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Strange DSL Behaviour

Discussion in 'Networking' started by dranjam, Jan 27, 2007.

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  1. dranjam

    dranjam Thread Starter

    Joined:
    Jan 27, 2007
    Messages:
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    Hello.

    I am using UK's BT Broadband, and it wasnt' working very well till last days, but it was ok, now it changed into a nightmare.

    1. My router stats:
    Code:
    	Showtime Firmware Version:	3.24
    	Line State:	SHOWTIME
    	Modulation:	G.dmt
    	Annex Mode:	ANNEX_A
    	Startup Attempts:	1
    	Max Tx Power:	-38 dBm/Hz
    	CO Vendor:	TEXAS_INSTRUMENTS
    	Elaspsed Time:	0 days 2 hours 16 minutes 7 seconds
    
    Downstream Upstream
    	
    SNR Margin	11.3	21.0	dB
    Line Attenuation	60.5	31.5	dB
    Errored Seconds	2603	68	<----- What's this?
    Loss of Signal	0	0	
    Loss of Frame	0	0	
    CRC Errors	5282	68	  <---- What's this?
    Data Rate	576	288	kbps
    Latency	FAST	FAST	
    
    I had this kind of stats for months, but it wasn't working very bad, it was dropping connection couple of times a day, it was annoying but I could live with it. Up to a certain limit.... What might be the reason for this? I have conexant router and I've heard it's not very good, should I change it?

    2. It all went worse yesterday
    I didn't change any settings, didn't install any new hardware or soft, but now transfer rate is at 5kb/s. I checked for viruses with Avast (result: PC was clean), I checked for rootkits with BlackLight (result: PC was clean) I am also checking it with Windows Defender atm (nothing so far). I use Windows Firewall. Pings are slow, 1000ms to most popular sites on average.

    After I turn the router off for 30 seconds and turn it back on, connection is good for 1-3 minutes, then it goes slow again. It also goes fast again (for 20-30 minutes) every now and then without any action from my side. I have 2 PCs in my network, 1 wireless and 1 ethernet, both have this problem.

    Writing fast connection I mean 400-450 kbps, by slow connection I mean 20-30 kbps.

    Okz, I hope the info I am giving is enough to make a clear view, let me know and I will provide further details.
    Thanks in advance :).

    EDIT: BT online tools cannot check my line, gentelmen from the helpdesk said the line is ok (but I don't trust him too much :p).
     
  2. MMJ

    MMJ Guest

    Joined:
    Oct 15, 2006
    Messages:
    3,625
    What is the speed you signed up to?

    Did you contact you isp?

    Did you try the internet on another computer?

    Good trouble shooting, btw. ;)
     
  3. 1002richards

    1002richards Retired Trusted Advisor

    Joined:
    Jan 29, 2006
    Messages:
    5,333
    Hi,
    We had poor connection with BT b/band. Called out the engineer ( no charge) he made some changes at a "junction box" a few yards up the road from my house and all now works fine!
    (Of course it will all go t*ts up now I've said that!!!)

    Good luck
    Richard
     
  4. O111111O

    O111111O

    Joined:
    Aug 26, 2005
    Messages:
    894
    Downstream Upstream

    Errored Seconds 2603 68 <----- What's this?

    CRC Errors 5282 68 <---- What's this?


    Errored Seconds is exactly that, since the router last had it's stats reset (or power cycled) the router has seen 2603 errored seconds FROM the DSLAM. An errored second is a value that counts how long the SNR is too high for the xDSL interface to actually decode a modulated signal.

    CRC errors are a bit higher layer, these are frames received that didn't pass layer 2 header cyclic redundancy checks. So, the xDSL could decode the modulated signal, but the frame it decoded didn't make sense as a packet.

    To sum it up, your modem has poor signal to noise (11db) downstream from the DSLAM to your modem. It's low enough that your modem can't decode frames (summing up to 45 minutes of outage). This translates into extremely poor performance.
     
  5. TerryNet

    TerryNet Moderator

    Joined:
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    Messages:
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    First Name:
    Terry
    So, what do you do about 01111110's last paragraph? First, thank him!

    Second, check all your connections and wires that you can from your modem back to outside. I'd remove any jacks I can reach and reconnect them. Make sure you have only one splitter in the DSL line. Make sure you have filters on all phones, answering machines, faxes, etc.

    Third, ask (nicely at first) your ISP to check their lines and give them the signal to noise data.
     
  6. dranjam

    dranjam Thread Starter

    Joined:
    Jan 27, 2007
    Messages:
    4
    Thank you everyone, this is a lot more than I expected :).
    Maybe my english is not good enough to comprehend 01111110's post - is it my routers fault or DSLAM is just too far (which is possible, as I live on outskirts of town) ?
    I will try contacting ISP again, but when I tried this before the gentelman on the line seemed to know even less than myself about errored seconds... Maybe it just takes some luck :>.

    Hmmz, I just recalled. Is there any logical explanation in drop in connection speeds from ~450 kbps, as it used to be 2 days ago, to ~100 kbps as it is now? Maybe just maintanance work at exchange point or ... ?
     
  7. TerryNet

    TerryNet Moderator

    Joined:
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    Messages:
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    First Name:
    Terry
    Distance is a DSL problem, but unless you moved farther away in the last couple days it doesn't explain the 450 -> 100 drop. :)

    If 450 kbps is a lot less than you are supposed to be getting, then distance is a possible problem. As far as what has caused the drop, it could be the modem failing but is more likely a cable/wire, connection or filter failing.

    In addition to my previous suggestions, disconnect all phones, etc., and see if there is any difference. If your 450 Kbps comes back, then start adding phones back one at a time until you find the filter that failed.

    After you've eliminated your own wiring and equipment as possible problems, just tell your ISP how your speed has dropped, you've been advised by an expert that the signal to noise ratio is bad, and please check the line and their modem.

    I think that a sudden change like you experienced is often because of an overhead wire becoming loose or a buried cable getting wet or chewed.
     
  8. TerryNet

    TerryNet Moderator

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    First Name:
    Terry
    Forgot that you had a router. Obviously the first thing to check is what happens when you connect a computer directly to the modem.
     
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