ADSL line dropping sync speed

[AndyHiggins]

Hello,

I have a Telkom ADSL line (with bandwidth through Telkom Intenet). I recently upgraded from 1Mbs to 4Mbs (currently the maximum for my area).

Lately if I look at my modem admin web page it shows over time (normally a matter of hours) a deterioration in the speed at which the modem is synced. If I reboot the modem it normally syncs at 4096 Kbps for the down link but after some time it gradually degrades e.g. now it shows "Line Rate - Downstream (Kbps): 1056". The uplink speed stays fairly stable but also degrades slightly e.g. from 356 Kbps to 352 Kbps.

Any ideas what the likely problem is? Could it be noise on my Telkom line? If so, what is the best way to go about fixing this?

Thank you.

[Keegan]

something’s that happens when you are to far from the exchange, Best thing to do is call them and ask them to stabilize your line.
However a few weeks later you will experience the same thing, basically nothing you can do until the exchange is upgraded or move back to 1024 for stability.

[XperiAnce]

Post your SNR and Attenuation - also, post a traceroute to a local and international site.

[AndyHiggins]

Thanks for the response. Following is some additional output from my modem:


Statistics -- ADSL

Mode: G.DMT
Type: Fast
Line Coding: Trellis On
Status: No Defect
Link Power State: L0

Downstream Upstream
SNR Margin (dB): 9.1 7.0
Attenuation (dB): 55.0 27.5
Output Power (dBm): 12.3 19.7
Attainable Rate (Kbps): 4928 452
Rate (Kbps): 4096 352
K (number of bytes in DMT frame): 129 12
R (number of check bytes in RS code word): 0 0
S (RS code word size in DMT frame): 1 1
D (interleaver depth): 1 1
Delay (msec): 0 0

Super Frames: 277594 277593
Super Frame Errors: 4579 0
RS Words: 0 0
RS Correctable Errors: 0 0
RS Uncorrectable Errors: 0 N/A

HEC Errors: 4026 0
OCD Errors: 91 0
LCD Errors: 0 0
Total Cells: 45570084 0
Data Cells: 416105 0
Bit Errors: 0 0

Total ES: 920 0
Total SES: 44 0
Total UAS: 11 0

It is back up to 4096Kbps now as I have just rebooted the modem.

[XperiAnce]

This might be your problem here:
SNR Margin (dB): 9.1 7.0

Using this post as a guide:

SNR:
6dB or below is very bad and will experience no synch or intermittent synch problems
7dB-10dB is fair but does not leave much room for variances in conditions
11dB-20dB is good with little or no sync problems
20dB-28dB is excellent
29dB or above is outstanding

[hereticangel]

Attenuation (dB): 55.0 27.5

you stay pretty far from exchange

[AndyHiggins]

Thanks for the help.

Btw, I found that is I unplug my phone from the line the SNR goes from 9.1db up to 13.7db (better) and the attenuation goes down slight from 55.0db to 51.0 db (better). I plugged the phone in and out a few times and this seems consistent so I guess I am going to leave the phone unplugged for a while and see if the line is more stable (pity I still have to pay Telkom for line rental).

Also, with the phone unplugged the upstream rate goes up to 512kbps (up from 352Kbps).

[TonyA]

Have you tried switching the setting on the modem from ADSL to ADSL+

[XperiAnce]

Thanks for the help.

Btw, I found that is I unplug my phone from the line the SNR goes from 9.1db up to 13.7db (better) and the attenuation goes down slight from 55.0db to 51.0 db (better). I plugged the phone in and out a few times and this seems consistent so I guess I am going to leave the phone unplugged for a while and see if the line is more stable (pity I still have to pay Telkom for line rental).

Also, with the phone unplugged the upstream rate goes up to 512kbps (up from 352Kbps).

Have you got POTS filters on your phones?
POTS Filter: http://www.linkqage.co.za/images/NET...SL008E1_BG.jpg

[AndyHiggins]

Have you got POTS filters on your phones?
POTS Filter: http://www.linkqage.co.za/images/NET...SL008E1_BG.jpg

I do have a pots filter for the phone (when I unplug the phone getting the better performance I also unplug the pots filter).

[AndyHiggins]

Have you tried switching the setting on the modem from ADSL to ADSL+

I have a D-Link modem:

BoardID: DSL-2640U
Software Version: RU_2.00
Bootloader (CFE) Version: 1.0.37-12.1
Release Date: Tue Aug 25 15:02:49 CST 2009
Wireless Driver Version: 4.174.64.19.cpe1.0sd

I can't find a setting to set it to ADSL+ ?

[FNfal]

Mode:G.DMT = the DSLAM you are on (old one )
ADSL2+ = new DSLAM (IMAX)
You cannot change it ,you are on an old DSLAM (interestingly they seem more tolerant to bad line conditions than the new IMAX)

[gregmcc]

Attenuation (dB): 55.0 27.5

you stay pretty far from exchange

I beat that:
DS Line Attenuation 63

I'm sure I dont stay that far from the exchange though.