The Old Dlink 2500u

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slvR

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Greetings gents,

I recently picked up a Dlink 2500u, it's working well and all but I seem to notice disconnects frequently. It may be related to my upstream snr being borderline stable.
Does anyone know of any firmware mods/changes I can make that could improve stability? Even by a few percentage?
As these are cheap I don't really mind doing something that could cause long term degradation on the modem as it's really just a transparent bridge atm.


All feedback is welcome,
Thanks
Mike
 
Post your stats. Here are mine: I manually set target snr to achieve this. It runs stable

Code: 
Mode: 	ADSL2 
Type: 	Fast 
Line Coding: 	Trellis On 
Status: 	No Defect 
Link Power State: 	L0 
 
  	Downstream 	Upstream
SNR Margin (dB): 	5.4  	13.1 
Attenuation (dB): 	62.5  	33.6 
Output Power (dBm): 	0.0  	7.7 
Attainable Rate (Kbps): 	5408  	896 
Rate (Kbps): 	3511  	507 
MSGc (number of bytes in overhead channel message): 	59  	12 
B (number of bytes in Mux Data Frame): 	109  	15 
M (number of Mux Data Frames in FEC Data Frame): 	1  	1 
T (Mux Data Frames over sync bytes): 	1  	4 
R (number of check bytes in FEC Data Frame): 	0  	0 
S (ratio of FEC over PMD Data Frame length): 	0.9932  	0.9922 
L (number of bits in PMD Data Frame): 	886  	129 
D (interleaver depth): 	1  	1 
Delay (msec): 	0  	0 
 
Super Frames: 	2446605  	2322773 
Super Frame Errors: 	223339  	0 
RS Words: 	0  	0 
RS Correctable Errors: 	0  	0 
RS Uncorrectable Errors: 	0  	N/A 
 
HEC Errors: 	210878  	0 
OCD Errors: 	14423  	0 
LCD Errors: 	2  	0 
Total Cells: 	326186695  	485369 
Data Cells: 	285961443  	165317 
Bit Errors: 	0  	0 
 
Total ES: 	37640  	0 
Total SES: 	0  	0 
Total UAS: 	30  	0
 
Downstream Upstream
Line Coding(Trellis):
SNR Margin : 13.2 8.0
Attenuation : 15.5 12.0
Output Power : 12.0 12.4
Attainable Rate (Kbps): 21852 1096
Click to expand...

Noticing it jump a lot. Upstream is around 7.3-10dB and just wont sit still.....
how did you set a target SNR?
Anyway to lower the lowest acceptable SNR the modem will sync at? May not work but worth a try.
 
Last edited:
Mode: ADSL2+
Type: Fast
Line Coding: Trellis On
Status: No Defect
Link Power State: L0

Downstream Upstream
SNR Margin (dB): 13.1 7.3
Attenuation (dB): 18.0 8.0
Output Power (dBm): -3.0 12.8
Attainable Rate (Kbps): 22220 1072
Rate (Kbps): 10015 1023
MSGc (number of bytes in overhead channel message): 75 12
B (number of bytes in Mux Data Frame): 250 31
M (number of Mux Data Frames in FEC Data Frame): 1 1
T (Mux Data Frames over sync bytes): 1 4
R (number of check bytes in FEC Data Frame): 0 0
S (ratio of FEC over PMD Data Frame length): 0.7987 0.9922
L (number of bits in PMD Data Frame): 2514 258
D (interleaver depth): 1 1
Delay (msec): 0 0
Click to expand...

Just checked again.
 
You can define how it should handle the SNR through telnet, but unfortunately that will only affect your downstream
 
March 16
9:15pm
196.210.196.xx
SNR Margin (dB): 13.1 7.2
Attenuation (dB): 18.0 8.0

March 16
10:26pm
196.210.196.xx
SNR Margin (dB): 11.8 7.0
Attenuation (dB): 18.0 8.0

March 17
2:55pm
196.210.144.xx
SNR Margin (dB): 12.1 7.8
Attenuation (dB): 18.0 8.0

Not sure why it jumps this much :/
 
Woodlands said:
March 16
9:15pm
196.210.196.xx
SNR Margin (dB): 13.1 7.2
Attenuation (dB): 18.0 8.0

March 16
10:26pm
196.210.196.xx
SNR Margin (dB): 11.8 7.0
Attenuation (dB): 18.0 8.0

March 17
2:55pm
196.210.144.xx
SNR Margin (dB): 12.1 7.8
Attenuation (dB): 18.0 8.0

Not sure why it jumps this much :/
Click to expand...
That's not much fluctuation for the SNR value - unfortunately your average margin is just very close to the sync threshold

Unlike Attenuation (typically constant as it is based on loop distance / copper resistance), SNR can be way more dynamic - fluctuations of 1-4 dB as you've demonstrated, can be considered completely normal

You should only be concerned about SNR fluctuations in a situation where your normal range may for example be 20+ dB, yet suddenly your modem drops sync because the SNR somehow dropped below the threshold of about 6 dB. In that case, something would be inducing harmful interference on the line

Often an effective way to diagnose heavily fluctuating SNR values is to literally pick up a phone that is connected to the same line, as soon as you notice the fluctuations - you will then usually either hear something like a crossed line, or scratching/cracking which could be a loose joint or water reaching the joints and causing a short circuit

There are a few things you can do to improve sync rate / SNR margins yourself, such as converting over your portion of phone line (from inside to the pole outside) into a twisted-pair copper connection (cat5 works great), using quality POTS filters, and removing unnecessary devices from the phone line (even if you just do so temporarily to assess the difference). Unfortunately there is only so much improvement you can do though before you're at the mercy of Telkom's best-effort infrastructure
 
Last edited:
My SNR used to be over 12dB not too long ago. The recent 2 week rain started about the same time as the lower SNR, but at the same time I see Telkom bukkies all over the area installing orange cabling. Could be any one of those reasons or just damn bad luck.
Is there anything I could do on the modem side to increase SNR? I might just have Telkom over and have the line checked and moved somewhere without any interference of any sort.

Thanks for the help!
 
Woodlands said:
Greetings gents,

I recently picked up a Dlink 2500u, it's working well and all but I seem to notice disconnects frequently. It may be related to my upstream snr being borderline stable.
Does anyone know of any firmware mods/changes I can make that could improve stability? Even by a few percentage?
Click to expand...

I use the same modem to which is attached a TP-Link Wi-Fi router.
Please refer to this thread http://mybroadband.co.za/vb/showthr...pped-bolt-on-feedback?p=12222666#post12222666 - I experienced the same problem for weeks, with disconnects a few times a day.

In the last 5 days, I've not had one disconnect, so I now think either Telkom or the ISP (Vox) did something to sort it out, behind the scenes. I wouldn't think it's the modem - my Attenuation is over 50 as you'll see in the post, and now things have settled, all seems stable again.

You might want to contact D-Link (where you are in PTA) to e-mail the latest firmware. Obviously need to be specific about the modem ref no. Think you simply unzip the file + run it with modem on, from what I remember last time they sent it to me ? (Thinking of contacting them again to send the latest again.)
Can phone Support no. : http://www.d-link.co.za/corporate/contact/
 
Flashed new firmware.
Let's see what happens.
 
Today


March 18
2:51pm
196.215.79.xx
SNR Margin (dB): 14.0 9.1
Attenuation (dB): 18.0 8.5
 
10 seconds ago
SNR Margin (dB): 20.8 6.0
Attenuation (dB): 16.0 7.5
Output Power (dBm): 15.3 12.4
Attainable Rate (Kbps): 11936 1164
 
back from school

Line Coding(Trellis): On On
SNR Margin (0.1 dB): 169 91
Attenuation (0.1 dB): 150 118
Output Power (0.1 dBm): 118 124
Attainable Rate (Kbps): 24852 1128
 
SNR Margin (dB): 12.6 7.6
Attenuation (dB): 18.0 8.5
Output Power (dBm): -2.9 12.8
Attainable Rate (Kbps): 21796 1076
Rate (Kbps): 10239 1023

nope
 
in my experience I would report a line fault if all the first line support steps have been done, those SNR values are moving around way too much.

first line support steps:

test at the main/master socket with a single pc connected via Ethernet cable directly to the modem/router. make sure you are using the pots filter correctly and all other devices unplugged from any other phone sockets on the premises.

try another working pots filter and try another telephone/adsl cable. if you can, try another modem/router.

if the problem persists, call Telkom and tell them you are experiencing frequent disconnects and you see your SNR values jumping around. (to me sounds/looks like a light short and/or earth contact)
 
I've done all of the above. Fault was logged on the 10th
No feedback as yet.



access said:
in my experience I would report a line fault if all the first line support steps have been done, those SNR values are moving around way too much.

first line support steps:

test at the main/master socket with a single pc connected via Ethernet cable directly to the modem/router. make sure you are using the pots filter correctly and all other devices unplugged from any other phone sockets on the premises.

try another working pots filter and try another telephone/adsl cable. if you can, try another modem/router.

if the problem persists, call Telkom and tell them you are experiencing frequent disconnects and you see your SNR values jumping around. (to me sounds/looks like a light short and/or earth contact)
Click to expand...
 
Line Coding(Trellis): On On
SNR Margin (0.1 dB): 153 90
Attenuation (0.1 dB): 150 115
Output Power (0.1 dBm): 115 128
Attainable Rate (Kbps): 24872 1116
Click to expand...

just now
 
Hmm... odd the SNR bouncing that much.

Have you phoned the call centre and asked to reset the port? (A quick way to do so is call 10210, navigate to dsl and then press numbers not in the list which puts you in the front for a consultant. Say your ISP suggested you do a port reset.)
 
Did this already.


agentrfr said:
Hmm... odd the SNR bouncing that much.

Have you phoned the call centre and asked to reset the port? (A quick way to do so is call 10210, navigate to dsl and then press numbers not in the list which puts you in the front for a consultant. Say your ISP suggested you do a port reset.)
Click to expand...
 
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