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Thread: Download speeds drop from 1520kbps to 14kbps when uploading

  1. #1

    Download speeds drop from 1520kbps to 14kbps when uploading


    I'm having problems with Charter Pipeline in Central Michigan. Shortly after I begin an upload, about 10-15 seconds, my download speed drops dramatically.

    I'm running a home network with 3 computers on it; I'm using a D-Link 707 sharing router to connect the network to the internet. All of the PCs are running Windows XP Professional, two without service pack 1, one with it.

    This is something that just started happening about two weeks ago; but I didn't draw the connection between upload speeds adversely affecting the download speeds until last Thursday or Friday.

    As an example of what happens I did five speed tests, 4 of them without doing an upload.

    Results (download/upload in kbps)


    At this time I also did a trace route to my webhost and get acceptable values, all values between 11 and 88 ms (avg 51ms)

    Next I proceeded to upload a 2MB file to my webhost. The upload starts at 32KB/s and gradually works its way down to 12-14KB/s

    Now I run another test:


    A traceroute shows that the first jump from my router/my computer to their network with ping times averaging 3560ms

    Yes folks, worse than a 56K modem

    I've called Charter a few times on the matter and they tell me that everything looks fine from their end and that the problem is with my computer.

    I'm having a hard time believing that because if I'm uploading something my son also sees the same problems on his computer, and vice versa. We see the same problem either connecting through the router or connecting directly to the cable modem.

    Does anyone have any ideas as to what could be wrong? Is Charter telling me a flat-out lie? Is there something wrong with my modem?



  2. #2
    Dr Tweak mnosteele52's Avatar
    Join Date
    Jul 2001
    Chesapeake, VA
    I have seen this type of problem with DLink routers in the past, try connecting each one of the pc's to the cable modem one by one bypassing the router and see if the problem occurs, if it doesn't then most likely it's the router. I suggest try a Linksys router if you get a new one.

  3. #3
    Thanks for replying.
    Here's a breakdown on the speeds I get from the DSLReports speed test:

    TBird 800
    thru router 1515/125
    thru router while uploading 11/33
    direct to modem 1472/124
    direct to modem while uploading 15/24

    TBird 1ghz
    thru router 1410/128
    thru router while uploading 247/67
    direct to modem 1483/118
    direct to modem while uploading 193/67

    Duron 800
    thru router 1482/123
    thru router while uploading 12/23
    Can't easily hook this one direct to modem.



  4. #4
    Dr Tweak mnosteele52's Avatar
    Join Date
    Jul 2001
    Chesapeake, VA
    Thanks for replying back... doesn't appear to be the router. Atleast you have eliminated that as the culprit. Have you tweaked the TCP/IP settings in your computers or are you running defaults? Make sure all the NIC duplex settings are set to 100mb full duplex mode, make sure you have the latest firmware for your router. We'll figure this out....... just basic troubleshooting.

  5. #5
    SG Enthusiast
    Join Date
    Jun 2000
    Columbus, Ohio
    Your modem's fine.

    Your router's fine.

    This is normal behavior, built into the TCP/IP protocol by design.

    Each packet must be acknowledged. The acknowledgements for your downstream traffic are stuck in the upstream queue produced by the upload. In general, when you upload at the circuit capactiy, the downstream slows to the same speed as the upload.


  6. #6
    Regular Member Fudgemaker's Avatar
    Join Date
    Mar 2002
    Wellesley, Massachusetts
    if you are uploading at the same time you are attempting to take a speed test... then of course your values are going to slow down considerably like you've shown to us. Speed tests should be taken with only 1 window browser open and nothing else going on at the same time.
    -I know where there's a good party. They've got liquor in the front and poker in the rear-


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