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Standard User woodyblade
(newbie) Fri 27-Jan-12 21:56:04
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Attainable Rates dropped


[link to this post]
 
Not sure if I'm posting in the correct forum (might fit in Technical Issues as well).

Anyway I've been trying to work out why attainable rates have suddenly dropped on my line, had it installed 3 months ago and a couple of weeks later (after unlocking the modem) found that attainable rates on the line fluctuated between 70-85mbps(15-19~ SNR)/25-26mbps (22-23~ SNR).
Went to check it at the beginning of this week and found rates had dropped considerably to 52mbps(10~ SNR)/20mbps(13~ SNR), so went to reboot the modem and no change still stuck at those attainable rates and it doesn't budge from those either, unlike before where the SNR moved between the ranges I mentioned above.

I've had a look at the wire between the old master socket and new one, it is fastened to the skirting board with those small metal pins (it's crushing the wire down at points which doesn't look right to me) and upon looking closer one of them looks to have pierced the wire (or at least the edge) though am not overly sure if that would cause such a massive drop in rates.
Errors on the line haven't increased, or at least those shown on the modem interface, at those attainable rates it won't be worth upgrading but at 70mbps it would have been.

I'm wondering if there is anything else I should try or look into to find what the problem is?

As networking isn't my strong point, more my weak point of technology, also I've pasted below previous (these were middle of the SNR range I mentioned) and current stats.

Before:
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 26974 Kbps, Downstream rate = 78428 Kbps
Path: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 26974 kbps 78428 kbps
Actual Aggregate Tx Power: 6.9 dBm 13.4 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 4.6 21.9 31.4 N/A 11.7 27.0 41.1
Signal Attenuation(dB): 8.1 21.4 30.2 N/A 11.7 27.0 41.1
SNR Margin(dB): 22.4 21.9 22.8 N/A 17.5 17.8 17.6
TX Power(dBm): -4.1 -24.8 6.4 N/A 10.8 7.6 6.0

Now:
# xdslcmd info --pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 20685 Kbps, Downstream rate = 52316 Kbps
Path: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 20685 kbps 52316 kbps
Actual Aggregate Tx Power: 6.9 dBm 13.7 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 4.6 21.9 31.5 N/A 11.7 27.1 41.1
Signal Attenuation(dB): 8.2 21.0 30.2 N/A 11.7 27.1 41.1
SNR Margin(dB): 13.5 13.6 13.5 N/A 9.5 9.8 10.2
TX Power(dBm): -4.1 -24.6 6.5 N/A 11.0 8.0 6.6

Edited by woodyblade (Fri 27-Jan-12 21:58:04)

Standard User Bald_Eagle1
(member) Fri 27-Jan-12 23:34:31
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
Hi woodyblade,

Comparing your attenuation & power stats I can see some very minor fluctuations, probably not enough for any concern.

I would have thought that any cable defects would have increased attenuation levels quite substantially.

However, I can see that your SNRM levels have lowered substantially:-

Text
1
23
45
6
Before:
                         U0      U1      U2      U3      D1      D2      D3SNR Margin(dB):          22.4    21.9    22.8    N/A     17.5    17.8    17.6
 Now:
SNR Margin(dB):          13.5    13.6    13.5    N/A     9.5     9.8     10.2


That would suggest to me that either your connection has become generally "noisy", or that the connection has re-synced at "noisier" times e.g. evenings.
Thus the lower attainable rates.

SNRM tends to rise during daylight hours, peaking between noon & 2:00 p.m. & is at its lowest between 11:00 p.m. & 1:00 a.m.

You could try a re-sync / reboot between noon & 2:00 p.m. tomorrow to see if that improves matters.

If not, you could try to find the cause of the "noise" - maybe some new electrical equipment, electrical equipmnet beginning to "fail", or possibly simply increased cross-talk from one or more new broadband subscribers in your area.

It could even be radio interference. Has a radio ham recently started transmitting at high or higher power levels?

If it's none of the above, I can't think what to suggest.

Do you have any PuTTy or other logs from when attainable rates were higher & any recent ones to compare against each other (graphically)?

The most useful commands, run one after the other are:-

xdslcmd info --pbParams
xdslcmd info --Bits
xdslcmd info --linediag
xdslcmd info --show
xdslcmd info --stats


Paul.

Edited by Bald_Eagle1 (Sat 28-Jan-12 00:01:19)

Standard User woodyblade
(newbie) Sat 28-Jan-12 00:27:01
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
Thanks for replying, yeah I would have expected more noise as more people may have moved over to fibre in my area, but haven't seen too many HH3 routers signals popping up, not that I go around checking every street mind you, just what I notice if I walk down the street.
But wouldn't expect such a big drop in a short time, unless the whole street has joined and the BT installers have been going around like blue proverbial flies.

I've checked the noise margins at a few times during the day, 8am/5pm/12am it seems to be fixed at the figures I quoted give or take a couple of .1/.2's here or there.
I would have thought a couple of digits variation like I saw previously and on ADSL as well where I saw similar 3-4 digit variations in SNR would be the norm, just seems odd for it to be fixed like that.

We personally haven't installed any new electrical equipment recently, not sure if the neighbours have, but only those next door (live in a semi-detached) should affect us if at all because other neighbours I would think are a big enough distance away for any interference to not affect us.
I don't think there are any new radios in the area, though wouldn't be sure, I know all cell masts are at least a mile away looking on Sitefinder, though doubt they would cause anything to go wrong.

Looks like I'm running out of reasons, I know your own problems with your actual speeds dropping below 30mbps, so glad I'm lucky enough to get the full speeds which will be good for the foreseeable future (and a damn sight better than 3mbps on ADSL), but obviously quite disappointing to see such a potential speed drop as I see it as more future proofing against BT's slow and dithering approach to investing in fibre, obviously the Government could help but won't, it's spending £30bn on HS2 but won't place more money into 4th utility.
At the rate BT is investing (from previous decades as well) we'll be behind again in a decade and playing catch up all over again.

Unfortunately I've never graphed or recorded the connection details, I'll give you the --show, --stats and --pbParams printouts taken now but not sure what I'm meant to do to get the data for the --Bits and --linediag outputs.
--pbParams
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 20715 Kbps, Downstream rate = 52316 Kbps
Path: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 20715 kbps 52316 kbps
Actual Aggregate Tx Power: 6.9 dBm 13.7 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 4.6 21.9 31.5 N/A 11.7 27.1 41.1
Signal Attenuation(dB): 8.0 21.0 30.2 N/A 11.7 27.1 41.1
SNR Margin(dB): 13.6 13.6 13.6 N/A 9.5 9.8 10.2
TX Power(dBm): -4.1 -24.6 6.5 N/A 11.0 8.0 6.6


--show
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 20696 Kbps, Downstream rate = 52532 Kbps
Path: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps

Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 9.9 13.5
Attn(dB): 0.0 0.0
Pwr(dBm): 13.7 6.9
VDSL2 framing
Path 0
B: 239 111
M: 1 2
T: 64 50
R: 0 16
S: 0.1909 0.7101
L: 10055 2704
D: 1 1
I: 240 120
N: 240 240
Counters
Path 0
OHF: 58413296 1283270
OHFErr: 722 191
RS: 0 4192607
RSCorr: 0 78
RSUnCorr: 0 0

Path 0
HEC: 4202 0
OCD: 0 0
LCD: 0 0
Total Cells: 858445265 0
Data Cells: 176966326 0
Drop Cells: 0
Bit Errors: 0 0

ES: 625 188
SES: 0 0
UAS: 22 22
AS: 179161

Path 0
INP: 0.00 0.00
PER: 3.05 8.87
delay: 0.00 0.00
OR: 65.46 55.88

Bitswap: 1076 1476


--stats
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 20719 Kbps, Downstream rate = 52316 Kbps
Path: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps

Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 9.8 13.6
Attn(dB): 0.0 0.0
Pwr(dBm): 13.7 6.9
VDSL2 framing
Path 0
B: 239 111
M: 1 2
T: 64 50
R: 0 16
S: 0.1909 0.7101
L: 10055 2704
D: 1 1
I: 240 120
N: 240 240
Counters
Path 0
OHF: 58424055 1286859
OHFErr: 722 191
RS: 0 77079
RSCorr: 0 78
RSUnCorr: 0 0

Path 0
HEC: 4202 0
OCD: 0 0
LCD: 0 0
Total Cells: 860976654 0
Data Cells: 177004199 0
Drop Cells: 0
Bit Errors: 0 0

ES: 625 188
SES: 0 0
UAS: 22 22
AS: 179194

Path 0
INP: 0.00 0.00
PER: 3.05 8.87
delay: 0.00 0.00
OR: 65.46 55.88

Bitswap: 1076 1476

Total time = 1 days 1 hours 46 min 57 sec
FEC: 0 0
CRC: 722 0
ES: 625 188
SES: 0 0
UAS: 22 22
LOS: 0 0
LOF: 0 0
Latest 15 minutes time = 1 min 57 sec
FEC: 0 0
CRC: 0 0
ES: 0 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
Previous 15 minutes time = 15 min 0 sec
FEC: 0 0
CRC: 2 0
ES: 2 0
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
Latest 1 day time = 1 hours 46 min 57 sec
FEC: 0 0
CRC: 18 0
ES: 18 7
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
Previous 1 day time = 24 hours 0 sec
FEC: 0 0
CRC: 350 0
ES: 309 97
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0
Since Link time = 2 days 1 hours 46 min 33 sec
FEC: 0 78
CRC: 722 191
ES: 625 188
SES: 0 0
UAS: 0 0
LOS: 0 0
LOF: 0 0


Thanks

Edited by woodyblade (Sat 28-Jan-12 00:33:15)


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Standard User Zarjaz
(knowledge is power) Sat 28-Jan-12 08:35:57
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Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
All the sources of potential interference mentioned by Bald Eagle are going to be tricky to find, unless it's REIN based.

In your first post you mentioned the wire between the sockets, is this a 'data extension' cable, does the the socket where the modem plugs in have a small computer symbol on it ? If so, are these cleats or staples that have been used to fix between the two ? Staples are a big no-no, they too easily pinch the twisted pairs.

The cross talk, if it is that causing this issue, is more likely to be nearer the cabinet end, as you pair goes through larger cables and increases it's chance of laying near another VDSL circuit. It *might* be this, who knows.

You also mentioned just the 'b' light going off on the HH3, it's not unknown for these to pack up.

Have you been brave and spoken with BTBB tech support ? Jump through all the hoops and see if they can raise an 'FTTC Boost' task and get an engineer out. If you have any joy with this, let us know and I'll tell you what you need to be looking for when they attend.

p.s. I suspect it's best to keep it simple when you speak to BTBB, no mention of varying attainable rates, just, 'it keeps disconnecting'.

Standard User Bald_Eagle1
(member) Sat 28-Jan-12 08:41:16
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
Hi woodyblade,


Right, what I see from your stats so far is:-

Your connection is actually making use of all 3 of the 17a band plans:-
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)

My own conection is only able to make use of some of the first 2 band plans.

DS & US Power levels look O.K:-
Pwr(dBm): 13.7 6.9

Interleaving is OFF for both DS & US (value for each = 1):-
D: 1 1

(O)ver(H)ead (F)rame (E)rrors look quite low:-
OHFErr: 722 191

Corrected errors are low & only on your US:-
RSCorr: 0 78

Uncorrected errors are non-existant:-
RSUnCorr: 0 0

Error seconds are low:-
ES: 625 188

Serious error seconds are non-existant:-
SES: 0 0

Unavailable seconds are low:-
UAS: 22 22

Your connection has been up for almost 50 hours (179161 seconds since re-sync)
AS: 179161

Impulse Noise Protection isn't needed:-
INP: 0.00 0.00

There is no delay:-
delay: 0.00 0.00


In other words, so far, so good.

However, what is also needed from info --linediag & info --Bits is details of:-

attenuation over frequency (Hlog)
Signal to Noise Ratio (SNR, not SNRM)
Quiet Line Noise (QLN)
Bit-loading per tone (Bits)


With all the various xdslcmd info data (ideally in a single log file, bit at a pinch in separate log files), we could graph your stats each time your attainable rates changed (or at least obtain a snapshot of how they look at any given time)
It's a million times easier to study a graph than thousands of rows of raw data.

e.g. My poor connection:-
Poor Connection

Another user's much better connection:-
Better Connection

Your own connection would probably have looked a lot like the better connection example when your attainable rates were higher.

I can graph my stats whenever I wish, which is O.K. & I can see minor fluctuations.
The problem in trying to diagnose my connection's much lower speeds & current instability is that I do not have any stats from when my connection was much better.
That was at the time before we had access to our stats.

It's a shame you don't have the data from when your attainable rates were higher as that MIGHT have given a really good comparison against your current stats & a possible bargaining tool to prove that an engineer's visit is required to "fix" a line fault.

You MIGHT be able to get all the data into a single log file via telnet:-
telnet -f telnet.log 192.168.1.1

However, telnet times out & loses connection part way through for me.

Or, you could use PuTTy, freely available from:-
Putty Download

Or, if you are a Windows user and you are prepared to spend a little time setting things up, you could use the batch files & other downloads as per the link in the first pos in this thread:-

Huawei HG612 Modem - Stats & Graphs for Windows Users

Once set up, it just takes a simple double-click to graph a snapshot like the examples above, or to graph your ongoing stats showing any changes over the last few minutes, hours or days.
A lot more ongoing data is collected than is currently plotted, that can be viewed as raw data, or with a little tweak here & there could be plotted.


Paul.

EDIT:
I have to mention that any data/stats as mentioned above would be obtained "unofficially" & possibly in breach of your terms & conditions for the use of the Openreach owned modem.

So as Zarjaz mentions, initially keep it very simple.

Just a last one, is there any noise from a quiet line test by dialing 17070 & picking option 2 and/or does your modem's GUI show any big reductions in SNRM levels while using the phone?
I had that issue for a while, SNRM dropping to as low as 1.5dB while using the phone, & causing occasional connection re-syncs (although the phone was quiet at the time).
An engineer replaced a good few metres of drop wire & that particular issue was resolved.

Edited by Bald_Eagle1 (Sat 28-Jan-12 09:00:02)

Standard User Bald_Eagle1
(member) Sat 28-Jan-12 08:45:54
Print Post

Re: Attainable Rates dropped


[re: Zarjaz] [link to this post]
 
I have also read about, but not personally experienced, a modem power supply starting to fail, causing a similar effect.

A straight swap of the power supply cured the problem.

A direct PC to modem connection might be worth a try, as you could then eliminate the router from the equation as a potential source of the problem.

Edited by Bald_Eagle1 (Sat 28-Jan-12 08:47:52)

Standard User Bald_Eagle1
(member) Sat 28-Jan-12 09:07:29
Print Post

Re: Attainable Rates dropped


[re: Zarjaz] [link to this post]
 
Hi Zarjaz,

In reply to a post by Zarjaz:
All the sources of potential interference mentioned by Bald Eagle are going to be tricky to find, unless it's REIN based.


For curiosity, as it may just be having some effect on my own connection's reduced speeds, have you had any personal experience with successful REIN investigations?

I have read that it is a very specialised field & that ISPs/BT are usually VERY reluctant to take on REIN issues.
No doubt it can take many hours & therefore be very costly.


Paul.
Standard User RobertoS
(sensei) Sat 28-Jan-12 09:25:28
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
haven't seen too many HH3 routers signals popping up
A bit of useless info re solving the problem, but FTTC isn't just BT Infinity with Home Hubs. There are many ISPs supplying FTTC and a wide variety of routers around, as with ADSLx and modem/routers.

Other ISP takeup is very low compared to Infinity, I grant you that, but BT love us to think there is no alternative, and I don't like to see the misconception reinforced for any newbies reading smile.

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - IDNet Home Starter Fibre. Live BQM.

"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
Standard User Zarjaz
(knowledge is power) Sat 28-Jan-12 10:50:55
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
have you had any personal experience with successful REIN investigations?

Yes. To be fair, have only seen one guaranteed REIN fault on an FTTC line. Due to v.dodgy lighting in a factory, killing it stone dead.
I have read that it is a very specialised field & that ISPs/BT are usually VERY reluctant to take on REIN issues.

Yes, only a handful of engineers have the skill set/equipment to deal with these. I have been on to my boss to get me the 444 meter used to help locate these faults, as I have borrowed them in the past and successfully located sources, but they are hideously expensive [sad].

No doubt it can take many hours & therefore be very costly.

Yes !

Standard User Bald_Eagle1
(member) Sat 28-Jan-12 11:03:04
Print Post

Re: Attainable Rates dropped


[re: Zarjaz] [link to this post]
 
Cheers Zarjaz,


In reply to a post by Zarjaz:
Yes. To be fair, have only seen one guaranteed REIN fault on an FTTC line. Due to v.dodgy lighting in a factory, killing it stone dead.


Just to give us a bit of insight into this, how close would you say the factory was to the cabinet/connection/end user & what sort of lighting was involved?

Paul.
Standard User Zarjaz
(knowledge is power) Sat 28-Jan-12 12:35:09
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
The affected service was in the office of the factory in question. I can't remember what kind of light it was, big [censored] up in the factory/warehouse ceiling, very expensive/bright.

The big p**s take was that the punter already knew that they were causing a problem, as had been identified before by a REIN engineer previously when they had ADSL. They were declining to do anything about, and yet happy to keep moaning to their ISP.

There's no pleasing some folk. [sad]

Administrator MrSaffron
(staff) Sat 28-Jan-12 12:43:45
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
Ranges of 100m are not unknown for RF problems.

Also as VDSL uses a much wider range of frequencies it may start to show up new sources of REIN. Odd that with the UK being so far behind that there is so little information from other countries on this - one could conclude that just maybe either

1. The UK is really not far behind the curve
2. We want other people to fix things
3. We enjoy moaning

Andrew Ferguson, [email protected]
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User Zarjaz
(knowledge is power) Sat 28-Jan-12 12:59:33
Print Post

Re: Attainable Rates dropped


[re: MrSaffron] [link to this post]
 
Ranges of 100m are not unknown for RF problems.

Easily, when airborne, even further if the source has an easy path on to the bearer network, Sky boxes for example.

Standard User woodyblade
(newbie) Sat 28-Jan-12 13:13:38
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
@Bald_Eagle1

Yeah I thought the stats looked ok from when I was looking at them.

How would I log results in Putty that's how I've been reading the more detailed stats currently?
I did attempt those scripts but don't think I've set them up correctly.

Yep knew about not mentioning the modem stats to BT, as for the quiet line test we only have cordless phones in the house so not an accurate measure, but listened to it for a minute and there was no crackling or clicks that I could hear, just a faint buzzing but I'm pretty sure that's because it's a cordless phone.
As for using the phone the SNR does drop ever so slightly 0.2 on DS, but I doubt that is anything to be concerned about, as a side note it was worse than that, the line previously dropped out on ADSL, dropping approximately 3-4db when using the phone and I'm pretty sure we never found that problem, we switched providers at the time from TalkTalk to Sky and it didn't crop up again, though the SNR still did drop when we used the phone.

----------------------------------------------------------------------

@Zarjaz

Yeah this wire connects between our old master socket (which the BT Engineer said is now inactive) to the new one, I would assume it's ordinary phone extension cable.
Yes this is fastened down with metal staples, I'll reiterate (though I know I should see line attentuation increase as well) that they really are fastened down tight to the point of crushing the wire at every point the staples are at and as mentioned one does look to have pierced the wire.

I'm not sure what you mean by this part exactly, I've never seen a small computer symbol "does the the socket where the modem plugs in have a small computer symbol on it ? If so, are these cleats or staples that have been used to fix between the two ?"

Cross talk does seem more plausible at the minute and I wouldn't be surprised if someone had it installed recently with the rubbish ADSL speeds round here, the cabinet does serve about 20 different postcodes, plus there is a Digital Region cabinet as well, installed about 3-4 months ago, so the possibility for a lot of connections.

I've not used the HH3 router since the first day it was installed, once the BT Engineer went I took it out and put my own back in.

I may have a look at phoning BT's support line but will wait and see what BT estimate in the updated data soon, ironic that the attainable rate drop happens a week before BT update the speeds on the checker.

--------------------------------------------

@RobertoS

Yeah didn't mean to explain it like that, in regards to HH3 being the only sign of fibre installs, just that I doubt there has been such a big increase in installs to cause such a drop in attainable rates.

Thanks for the replies so far as well
Standard User Bald_Eagle1
(member) Sat 28-Jan-12 14:42:17
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
In reply to a post by woodyblade:
@Bald_Eagle1

Yeah I thought the stats looked ok from when I was looking at them.

How would I log results in Putty that's how I've been reading the more detailed stats currently?


These are the PuTTy settings that I used to use (manually):-

1) Open PuTTy
PuTTy_1

2) Click on Logging:-
PuTTy_2

Browse to a folder of your choice & enter a name for the log file (if one isn't already offered)

3) If you get asked about overwriting, click Yes:-
PuTTy_3

4) Type in the first xdslcmd:-
PuTTy_4

5) As soon as it has finished, type in the next command:-
PuTTy_5

6) When you have run all the commands, close PuTTy by clicking the red 'X' then click "OK":-
PuTTy_6

7) You should end up with a text file that contains ALL the relevant data:-
PuTTy_7


The resulting log file is too big to post in a forum (thousands of lines).
Either upload it somewhere & post a link to it, or PM me with your email address & I'll let you know how to get it to me so that I could plot the data for you (as a one-off).



I did attempt those scripts but don't think I've set them up correctly.

You could have a look here. It MIGHT help to simplify things:-

Step-by_step


As for using the phone the SNR does drop ever so slightly 0.2 on DS, but I doubt that is anything to be concerned about

Yep, that's all I get since the engineer replaced a section of drop wire.
I would guess that is normal?

HTH,


Paul.

Edited by Bald_Eagle1 (Sat 28-Jan-12 14:44:09)

Standard User Zarjaz
(knowledge is power) Sat 28-Jan-12 15:37:30
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
Yeah this wire connects between our old master socket (which the BT Engineer said is now inactive) to the new one, I would assume it's ordinary phone extension cable.
Yes this is fastened down with metal staples, I'll reiterate (though I know I should see line attentuation increase as well) that they really are fastened down tight to the point of crushing the wire at every point the staples are at and as mentioned one does look to have pierced the wire.

I'm not sure what you mean by this part exactly, I've never seen a small computer symbol "does the the socket where the modem plugs in have a small computer symbol on it ? If so, are these cleats or staples that have been used to fix between the two ?"

Sounds as though the engineer has extended the internal wire and shifted the NTE, rather than fit a data extension kit. In this instance, staples are acceptable.

Standard User woodyblade
(newbie) Sat 28-Jan-12 16:01:27
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
@Bald_Eagle1

Ran those commands in Putty and got a 330KB file, what software would I use to plot the data, GNUPlot?
I'll send you an PM about sending the file over.

EDIT: Managed to get those scripts working now, it was me skim reading over things (it'll get me in trouble one day), didn't set the system path correctly, now I just need to work out how to set them to record data for set times, can't work that bit out (or I may have missed it in the instructions again).

Ok got it set to run every minute via Windows Scheduler, how can I hide the command prompt from appearing everytime?

@Zarjaz

Ok no problems, guess the wire is fine so I'll have to assume the problem if any is external, as the modem is the first point after the wire into the house.
Yet another unknown to how this line works.

Edited by woodyblade (Sat 28-Jan-12 17:02:52)

Standard User Bald_Eagle1
(member) Sat 28-Jan-12 20:23:50
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
In reply to a post by woodyblade:
@Bald_Eagle1

Ok got it set to run every minute via Windows Scheduler, how can I hide the command prompt from appearing everytime?


Which version of windows are you using?
Standard User woodyblade
(newbie) Sat 28-Jan-12 22:08:58
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
I'm running Windows 7.
Standard User WWWombat
(committed) Sat 28-Jan-12 23:12:49
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
Sorry I'm a bit late on this... I haven't had a chance to look through this thread so far.

My glance at the before/after "pbParams" data suggests that:
- The attenuation hasn't changed, so it doesn't look like anything catastrophic has happened to the line
- The power levels have gone up slightly, suggesting that the signal level ought to have gone up slightly
- The SNRM levels have gone down significantly.
- The sync speeds haven't changed

Because the sync speed hasn't changed, the SNRM levels can only have gone down because noise has increased. I don't think it has anything to do with the time of day of the last sync, as you still managed to get to the full sync speed anyway. The increased power means that *something* has noticed this, and tried to compensate; the higher signal level means that noise has probably increased more than the simple difference in SNRM levels.

The questions then are:
- What is the cause of this noise?
- Does it affect the line all the time?
- Does it affect all frequencies?

The more that this noise happens 24x7, the more likely it is to be crosstalk than REIN. The more it is spread over all frequencies, the more likely it is to be crosstalk too (but a little less certainly).

Before attributing things to REIN, and starting a lengthy investigation, perhaps we should consider whether the drop can feasibly be attributed to crosstalk.

My (currently) favourite documents on Vectoring give some good graphs on the impact of crosstalk (so you can then see how good Vectoring is at fixing it). One is found here (look at graphs on page 14 and 15 for 0.4mm cable), and the other is found here (page 9 for 0.5mm cable).

A favourite quote in there is "In an environment where several VDSL2 systems are in the same cable binder, it is FEXT (far-end crosstalk) that severely limits the performance." Just as a reminder that crosstalk is significant... and that the interference comes more from the cabinet-end, so it doesn't have to be a close neighbour to have an effect.

How significant? The graphs suggest, for 0.5mm cable, a speed drop from 80Mbps to 55Mbps (at 3000 feet, or 1000 metres). Or for 0.4mm cable, a speed drop from 70Mbps to 52Mbps (at 1800 feet, or 600 metres.

So that kind of drop *is* possible, but it probably requires more than one crosstalk-ing line.

Probably the first questions I'd ask are:
- How far are you from the cabinet?
- How much does the speed vary over a few days? Are there sharp changes in variation, or just sudden drops & increases?
- Was the drop from 70-80 down to 52 a sudden one, or could it have been spread over weeks?
Standard User woodyblade
(newbie) Sun 29-Jan-12 00:07:06
Print Post

Re: Attainable Rates dropped


[re: WWWombat] [link to this post]
 
Approximately 600m to the cabinet by my estimates, actual measurements by road/footpaths is about 500m so I added 100m on top to be conservative.
Though because I never saw the engineers JDSU I wouldn't be able to get an exact measurement or thickness of the cable.

Though it does really seem to match that 0.4mm measurement you quoted, on the low end at least.

EDIT: On closer looking at the links mine looks to be more like 0.5mm, because the 70mbps and more I previously saw would only be possible at 350m (more like as the crow flies distance for me) or less on 0.4mm.
Though based off the speeds my line length must have suddenly doubled for that drop to have occurred, obviously nigh on impossible.

Like I said in the first post before this drop the speeds varied between 70-85mbps, so there was reasonable variation of about 4db on SNR.

This drop was pretty sudden like a matter of a day or two at most from when I'd previously checked it, I'd been keeping an eye on it for a week or so to see the range of change and see what BT estimated.

Yeah after the suggestions previously, I was thinking more and more that crosstalk was looking like the cause, obviously being a relatively new technology to us in the UK there are unknowns, but I'm still very surprised that such a large drop would occur this quickly it doesn't bode well for everyone else if this sort of drop occurs with crosstalk.
It's looking like those within 200m-300m will be the lucky ones and everyone else will get good speeds which won't be good in 5-10 years time.

Edited by woodyblade (Sun 29-Jan-12 00:16:28)

Standard User Bald_Eagle1
(member) Sun 29-Jan-12 00:48:23
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
In reply to a post by woodyblade:
I'm running Windows 7.


Update 29/01/2012:

I have now added some setting up instructions that include some screenshots to the main download zip file (hg612_wingraphs.zip):-

These instructions are named Setting_Up_Instructions.pdf

The PDF file can also be viewed/downloaded on its own at the main download site:-

Huawei HG612 Graphing Scripts


Paul.
Standard User Croftie
(member) Sun 29-Jan-12 01:15:04
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
In reply to a post by Bald_Eagle1:
Just a last one, is there any noise from a quiet line test by dialing 17070 & picking option 2 and/or does your modem's GUI show any big reductions in SNRM levels while using the phone?
I had that issue for a while, SNRM dropping to as low as 1.5dB while using the phone, & causing occasional connection re-syncs (although the phone was quiet at the time).
An engineer replaced a good few metres of drop wire & that particular issue was resolved.

If I may drop in here and ask, on my line there is a 0.7 dB drop on DS and 0.1 dB drop on US, I pressume that's nothing to worry about?
Standard User Bald_Eagle1
(member) Sun 29-Jan-12 01:25:01
Print Post

Re: Attainable Rates dropped


[re: Croftie] [link to this post]
 
I now see a slightly smaller drop than that (perhaps only 0.4dB or 0.5dB) on DS & no drop at all on US.

It doesn't appear to affect my connection anymore.
So, a good job, well done by the latest visiting engineer.

Maybe the next one will get my higher speeds back again?smile
Standard User woodyblade
(newbie) Sun 29-Jan-12 01:27:30
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
Thanks Paul very handy scripts and that last bit of information to stop the CMD window appearing every minute was the last bit I needed to set the scripts up correctly.

Here's the data from 8 hours of readings.

http://imageshack.us/photo/my-images/267/linestatsp2...
Standard User Bald_Eagle1
(member) Sun 29-Jan-12 01:45:30
Print Post

Re: Attainable Rates dropped


[re: woodyblade] [link to this post]
 
Lovely Jubbly.

Your error count graphs look rather boring - sod all to report for RS Uncorrected errors smile

I wonder what might have caused the slight increase in SNRM levels at around 22:10 tonight?
Did you notice whether or not it had any effect on your attainable rates?
Those aren't currently graphed, but they are included in modem_stats.log

From my own log, the bold & underlined values are the DS & US attainable rates:-
29/01/2012 01:42 26329 5907 5.9 6.5 12.1 6.3 30344 6085


I don't know why I bothered to set the batch files up at all.
It just makes me want to cry whenever I se anyone else's good stats/graphs frown

Edited by Bald_Eagle1 (Sun 29-Jan-12 01:47:15)

Standard User woodyblade
(newbie) Sun 29-Jan-12 01:53:16
Print Post

Re: Attainable Rates dropped


[re: Bald_Eagle1] [link to this post]
 
From looking in the log it changed in the minute between 22:13-14 from "52332/20719" to "54900/21557"

xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 21591 Kbps, Downstream rate = 54900 Kbps
Path: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps

Discovery Phase (Initial) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
Medley Phase (Final) Band Plan
US: (0,95) (868,1207) (1972,2783)
DS: (32,859) (1216,1963) (2792,3939)
VDSL Port Details Upstream Downstream
Attainable Net Data Rate: 21591 kbps 54900 kbps
Actual Aggregate Tx Power: 6.9 dBm 13.7 dBm
============================================================================
VDSL Band Status U0 U1 U2 U3 D1 D2 D3
Line Attenuation(dB): 4.6 21.9 31.5 N/A 11.7 27.1 41.1
Signal Attenuation(dB): 8.5 20.8 30.1 N/A 11.7 27.1 41.1
SNR Margin(dB): 13.9 14.1 14.2 N/A 10.4 10.7 10.5
TX Power(dBm): -4.1 -24.6 6.5 N/A 11.0 8.0 6.6


Looks like a small 0.8 increase on SNR readings, so very little.
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