line length and conditions as I mentioned above.

[rwm32]

A couple of thoughts on VPN and low bandwidth lines:

On our secure VPN there is a constant security traffic overhead, as the black box client does its "are you there? yes I'm here!" song-and-dance routine with the host all the time; not really noticeable on our 6500kbps profile, but obviously it will soak up a much much higher proportion of the available bandwidth on a 700kbps profile.

Our IT people gave us a tech questionnaire before upgrading us from 56k dial-up. As I recall, we had to have at least a 2Mb connection to be considered for the broadband VPN solution.

So I'm not in the least surprised if your customer feels that their VPN speed is very poor, especially if someone in their IT dept promised them a spectacular improvement over 56k.

rwm32

[Ammit]

The customer has just run a speed test for me. 

The speed test shows 47kbps!!!! 47!!??

This MUST be something to do with the VPN, surely!! I have no idea how to proceed with this now, I have asked that they disconnect the VPN in order to run the speed tests, the lady who did the test was in the office not doing it from home so she was not using the VPN.

I am stuck here.....help!? 

[rwm32]

Ummm.  I'm probably being rather slow myself here, but.....

How did your customer manage to run a speed test on the line if she's not at home?

[Ezzer]

Ammit, the longest line I ever managed to get a reliable sync was Approx 9.4km (had to some fiddling to swap to as much avalable 0.63 copper along route to do it) this was a fixed speed 0.5mb circuit.

As stated before most router will not quatifi a figure greater than 63.5db line loss, and that also goes for a woosh test as well. An APtS tester which openreach enginners have will give the actual loss beyond 63.5 (I think that longest line was about 79-80db from memory) From what I can see then the end user is getting a fair service for the fabric of network avalable, and in a better situation than most at that distance.

I do know on one comercial property i've been to on at least 7 occasions because a new isp assures the end user thay can get them dsl, the line is 10.4km and I can get sync for enough seconds to get an 82db reading, nothing would hold sync for more than 15 second if at all.

Depending on the layers a VPN service is set up under, the VPN can create problems in it self regardless of connection (ask any Openreach engineer with a work laptop) Must have taken me 8-12 attempts to log on this morling due to VPN yet with the same router my pc  and mobiles connect first time every time.

I would think your suspisions with VPN is the more likely cause of a problem

[Ammit]

Ummm.  I'm probably being rather slow myself here, but.....

How did your customer manage to run a speed test on the line if she's not at home?

The broadband is in the office, people dial in from home via VPN to work.  What I was saying was nobody was USING the VPN at that point so use wasn't the issue (at least not of people) - however, firewall and exchange are the other things used on this VPN - the speed tests have now gone up to about 113kbps with nobody using them. 

I am really thinking that the background processes might be eating the other 400kbps.

[Ammit]

Line details for two customers on the same premises.

Attenuation: 60db+ loop loss, margin around 9db
Dynamic Line Management profile: set to 9db interleaved (therefore downstream line rate is 500kbps).
Downstream line rate: 500kbps (1/2mbps) (this varies during the day with all lines)
Actual Cable Length: 15km – this is over double what BTw consider a long line.
IP stream connection


Attenuation: 60db+ loop loss, margin around 9db.
Dynamic Line Management profile: set to 6db interleaved
Downstream line rate 750kbps (this varies during the day with all lines)
Actual Cable Length:  15km – this is over double what BTw consider a long line.

[roseway]

To be honest, those figures are a bit hard to believe. I rather suspect that the 15 km line length is an error.

[Ammit]

Well I'd be surprised it was even working but all the same BTw have given us that info.

[kitz]

15km