Half the sync I should have

Hi all, first post here. I'll try and keep this post short despite the length of the on-going issue.

My area can only get around 5Mbps on LLU (Even less on BT Wholesale ISP's due to a very high training target SNR), but this doesn't add up because I've seen people getting ~14Mbps with the same attenuation (~38dB) as me on ADSL2+, and many many people getting full 8Mbps sync with the same attentuation on ADSL2.

On top of this, my line works how I'd expect it to every time there is a power-cut. (UPS ) It even lasts for 10 minutes after a power-cut, at which point suddenly the SNR plummets until Sync is lost. It then re-syncs and I'm back to my laggy 4meg of throughput.

BT point-blank denied any issues until recently when a Engineer confirmed the line gives several more megabips at the nearest CAB. However they have still yet to do fix the source of this problem.

My full router stats are posted below, and i'm hoping some of you can help finally solve this. I have a portable AM radio here if that can help at all?

Power-Cut Performance
[IMG]http://speed.io/pics/2179/0434/speed.io.png[/img]
Normal Performance
[IMG]http://speed.io/pics/2327/3185/speed.io.png[/img]

Text

1 23 45 67 89 1011 1213 1415 1617 1819 2021 2223 2425 2627 2829 3031 3233 3435 3637 3839 4041 4243 4445 4647 4849 5051 5253 5455 5657 5859 6061 6263 6465 6667 68

ADSL driver and PHY status Status: ShowtimeRetrain Reason: 1Channel: INTR, Upstream rate = 768 Kbps, Downstream rate = 5024 Kbps Link Power State: L0Mode:                   G.DMT Channel:                InterleaveTrellis:                ON Line Status:            No DefectTraining Status:        Showtime                 Down            UpSNR (dB):       6.9             14.0 Attn(dB):       38.0            25.0Pwr(dBm):       19.8            9.4 Max(Kbps):      5696            1216Rate (Kbps):    5024            768                         G.dmt framingK:              158(0)          25 R:              16              16S:              1               8 D:              64              8                        ADSL2 framing MSGc:           51              68B:              58              23 M:              4               8T:              3               1 R:              12              16S:              1.5145          7.7037 L:              1310            216D:              64              8                         CountersSF:             305618          305622 SFErr:          0               0RS:             20782090                2596784 RSCorr:         2112185         0RSUnCorr:       0               0  HEC:            0               0 OCD:            0               0LCD:            0               0 Total Cells:    61562444                0Data Cells:     2100432         0 Drop Cells:     0Bit Errors:     0               0  ES:             49              1 SES:            8               0UAS:            7412            30 AS:             5196  INP:            2.34            2.37PER:            16.18           17.81 delay:          24.23           15.40OR:             28.17           33.23  Bitswap:        0               0  Total time = 1 days 14 hours 3 min 23 sec SF  = 328973CRC = 1325 LOS = 8LOF = 72 ES  = 49Latest 1 day time = 14 hours 3 min 23 sec SF  = 328973CRC = 1325 LOS = 5LOF = 45 ES  = 5

I'm not entirely sure what your question is.

You say that:
1. your area usually gets ~5Mbps on LLU.
2. 38dB gives ~14Mbps on ADSL2+
3. 38dB gives 8Mbps on ADSL 2

Your line is using ADSL1 as per this:
Mode: G.DMT

And you are in synch at just a shade under 5Mbps (using old fashioned/corrrect 1Mb = 1024Kb):
Rate (Kbps): 5024


So what actually is the problem?

Maybe I missed the point?

My sync is MUCH higher during and after a powercut, as well as being MUCH higher from the nearest CAB. The last part of my loop loses me over 3Megabips as confirmed by BT. Yet no solution is in-sight.

I doubt that "38dB gives ~14Mbps on ADSL2+"; more like 10 Mbps.

But you are on ADSL1 anyway.

I am refering to stats I've seen people post on another DSL-related site, one person clearly was getting 14Mbps on Be There with a SNR of around 3dB on a 36-39dB line. Do I have to find the exact post just to satisfy you?

The graph on Wikipedia also shows ~12Mbps for ADSL2+ at 37-38dB.

Edited by Opti (Sun 16-Aug-09 00:22:43)

In reply to a post by Opti:

My sync is MUCH higher during and after a powercut, as well as being MUCH higher from the nearest CAB. The last part of my loop loses me over 3Megabips as confirmed by BT. Yet no solution is in-sight.

In perfect conditions 38dB attenuation should give about 7Mbps.

Interesting about the power cut scenario. All I can suggest is that after the power cut a lot of electrical equipment doesn't come back into life until someone switches it on - so less background noise.

How long is the loop to your nearest cab?
Has the engineer tried switching you to a different pair in a different bundle from that cab (if possible)?
What kind of area is it? Any light industry around etc.?
Why do you get so many powercuts???



For reference attenuation vs synch speed (ideal conditions):

http://adsl.yesyes.info/pics/att_vs_speed.jpg

In reply to a post by Opti:

Do I have to find the exact post just to satisfy you?

Don't bother! I was merely expressing an opinion; admittedly based on the usual NM of 6 db.

Also GeeTee's just posted "ideal conditions" referenced graph confirms my view. So, there is no need to be so antagonistic!

Edited by XRaySpeX (Sun 16-Aug-09 00:42:24)

I'd love to be able to run a 6dB NM, but it just isn't possible where I live - too much noise. I have to be up at 12dB to keep the errors to a manageable level, anything less and whilst it maintains synch, it is pretty horrible to use as the error count goes through the roof.

Such is life... and I'm certainly not going to be wasting any effort getting engineers out about it - nothing they can do

Nearest CAB is not far at all (~200meters) and the last BT Engineer confirmed these issues are completly gone from that point.

Only one cable goes from that CAB to this Building to my knowledge, only one cable comes up from underground, which is within 2cm of this buildings mains cable as well at least.

The area is residential, no commercial buildings near by that I'm aware of. And powercuts are rare here, I was lucky to be at the PC during the powercut I had last month. The previous powercut before that was years ago and after that power cut I logged into the router to discover it was synced at over 7Mbps, which is why I then bought the UPS.

Edited by Opti (Sun 16-Aug-09 00:51:39)

Well if that incoming bundle runs parallel to the mains incomer for any distance - therein lies your problem - and explains the behaviour post power-cut... the noise and cross talk will grow and grow as people power things back on - at least presuming it is a multi-occupancy building (flats etc.).

If it is a block of flats, what state is the cabling in from the incoming bundle to the flat itself... and is it correct grade telco cabling or some dicky alarm cabling used to save costs (all too common unfortunately!)?

Only option I see you have left to try is trying a different pair in the bundle.

edit - typo

Edited by deleted (Sun 16-Aug-09 00:56:33)

Both cables are shielded though? I also don't understand why in both power cuts were I've monitored the line it takes 10 minutes before the SNR starts going down?

This is a 6-property flat building, and the cabling appears to be decent quality CAT5

Like you I need 12dB before the errors even go down to a low number, although my high Interleaving Depth allows the line to cope at 7dB.

I am under the impression that everyone in this area is experiencing the same problem so I do not see why BT wouldn't be interested in fixing it.

As you have said the problem is between the property and nearest cab it seems odd that everyone in the area has the same problem. Depends how big an area you mean I suppose - maybe all served by the same cab?

As for the shielding.. sure it helps... but it's never perfect. And has it even been checked to be connected correctly and continuous on both the telco and mains?

BT (more accurately Openreach) aren't interested in fixing it because they don't have too.

You haven't said what LLU provider you are with - but whichever, they will be paying Openreach for access to the copper pair from the exchange to the premises.

The only pair quality Openreach are obliged to provide (as agreed by the industry and Ofcom) is pretty minimal. A copper pair of the minimum quality would be lucky to support DSL at all. There is no correlation ~at all~ in this minimum specification about quality vs. distance.

So your LLU provider has no stick to beat Openreach with to address your issue and Openreach has no incentive to do it at their own expense.

I expect all the engineer visits are being charged to your LLU ISP at circa ~£170 each time as technically - according to the requirements.. there is no fault. I hope your SP doesn't have a policy of passing on charges!

This is a small housing estate and I know people outside of this housing estate get 8Mbps sync (A couple roads away), one of the BT Engineers mentioned another local property getting slower speeds than me. From what I understand, any interference if it is on the mains would only get as far as the Mains Transformer? We have our own transformer just for this estate.

Are you saying that Openreach are obliged to provide Cooper and are not allowed to use Ali?

I don't want to keep incurring costs to my ISP, even though they do not pass on the charges to me. (I'm on Sky, as shown from the broken speedtest images in my first post)

Now I feel bad about trying to get my ISP to sort out the problem. (I understand that wasn't you intention though, its more the fact I know how many engineers they've sent out over the years!)

I guess I'll give up and accept that fact no matter what I'll be stuck with 4-5Mbps until FTTC.

Actually Is it worth me looking into bonding 2 lines?

Edited by Opti (Sun 16-Aug-09 02:05:12)

Your Mains Transformer understanding is incorrect. If the telco bundle from the cab runs parallel to the mains bundle for any distance there will be cross-talk between the two - even if the shielding is intact and in perfect order on both it does not block 100%.

Openreach are not obliged to provide copper, they can use Ali if they see fit. However the use of Ali has not been common for 20 years or so. Places like Milton Keynes are rife with the stuff and it cripples DSL speeds. Openreach are not obliged to replace it with copper (afaik) either. There was a copper overlay for ali areas initiative run by BT at one point, but that was before the industry as a whole decided BT needed spitting up.

I didn't mean to make you feel bad... I was just explaining the reality of the LLU market as it is now and identifying some of the stupid things the industry has agreed to in trying to break the BT monopoly.

It is certainly worth looking at bonding if you really need to boost your peak throughput. However I would suggest not doing it unless you can find an ISP that offers a solution that bonds the PPP sessions rather than just randomly bonding two DSL circuits with something like the Neteyes Cyclone router. The protocol routing is a nightmare.. particularly if you use FTP regularly.

I believe Nildram (now part of the Tiscali.. oops.. Carphone/TalkTalk group) used to (may still do) offer a bonded PPP product.

Bonded PPP is far more effective than doing it yourself. You get 2 routers or in some cases one router with two ADSL interfaces - at the ISP end the PPP session is bonded into one and automagically you get one IP assigned over two sessions. This way you avoid all kinds of issues regarding IP address based session applications and the load balancing across the two is seamless.

They are rare products these days and usually not cheap.

Can Sky offer a 2+ profile / product? Is Be LLU in your exchange?

edit - another typo

Edited by deleted (Sun 16-Aug-09 02:33:03)

Ok, so in this case the people who designed this building were idiots
Is there anything I can do at all to get the shielding improved/checked?

How much affect is this likely to have on VDSL2, which is presently my only hope for faster interent here without it costing a arm and a leg?

I only feel I need around 10Mbps to meet my needs, but it also needs to have lower latency than this connection so I'll need 3 Lines (3x3.5Mbps) to bond to this due to requring a lower interleaving depth.

I looked at Nildram but I get the impression they will never be able to meet my needs. (I pull upwards of 500Gb/month, usually data backups from my servers)

I'm thinking maybe I should buy 3 PCI ADSL2+ Cards and bond via my own servers? They are only 6ms away from my exchange.

But this is going to be costly, is there anyway to get BT line installs cheaper? Anyway I can get around the line rental? We'd be talking about 100pounds/month just for 10Mbps. (I am thinking UK Online for the other two lines)

Edited by Opti (Sun 16-Aug-09 04:00:20)

A little harsh perhaps? As far as I know architects don't take into consideration DSL performance when designing buildings. And when tasked to a building co. to construct with a budget they will do the most cost effective thing which is commonly to pull all utilities in together to a common point and distribute from there.

As for VDSL2 - sorry I don't have any information on local interference.

Why do you need the low latency?

How do you know it's 6ms to your exchange? In any case it's only relevant what your first hop to your ISP BRAS is.

BT (Retail) are offering free line installs at the moment subject to conditions. Search this forum for detail because I don't know them

I wonder what you are doing that requires half a terrabyte a month (I assume you meant 500 GB not 500Gb) with low latency and 10Mbps. Not a normal residential user profile for sure so don't expect to do it on residential packages. Maybe a niche 2+, no cap, 1:1, QoS for relevant traffic package. These are available.

The speedtest images don't really mean much. You've probably got the exchange virtually to yourself during a power cut. Likewise, there's going to be virtually no crosstalk in the bundled cables from the cab.

I'm more intrigued why you're on G.DMT rather than ADSL2 or 2+.

John.

Edited by deleted (Sun 16-Aug-09 09:53:34)

In reply to a post by Opti:

Hi all, first post here. I'll try and keep this post short despite the length of the on-going issue.

My area can only get around 5Mbps on LLU (Even less on BT Wholesale ISP's due to a very high training target SNR), but this doesn't add up because I've seen people getting ~14Mbps with the same attenuation (~38dB) as me on ADSL2+, and many many people getting full 8Mbps sync with the same attentuation on ADSL2.

On top of this, my line works how I'd expect it to every time there is a power-cut. (UPS ) It even lasts for 10 minutes after a power-cut, at which point suddenly the SNR plummets until Sync is lost. It then re-syncs and I'm back to my laggy 4meg of throughput.

BT point-blank denied any issues until recently when a Engineer confirmed the line gives several more megabips at the nearest CAB. However they have still yet to do fix the source of this problem.

My full router stats are posted below, and i'm hoping some of you can help finally solve this. I have a portable AM radio here if that can help at all?

Power-Cut Performance
[IMG]http://speed.io/pics/2179/0434/speed.io.png[/img]
Normal Performance
[IMG]http://speed.io/pics/2327/3185/speed.io.png[/img]

Text

1 23 45 67 89 1011 12

ADSL driver and PHY status Status: ShowtimeRetrain Reason: 1Channel: INTR, Upstream rate = 768 Kbps, Downstream rate = 5024 Kbps Link Power State: L0Mode:                   G.DMT Channel:                InterleaveTrellis:                ON Line Status:            No DefectTraining Status:        Showtime                 Down            UpSNR (dB):       6.9             14.0 Attn(dB):       38.0            25.0

Obviously there's a lot of noise on your line, probably caused by local interference. By local, I mean in your house.

We're not talking mains interference here more likely RF (radio frequency) interference.

Who is your ISP?
Why are you on g.dmt not ADSL2+?
Have you removed your ringwire?

(I'm on Sky, as shown from the broken speedtest images in my first post)

John.

Ah, that implies the sky-box, a well-known source of RFI. It also explains why g.dmt not ADSL2+.

A things:

1. Switch off mains in your property at the main fuseboard and see if performance is better
2. If yes, then switch each fuse back on to help identify which circuit, and then you can go through all the kit on that circuit
3. Are you using master socket for the ADSL, with an ADSL faceplate, or IPlate or have removed the ring wire? All things that can make the ADSL less prone to interference
4. Buy a proper twisted pair RJ11 lead for modem - may help a little
5. Use an battery powered AM Radio to try and find the source of noise, i.e. tune it off a station a bit and see if the noise is worse in one particular area
6. The improved speed outside of a powercut may be down partially to less cross talk from other ADSL lines in the area, i.e. power goes off 98% of modems will then be off crosstalk vanishes, and if your estate has a very high >75% takeup of ADSL it can have an effect.

I fear, Opti, that you'll not get too much help here if you adopt the shirty attitude "Do I have to find the exact post just to satisfy you?".
Most people on the TBB sites are friendy, and such a brusque attitude will get you nowhere.
As an aside, unless you're resident elsewhere than the UK, then METRES is spelt just that, not METERS.

"METRES is spelt just that, not METERS"

It is. I've got two under the stairs

John.

Yes John, but how many meters - gas & electricity - standing side by side, is it before you reach the nearest street cab.
Cheers, Les.

Edited by lelboy (Sun 16-Aug-09 16:35:28)

"nearest street cab"

There's one parks up overnight about 4 doors away

John.

Do they let you have the manure for your roses?

Yeah. In exchange for some oil for their lamps.

John.

They must be hansome

You don't see many green ones with a wheel at each corner - although the owners of both sorts spend their time ripping us off...
Les