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2820 slow performance

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05 Nov 2009 15:30 #1 by vimto
2820 slow performance was created by vimto
Hi,

I got a 2820 to replace my Netgear ADSL modem + Airport Extreme. However after switching my downloads have dropped from 360 kBps to 30 kBps. I have disable the QOS, but that didn't help. Any other ideas on what I should disable, or how I can diagnose the issue.

If I plug my netgear/airport extreme back in using the same cables as the 2820, the downloads go back to 360kBps, so I don't think it's a cable issue. I flashed the firmware to 3.3.3, could that be an issue?

ADSL Status Mode State Up Speed Down Speed SNR Margin Loop Att.
ADSL2(G.992.3) SHOWTIME 530000 264000 27 37

Thanks

Kamran

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05 Nov 2009 17:33 #2 by nrb501
Replied by nrb501 on topic 2820 slow performance
Could you post the stats from your Netgear for comparison. The SNR reported by the Draytek looks suspiciously high and the download speed is low at only 264Kbits
Which version of the 3.3.3 firmware did you use, the one with modem code Annex A 232201 usually works best. Also what is the modulation setting on the Draytek (in the WAN/Internet Access/WAN1 page)?
Can you also log into your Draytek via telnet (password is the same as for the web logon) and post the output of the command "adsl status".

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05 Nov 2009 17:42 #3 by vimto
Replied by vimto on topic 2820 slow performance
I don't really have stats from my netgear other than that the NAS is downloading at 360kBps from newsgroups, but the draytek is only getting ~30.

The modulation setting is multimode

Here are the settings from adsl status

adsl status


ATU-R Info (hw: annex A, f/w: annex A)

Running Mode : ADSL2(G.992.3) State : SHOWTIME
DS Actual Rate : 316000 bps US Actual Rate : 588000 bps
DS Attainable Rate : 3288000 bps US Attainable Rate : 588000 bps
DS Path Mode : Interleave US Path Mode : Interleave
DS Interleave Depth : 4 US Interleave Depth : 8
NE Current Attenuation : 36 dB Cur SNR Margin : 30 dB
DS actual PSD : 15. 8 dB US actual PSD : 11. 4 dB
ADSL Firmware Version : 211011_A

ATU-C Info

Far Current Attenuation : 22 dB Far SNR Margin : 6 dB
CO ITU Version[0] : 00004946 CO ITU Version[1] : 0000544e
DSLAM CHIPSET VENDOR : < IFTN >

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05 Nov 2009 17:52 #4 by vimto
Replied by vimto on topic 2820 slow performance
and here's the adsl status from 232201 like you suggested, whcih still hasn't changed the download speed

adsl status

ATU-R Info (hw: annex A, f/w: annex A)

Running Mode : ADSL2(G.992.3) State : SHOWTIME
DS Actual Rate : 272000 bps US Actual Rate : 419000 bps
DS Attainable Rate : 4152000 bps US Attainable Rate : 420000 bps
DS Path Mode : Interleave US Path Mode : Interleave
DS Interleave Depth : 4 US Interleave Depth : 8
NE Current Attenuation : 36 dB Cur SNR Margin : 27 dB
DS actual PSD : 15. 8 dB US actual PSD : 12. 6 dB
ADSL Firmware Version : 232201_A

ATU-C Info

Far Current Attenuation : 21 dB Far SNR Margin : 6 dB
CO ITU Version[0] : 00004946 CO ITU Version[1] : 0000544e
DSLAM CHIPSET VENDOR : < IFTN >

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05 Nov 2009 18:06 #5 by vimto
Replied by vimto on topic 2820 slow performance
Managed to get statistics from my Netgear

Line Mode ADSL2 Line State Show Time
Line Power State L0 Line Up Time 00:00:02:17
Line Coding Trellis On Line Up Count 1

Statistics Downstream Upstream
Line Rate 3732 Kbps 922 Kbps
Attainable Line Rate 4660 Kbps 924 Kbps
Noise Margin 6.1 dB 6.0 dB
Line Attenuation 38.5 dB 21.6 dB
Output Power 0.0 dBm 12.9 dBm
MSGC (number of bytes in overhead channel message) 62 11
B (number of bytes in Mux Data Frame) 111 122
M (number of Mux Data Frames in FEC Data Frame) 2 2
T (Mux Data Frames over sync bytes) 1 1
R (number of check bytes in FEC Data Frame) 12 8
S (ratio of FEC over PMD Data Frame length) 1.9032 8.4667
L (number of bits in PMD Data Frame) 992 240
D (interleave depth) 32 8
Delay 15 16
Super Frames 8430 8428
Super Frame Errors 0 0
RS Words 286650 286552
RS Correctable Errors 22702 0
RS Uncorrectable Errors 0 0
HEC Errors 0 0
OCD Errors 0 0
LCD Errors 0 0
Total Cells 1200988 203880
Data Cells 158 197
Bit Errors 0 0
Total ES 0 0
Total SES 0 0
Total UAS 51 0

Thanks for your help

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05 Nov 2009 19:30 #6 by nrb501
Replied by nrb501 on topic 2820 slow performance
It looks as though for some reason the Draytek/DSLAM are not negotiating a sensible line speed, this will probably require intervention by your ISP - depending on who that is that may be easy or not... BT's 21CN does seem to have a very variable success rate depending on customer hardware /DSLAM combinations.
Try setting the modulation type to G.DMT or ADSL2+ and see what happens, it may or may not work but that depends on how the DSLM is configured.
Hopefully someone else may be able to suggest other courses of action.
You may like to try posting on thinkbroadband.com but the quality of advice can vary somewhat.

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