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Standard User brandscill
(committed) Sat 21-Feb-15 11:35:34
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Can fibre negatively impact ADSL?


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Fibre has recently come to my area but I'm not close enough to he cabinet to benefit. I have started to notice though that since its been available my connection has begun to deteriorate somewhat. More drop outs, slower speed and higher ping.

Could this be coincidence or related? I'm still on your standard ADSL Max

Post Office ADSL 4mbps
Administrator MrSaffron
(staff) Sat 21-Feb-15 12:08:58
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Re: Can fibre negatively impact ADSL?


[re: brandscill] [link to this post]
 
Without seeing before and after line stats difficult to say.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User jroadley
(regular) Sat 21-Feb-15 12:44:50
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Re: Can fibre negatively impact ADSL?


[re: brandscill] [link to this post]
 
Got FTTC end of Augst 2014 - where my ADSL2+ speed was 15mb according to the BT ADSL Checker - it has since dropped to 11mb.

I am 77m from the cabinet so get full 80/20 on FTTC

Just my experience.


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Standard User meditator
(fountain of knowledge) Sat 21-Feb-15 12:46:23
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Re: Can fibre negatively impact ADSL?


[re: brandscill] [link to this post]
 
If there are lots of active copper-side FTTC connections running in the same or bundled cables as your own copper-only ADSL one, the total crosstalk and noise impact on your ADSL connection will be higher, since the speeds of adjacent lines will by definition be much higher. This will be incrementally more noticeable on an already long ADSL line. Indeed, surely this is the very thing that even FTTC subscribers are starting to complain about, and the reason for BT introducing the idea of vectoring?

If you live in a fairly densely populated residential area, branscill, then a fair proportion of people in your neighbourhood may very well have upgraded to FTTC. Even if you're not in a heavily-populated place, it could be that further back towards the exchange it's more heavily populated and in that zone adjacent pairs would be subject to increased noise and crosstalk.

I myself know what it's like to be on a long all-copper line and to incur masses of n&c, as well as impulse noise (my line back to the exchange crosses near to an electrified railway line at one point). You could try moving up to ADSL2, which potentially could give you a tad more speed. However, you'd be in the realm of diminishing returns, as your error rates could then worsen and as a result your speed drop again. Certainly, on my own line ADSL2 is of no benefit. Drop-outs could be improved by you adjusting upward the target SNR of your connection, if you've a router with which you can do that. But doing so would cause a drop in your speed.
Standard User eckiedoo
(experienced) Sat 21-Feb-15 13:21:51
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Re: Can fibre negatively impact ADSL?


[re: jroadley] [link to this post]
 
Could you clarify please?

Have you got both ADSL and FTTC/VDSL simultaneously, ie the ADSL was not switched off/removed as the FTTC/VDSL was activated, in August 2014?
Standard User TheEulerID
(member) Sat 21-Feb-15 13:51:55
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Re: Can fibre negatively impact ADSL?


[re: brandscill] [link to this post]
 
I think it's at least possible, although the stories are anecdotal. It was noticable that on my parent's line (on Plusnet ADSL2+) there were a large number of drop-outs which coincided with the local cabinet being enabled (which is about 1km away). After a couple of weeks, the position stabilised, but at the expense of the target SNR margin going from 6dB to 12dB, although attenuation remains about the same. Downstream speed went from about 8-9 mbps to around to 6mbps. Interleaving is now on, which impacts ping time, but I never checked beforehand, so I don't know if it makes much difference. This suggests that there's more noise, possibly impulse noise, as the margin doesn't fluctuate a lot most of the time. That might have explained the line disconnections.

The exchange line length is about 3km. Ironically the exchange is only 1km away, but a 1960s relocation involved a trombone-line line rearrangement, such that the old exchange effectively became a cabinet and a 2km stretch was run to the new exchange doubling back down the route before separating after about 800m and running across some meadows.

It's no big issue for them; they are the epitome of light users. However, I can't see how having an enabled cabinet can improve ADSL speeds in the same bundle and there must be some possibility of adverse effects, ANFP or not.

Personally I think the possibility of running "full-fat" ADSL from some cabinets should be investigated. It would involve running a VULA ADSL2+ service and, of course, would make exchange based LLU impossible on those lines so possibly it might have to be confined to market 1 exchanges. The wholesale service (lets call it GEA-ADSL2+) would have to be priced at a comparable rate to the BTW ADSL services. It would be transparent to customers, although not to ISPs as it would present in the same way as GEA-FTTC and would be an Openreach, not BT Wholesale product. There's a lot of system and interface changes to do, but I think it would be a relatively cheap way of improving ADSL services to a lot of people beyond sensible VDSL range. Something like this is being adopted in New Zealand.

(A cabinet-based ADSL service has been mooted, but this is designed to be frequency profile compatible with exchange-based services which limits its usefulness).
Standard User godsell4
(regular) Sat 21-Feb-15 14:56:25
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Re: Can fibre negatively impact ADSL?


[re: TheEulerID] [link to this post]
 
Even ADSL1 from the Cabinet would give a welcome speed increase to those in Market1 areas, where we are paying more anyway and have been for many years.

PlusNet BBYW1
Standard User TheEulerID
(member) Sat 21-Feb-15 15:11:56
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Re: Can fibre negatively impact ADSL?


[re: godsell4] [link to this post]
 
Indeed, but given that linecards are available for FTTC cabinets that can be configured for pretty near anything in principle, then it might as well be ADSL2+

It seems to me a good way of meeting some of the USC requirements. Even at 4km there ought to be enough speed to stream SD video.
Administrator MrSaffron
(staff) Sat 21-Feb-15 15:34:23
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Re: Can fibre negatively impact ADSL?


[re: TheEulerID] [link to this post]
 
http://www.thinkbroadband.com/news/6654-asdl2-from-s...

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User APTMAN
(learned) Sat 21-Feb-15 16:51:39
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Re: Can fibre negatively impact ADSL?


[re: brandscill] [link to this post]
 
It's funny you say this as that's what I think has been happening to my long ASDL 4.8Kl line, I'm 300M from the new FTTC cab.
I have found out my problems started at the same time as the first two to be connected to FTTC cab and guest what there lines come 300M with mine ADSL line all underground. frown
Since the the cab went live I have had lots of unexplained drop outs re-syncs, loads of FEC,SES, CRC Errors at the test socket even with the modem powered from a battery and all 240V power turned off to house ! .

Technically the FTTC should not interfere with ADSL as it has power masking should ensure that the impact on existing services is minimal.

Use this to monitor your stats.
http://www.s446074245.websitehome.co.uk/index.html

What area are you ?.

Edited by APTMAN (Sat 21-Feb-15 16:54:50)

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