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[Oranged]

I have experienced a poor sync rate since mid-April. Connection speed at 1900 - 1950 is constant without any disconnections.

Prior to that my router (Belkin 7633) showed 6656 down 288 up on a normal ADSL LLU connection without interleave and SNR 10 - 13dB, Attenuation 39 and connection would be consistently 5700 - 5800. Again with no disconnections.

Since then I normally have stats showing nothing against ADSL Type, sync at 2268 down 285 up and interleave depth on at 32 down 8 up and SNR 31 down 28 up, Attenuation 41+.

At around this time I believe my ISP, Orange, implemented ADSL2+ at my exchange.

Yesterday, the SNR started steadily dropping and reached 22.6 down 7.5 up by early evening. But during the evening SNR suddenly increased to 31 down 29 up. Coincidentally, it had started raining at around 7pm.

I run XP SP3, I have tested in the test socket with no improvement, I have changed filters with no improvement, I have connected via ethernet (rather than wireless) with no improvement.

I have made a 17070 quiet line test which returned perfect. I have requested Orange to check any changes made to the LLU service at the exchange.

Latest router stats are :

Firewall Enabled   ESSID Broadcast Disabled 
NAT Enabled   Channel 11 
UPnP  Disabled   Security WPA-PSK 
     
ADSL   

Type   !! N.B. it shows nothing against this !!
Status No Defect
Downstream     Upstream

Data rate 2268  285 
 
Noise margin 30.8  16.2 
 
Output power 20.1  11.7 
 
Attenuation 43.5  20.6



DMT shows "ADSL2+ interleaved path"and interleave depth 32 down 8 up. Down RCO 33% (6836kbps) Up RCO 47% (609kbps)

I would appreciate any comments/advice/help

[roseway]

Hi and welcome

Does the F5D7633 support ADSL2+? I downloaded the manual and didn't see any reference to it in an admittedly quick scan through. If not, that might explain the blank connection type which is shown.

Even so, I don't think that would explain the problem. It looks as though your line is subject to very heavy interference at times. This would cause the low speed reconnection, then when the interference goes away again you are left with a very high noise margin. If the same thing happens when you connect to the test socket, the source of the interference is likely to be some sort of line fault or maybe some heavy electrical machinery nearby. This page and the associated pages may give you some ideas as to the source.

[Oranged]

Hi and welcome

Does the F5D7633 support ADSL2+? I downloaded the manual and didn't see any reference to it in an admittedly quick scan through. If not, that might explain the blank connection type which is shown.

Yes it does support ADSL2+.

As there is no electrical machinery in the vicinity I guess it could be a line fault.

I did notice a gradual connection speed deterioration starting on 15 April then a sudden drop on Sunday 20 April from 5200 to 1992 with the associated increase in SNR etc.

[kitz]

>> I have experienced a poor sync rate since mid-April. Connection speed at 1900 - 1950 is constant without any disconnections.
>> sync at 2268 down
>> SNR 31 down

What happens if your try a resync when the SNRM is so high.   
Theres plenty of spare SNRM so you should be able to sync much higher than around 2Mb.  I want to  eliminate the possibility of an incorrect profile.

I know you said the SNRM can drop to 22dB..  but thats still plenty to give much more speed than what you are getting... and some lines do have large SNR variations.

Some line stats immediately after a resync would help us check the profile

[Ezzer]

For a fixed speed dsl service then the higher the snr the better, as a rough guide

target would be snr above 9, 6 or under then you'll probably get lots of drop of sync.

In the teens is average.

In the 20's is very good.

In the 30's wow.

low 40's, do you have permission to be inside that exchange ?

With rate adaptive although it's mesuring the same thing (noise over desired signal) Its giving the numbers from a completely different perspective.

so from the snr your currently getting the snrm on rate adaptive should be good which should result in a good download.

The only other thing to check is errors, as theses can come up affecting the speed without having any detriment to the snr/snrm.

on a fixed spped service you not have interleaved packets so the acceptable error rate will be much lower
over a 5 min period: errored seconds <15 , crc & hec errors <60-100 is ok 

Interleaved service crc & hec errors up to 1000 are ok, fec & rs errors up to 11000- 14500 are ok over the same period. 

It's worth bearing in mind the huge difference in acceptable errors between non interleaved & interleaved dsl, worth bearing in mind if any one's looking to turn interleaving off in order to get a bit more speed which would be proportionatly much smaller gain in comparison to the added venerability you'll get. If you lines always stable with very little in the way of errors, fine. If not worth thinking again 

[Oranged]

What happens if your try a resync when the SNRM is so high.   
Theres plenty of spare SNRM so you should be able to sync much higher than around 2Mb.  I want to  eliminate the possibility of an incorrect profile.

If I re-sync when the SNRM is around 28/29 then it increases to 30+. If I re-sync when the SNRM is in low 20s then it increases to high 20s.

Currently (2.05pm) it's 29.9/14.0 so I will re-sync and post again.

[Oranged]

The only other thing to check is errors, as theses can come up affecting the speed without having any detriment to the snr/snrm.

on a fixed spped service you not have interleaved packets so the acceptable error rate will be much lower
over a 5 min period: errored seconds <15 , crc & hec errors <60-100 is ok 

Interleaved service crc & hec errors up to 1000 are ok, fec & rs errors up to 11000- 14500 are ok over the same period. 

It's worth bearing in mind the huge difference in acceptable errors between non interleaved & interleaved dsl, worth bearing in mind if any one's looking to turn interleaving off in order to get a bit more speed which would be proportionatly much smaller gain in comparison to the added venerability you'll get. If you lines always stable with very little in the way of errors, fine. If not worth thinking again 

Currently with interleave depth 32 up 8 down :-

Counters        Down            Up

SF:             15858232                15858230
SFErr:          0               1867
RS:             578825498               67397477
RSCorr:         1207            1227049
RSUnCorr:       0               0

HEC:            0               6226
OCD:            0               0
LCD:            0               0
Total Cells:    1376074251              -379150371
Data Cells:     7623194         17210590
Drop Cells:     0
Bit Errors:     0               329087

ES:             0               482
SES:            0               91
UAS:            28              1852

Total time = 1 days 23hours 47min 7sec
SF  = 31904995   CRC = 0
LOS = 0   LOF = 0   ES = 0

Latest 1 day time = 23hours 47min 7sec
SF  = 5278415   CRC = 0
LOS = 0   LOF = 0   ES = 0

Previous 1 day time = 24hours 0sec
SF  = 5325994   CRC = 0
LOS = 0   LOF = 0   ES = 0

[Oranged]

Re-sync at 2.15pm >>>>>


Downstream     Upstream
 
Data rate 2268  285 

Noise margin 30.4  33.9 

Output power 20.1  11.5 

Attenuation 41.0  19.7 

See the massive increase in upstream SNRM ?

Edit : just noticed downsteam RCO 30% (7592kbps) upstream RCO 30% (945kbps) this has changed from Post 1
 

[Oranged]

At 3.10pm I plugged into the test socket and the result >>>>>>>>

Downstream     Upstream

Data rate 2268  285 

Noise margin 31.4  36.4 

Output power 19.9  11.7 

Attenuation 40.5  19.5 

RCO down 29% (7816kbps) RCO up 30% (945kbps)
 

[kitz]

Data rate 2268  285

Noise margin 30.4  33.9 

That seems to show that your line is being rate limited to 2Mbps. (A fixed 2Mb account)
If you were on a "up to 8Mb" type account then the Noise Margin would be lower and the sync speed higher.
Your downstream is fine and shows no problems indicating that your line is capable of much higher speeds.
The (downstream) seems very good for a 41dB attenuation line.

just noticed downsteam RCO 30% (7592kbps)

Thats an indicatation of what your router estimates you line should be able to sync at based on the current conditions if it wasnt being rate limited somewhere.
Its normal for this figure to fluctuate slightly on each reboot as it will take into account the current SNR.


Now looking at your stats you dont appear to have any downstream problems but something is niggling me about your upstream.

In actual fact theres something very weird about your SNR compared to your attenuation - in that its VERY good for your supposed line length (as indicated by the atten)... too good.


As a comparison Im on a very short line and these are some stats from when I was on a 2Mb account.

Downstream
Connection 2272
Attenuation 7dB
Noise Margin 31dB

Upstream
Connection 288
Attenuation 4dB
Noise Margin 29dB

I would not expect a 43dB atten line to show similar (or better) stats than this line.
Just how close to the exchange are you? Can you put your phone no and postcode into the adsl line checker and report what it says about your distance.

Theres a few thoughts going through my head right now - but I need to know your approx distance from the exchange.

If your attenuation is vastly wrong for your line distance then it could show that theres a problem on the line... either that or somethings mis-reporting somewhere... or perhaps your internal wiring/filters.
This is separate to the indications that Orange appear to have you on a fixed 2Mb line...  but why would they do that?

[Oranged]

Distance:- Direct:    2.07 km
    (appx)* By Road: 4.02 km

As I said in my first post, I understand that Orange implemented ADSL2+ at my exchange around the time the problem started and I think that somehow this has affected my connection. I agree with you that it seems they have put me on a fixed 2Mb connection but being LLU surely this process is more or less automated.

Before this problem, I synced at 6656 with SNRM 10 - 13 and this had been a very stable connection since 25/05/2007.

I removed the ring wire back in May 2007 and have also replaced filters. I am currently connected by ethernet and plugged into the main BT linebox.

[kitz]

>> (appx)* By Road: 4.02 km

Thanks for the additional info. A 41dB line is about right for line length of around 3-4km. 
In view of the high SNRM I just wanted to make sure that you werent actually closer and had a line fault that materialed itself by showing a high attenuation.


>> I agree with you that it seems they have put me on a fixed 2Mb connection but being LLU surely this process is more or less automated.

It should be automated..  Theres no public info about how the Orange DLM process works, but in the case of BTs DLM, if you have a bout of severe errors, the DLM can transfer you automatically to a capped fixed rate service if it thinks it will improve your line.

Again I wanted to ensure that there was nothing strange going on in the background which could have made Orange's DLM to do so.  hence the question mark after my last post.


>> I removed the ring wire back in May 2007 and have also replaced filters. I am currently connected by ethernet and plugged into the main BT linebox.

These actions will have maximised your line potential which will in part explain the decent line stats.

I think the obvious course of action now is to approach Orange and tell them that you appear to be on a fixed 2Mb line - as indicated by the consistant 2268 sync and plenty of spare SNR Margin.

I'm still not 100% happy about some of the SNR fluctuations but once you arent restricted by the 2Mb fixed rate, then you will be in a much better situation to see what effect (if any) this is having on your line.

[Oranged]

Downstream
Connection 2272
Attenuation 7dB
Noise Margin 31dB

Upstream
Connection 288
Attenuation 4dB
Noise Margin 29dB

Sorry I forgot to comment on your 2Mb stats.

The data that is really puzzling me is that it's 2268/285.......surely a normal fixed 2Mb ADSL LLU would be as yours 2272/288 ?

[kitz]

Yes it should be with BT.. but with LLU the operators they are free to choose their own parameters. 
Many of them do differ slightly from the traditional values that we know with BTWholesale .. with Sky being about the lowest and offering a measly 2000 for their "2Mb profile" when compared to the 2272 of BT.

BT includes the additional to allow for such things as TCP/IP/ATM overheads etc. 

[Oranged]

I didn't check the stats until late last night.

Upstream SNRM was an amazing 1.2 at 1am this morning and at 9am this morning was still downstream = 25.5 upstream = 1.3, attenuation = 40.5/19.6.

But as soon as I hit the refresh button in DMT, SNRM moved to 30.3/17.1, attenuation 41.0/20.3