Kitz Forum
Broadband Related => FTTC and FTTP Issues => Topic started by: ip75 on February 01, 2015, 05:47:05 PM
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Hi all,
This is my first post. I’ve been lurking on here for a while, and I’ve learnt a lot - great site!
I'm hoping for a little advice. I’ve been happy with Sky for ADSL2+ for about a year, and now my cabinet has finally been enabled for FTTC as part of the BDUK scheme. However, I was a little taken aback by the speed estimate from the BT Wholesale checker:
High Low High Low
FTTC Range A (Clean) 46.1 33.1 10 6.6 -- Available
FTTC Range B (Impacted) 39 22.4 10 4.8 -- Available
WBC ADSL 2+ Up to 5 -- 3 to 7.5 Available
WBC ADSL 2+ Annex M Up to 5 Up to 1 3 to 7.5 Available
ADSL Max Up to 4 -- 2.5 to 7 Available
WBC Fixed Rate 2 -- -- Available
Fixed Rate 2 -- -- Available
which to me suggests a fairly long line to the cabinet (7-800m, perhaps?). However, the cabinet I’m connected to is only 200m or so along the road, and I can see by the overhead lines that the route is pretty direct. The line runs 150m overhead to the DP, which is about 50m from the cabinet along a main road. The cable goes underground at that point so technically I don’t know the route it takes, but it seems unlikely it would meander too much.
There are some houses on a small estate right by the cabinet that are served underground, which get a full 80/20 estimate. Those houses also get an “Up to 5” estimate for ADSL2+, so it seems hard to believe that my line is really 7-800m longer. I actually get a stable ADSL sync at 6.5Mbps.
So my question is - is it possible that this estimate is incorrect, and is there any way to check this out prior to ordering the service? I would like to go for an 80/20 service but don’t want to commit to this if I’m really only going to get a maximum of 46Mbps. And yet, with Sky, the minimum term for 40/10 is 18 months, versus 12 months for 80/20, so I don't want to unnecessarily commit to a longer contract if I could really get a faster speed on the shorter contract.
Many thanks in advance for any help!
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Judging by the other estimates for ADSL ..... alongside your VDSL estimate, I would guess that you are not fed via the Cab that's 200mtrs down the road ??
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................. and welcome to the forum. :)
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Thanks!
I agree that that's what the numbers suggest, but it's definitely that cab. There are only 3 in the village, and this one was the last to be enabled. DSL checker for my address says cabinet 6, and it's got a nice clear 6 stencilled on it, and I've had BT engineers out to a couple of faults in the past who have confirmed it.
My feeling is that this could be a database error, but from what I've read these estimates are usually pretty accurate.
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Obviously, I'm not doubting your word, but something doesn't add up if that indeed is your Cab ?? It's as you say, unless the cable takes an inane underground route from Cab to DP, those estimates are way out ??
The only other thing that may be a possibility (especially as you make it clear you live in a rural dwelling), is that the Cab you mention is actually a 'Pillar'. We call these SCP's (Secondary Cross-Connection Point), as opposed to a main Cab, which is called a PCP (Primary Cross-Connection Point).
If this is the case, it would suggest the VDSL DSLAM has been located at the PCP, and not the SCP ?? This is only a guess, and you could confirm otherwise by stating whether a new VDSL Cab has been installed near to (within 50mtrs) of your Cab 6 ??
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Thanks for taking the time to respond! Yes, a fibre cabinet has been installed right next to the cabinet, so I guess it can't be an SCP. It was first installed last summer, and the power was finally connected last Monday. It went live on the DSL checker yesterday.
I'm glad you think something doesn't add up, because I think that points more towards it being a database error, would you agree? I suspect the best course of action is going to be to order a 40/10 service, and then take a look at the line stats to find out what the real attainable sync would be. I will try to get the database corrected if that does turn out to be the problem, because an artificially low estimate would cause problems if I had a fault in future.
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It's very easy to check if you can order FTTC just go to plusnet https://www.plus.net/ (https://www.plus.net/)
and Check what's available where you live, simple as a raspberry pi ;D
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Yes, FTTC is definitely available. I was just questioning whether the speed estimate is actually correct.
Edit: plus.net offers me 33mb, which I assume is based on the same data as the BTw checker.
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Yes, FTTC is definitely available. I was just questioning whether the speed estimate is actually correct.
The estimate is correct you have a choice 40/10 or 80/20 and your Downstream speed is estimated a 46000 kbps it's up you but i would go for 80/20 unlimited if it were my line as all i can get is 31000kbps ;) but will always go for a short contract.
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If ip75's line is only 200mtrs from the PCP ....... then those estimates are far from correct. The FTTC estimate has to be based on the 80/20 product, as it gives a 'clean' number of 46.1Meg ?? At 200mtrs, that is ludicrously short of what is capable !!!
As I keep saying, it all depends on what the true value is from the DSLAM. :)
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I shall sign up for Sky Fibre and report back with stats once it's up and running.
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If ip75's line is only 200mtrs from the PCP ....... then those estimates are far from correct. The FTTC estimate has to be based on the 80/20 product, as it gives a 'clean' number of 46.1Meg ?? At 200mtrs, that is ludicrously short of what is capable !!!
As I keep saying, it all depends on what the true value is from the DSLAM. :)
were you not the one who said on these forums that BT OpenReach will not be swayed or dictated to by the (end-user) findings, only the evil empire can help ip75 ;)
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?? eh ?? Completely lost me there NS ??
The OP in this instance isn't 'dictating' anything, he/she is merely asking if the estimate based on their perception of 'distance to Cab', is realistic ?? I say no, it is not.
Obviously something isn't being reported correctly, be that the 'Guesstimate' from BTw machine, or in-advertent mis-information from the OP ?? :)
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Yes, either the line takes a crazy route underground between the cabinet and the DP (adding at least 500m I reckon), or the estimate is wrong, or there's something else I've missed!
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?? eh ?? Completely lost me there NS ??
The OP in this instance isn't 'dictating' anything, he/she is merely asking if the estimate based on their perception of 'distance to Cab', is realistic ?? I say no, it is not.
Obviously something isn't being reported correctly, be that the 'Guesstimate' from BTw machine, or in-advertent mis-information from the OP ?? :)
BS it's more than likely the data base is wrong if he/she is 200 meters from the PCP cabinet though their perception of the copper/Ali track could be way off as you know only to well.
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If ip75 wanted to, he/she could pm me their post code and I could attempt to confirm the actual route, and total length ? If they trawl back through my postings, they'll see it's all done in the strictest confidence. :)
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That would be fantastic, thank you! PM sent.
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Black Sheep has very kindly confirmed for me that the line route to my cabinet is sensible and appears to be around 220m, so hopefully the line will do significantly better than the estimate. I have now ordered the 40/10 service from Sky with an install date of the 10th, when I'll find out for sure.
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Black Sheep has very kindly confirmed for me that the line route to my cabinet is sensible and appears to be around 220m
Thats good news and Black Sheep is an excellent member even though he gets the odd anti-bt stone thrown at him from time to time he has thick and honorable skin ;D
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Yes, either the line takes a crazy route underground between the cabinet and the DP (adding at least 500m I reckon), or the estimate is wrong, or there's something else I've missed!
A chap in my village has the fibre cab near his front door yet his line goes 400 metre's around to his back door via 3 roads :o
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Black Sheep has very kindly confirmed for me that the line route to my cabinet is sensible and appears to be around 220m
Thats good news and Black Sheep is an excellent member even though he gets the odd anti-bt stone thrown at him from time to time he has thick and honorable skin ;D
Odd ?? Odd, I say !!! It's a full-time job dodging them half-charlies !! ;) :)
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Having mulled this over a little bit, and putting some addresses into the DSL checker, I have a theory, for what it's worth. As I said, I'm on a 220m line to cabinet 6, with a top FTTC estimate of 46. My neighbour is on a different cabinet, cabinet 2, which I reckon is about 800m away. His estimate is 40. So, I wonder if the estimate I'm getting for my address is based on the distance from cabinet 2, despite the fact that I'm really connected to cabinet 6.
Incidentally, I found a house just up the road which is connected to cabinet 2, at a minimum distance of 650m from that cabinet, which has an estimate of the full 80mbps, which also seems wrong, so that's some more evidence that the records around here are not quite right.
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As I mentioned in the PM to you, ip75, the prints* I have vision of were slightly 'hazy' around your DP. There is definitely a cable that heads back to PCP6 from the DP, but there is also another cable that I couldn't pin-point as to what its function was, that connects to the main UG spine cable running along the main road ??
It's a long-shot but not completely unheard of ......I'm wondering if that DP has been 'fed' via two different Cabs in the past ?? You do comment that two different site-engineers have confirmed that you are 'fed' from PCP6 though, so I hope the 'haziness' falls in the positive camp which means you will enjoy pretty much full synch speeds ?
* Unless you are in the Lancs & Cumbria/ Manchester patches, my view of the network and all its joint, ducts, boxes, CP's etc etc .......... is quite limited. I have to access a different on-line system that still give decent info, just not with the ease-of-use or depth, that the local network records afford.
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In other words ...... ^^^^ is my disclaimer. ;) ;D ;D ;D
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Oh, that's interesting - but yes, I've been told a few times before by engineers (when I had a line fault a couple of years ago) that I'm on cab 6. The house I mentioned that had an 80 estimate despite being on cabinet 2 *might* actually be connected to the same DP (it's very close to it), so your theory of a DP fed by two cabinets sounds like a good one.
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Well, I was connected today to Sky's 40/10 service, which went very smoothly - it's a self install, and I already had the VDSL capable Sky router. My ADSL connection dropped, and about 10 minutes later it reconnected with FTTC speeds.
The Sky router shows me the following stats (this is all you can get from it):
Broadband Link Downstream Upstream
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Connection Speed 39998 kbps 9999 kbps
Line Attenuation 11.0 dB 0.0 dB
Noise Margin 33.6 dB 31.31 dB
which looks like it could probably do 80/20 quite easily; plenty of margin there and line attenuation is relatively low, although I'm probably the first person on the cabinet so things might get a little worse as more lines are connected (although I have an idea that there are only around 50-60 lines in the cabinet).
So it looks like there really is some anomaly with the estimate from the FTTC checker in this case!
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Yeah - that looks extremely healthy: that's a lot of spare noise margin, and it'll be interesting to see how that changes as take-up rises. Note that there isn't anyone on http://www.mydslwebstats.co.uk/ with a margin as high as that; people capped at 40Mbps are seeing SNRM values of 18-20dB.
My rule of thumb for what an extra 3dB of noise margin is worth in the downstream direction:
- For speeds around 20Mbps, 3dB is worth 3Mbps
- For speeds around 40Mbps, 3dB is worth 6Mbps
- For speeds of 60Mbps or more, 3dB is worth 11Mbps.
I reckon that makes your attainable speed around 120Mbps. A thoroughly reasonable result for no crosstalk on 200m of copper.
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I guess it's possible that the Sky router calculates the overall margin differently to the Huawei modem, although I think the Sky router also uses a Broadcom chip. I actually find the modem side of the Sky router very good - I got a faster and more stable connection on ADSL than I did with any other router I tried.
I'll keep an eye on the margin as more lines are added. I'm tempted to move up to 80/20 but it's pretty expensive on Sky - I'll wait for the novelty of 40/10 to wear off first....
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Unless you are doing something serious, or have a very big family, I doubt you'll see the need for the increase, beyond the bragging rights.
For some extra comparisons, my new line has an attenuation of 8.2dB on about 100m of copper - but I suspect it is 0.4mm stuff. That currently does 80/20 with attainable levels of 98/32 - but the cabinet is definitely well used, and has been there for 4 years.
My previous line had attenuation of 17dB, which was around 350-400m of copper; it started out easily attaining 80/20 3 years ago, but the attainable gradually dropped to leave us on 78/20 at the end of last year.
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Hmm. So the connection has been fine for the last couple of days. However, I have noticed that when I'm on the phone, the downstream noise margin drops by 1dB, and the upstream noise margin drops by 4dB. Which doesn't cause any kind of problem. However, when I hang up, the upstream margin very briefly drops by a further 14db (so from 31dB before the call to 13dB at the end).
The margins are high so this doesn't cause a problem at all at the moment, but I fear it may do if I was on an 80/20 service.
Does anyone know what kind of fault this could be? Does it sound like an HR fault? The line stays quiet throughout.
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I had something similar with ADSL, that is no longer apparent under FTTC. The consensus was for an intermittent HR fault - and the BT test system even showed it once. The main indication was on the upstream SNRM, but I'd sometimes get impacts on the downstream too - at which point, the internet became unusable, and the modem couldn't always hold sync.
More information from this thread (http://forum.kitz.co.uk/index.php?topic=14937.0), including some graphs from DSLstats.
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Thanks WWWombat, your description in that thread sounds pretty similar to what I'm seeing. I think the first step for me to track this down is to connect directly to the master socket, which is inconveniently located in the loft. Normally, the modem is connected via a run of CAT5 from the data extension sockets on the back of the VDSL faceplate - I certainly need to rule this part of the circuit out first.
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b*cat nods in agreement that you appear to have a latent HR fault in the metallic pathway. :(
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Its either a HR fault, or dodgy nte5 in my view.
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Just noticed today that this has now been amended on the wholesale checker:
High Low High Low
FTTC Range A (Clean) 80 74 20 20 -- Available
FTTC Range B (Impacted) 80 61.9 20 12.2 -- Available
which looks closer to reality. The HR fault (if that's what it is) is still present, and also reproduces via the test socket - I'll keep an eye on it but at the moment it's not causing a problem.