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Title says it all. For a bit more info though:

Basically, I have Time Warner cable internet. My speeds maintain a stable 2Mbit/s upload and 20Mbit/s download with average ping times around 30ms.

This crazy thing happens though when I upload anything. I went to upload a 200M file to my server today through sftp and my internet completely choked up. I speed tested it during this upload and my ping time was around 800ms, download speeds of 0.2Mbit/s and Upload speeds of 0.3Mbit/s. Note, I wasn't downloading anything during this time either. It is just straight upload.

What is it that causes this phenomenon? My router is OpenBSD. Is there anything I could set up to fix this problem(by queues or some such), or is this a problem with cable internet?

Earlz
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3 Answers3

4

You ran a speed test whilst uploading. The upload then showed 0.3 mbit/s. I assime your file upload speed to the server was somewhere near (2 mbit/s - 0.3 mbit/s), right? As jjlin saus: downloading also needs uploading. Limit the upload speed to your server (sftp -l) for example to 1.5 mbit/s and then see if your downloads run smoothly again when you are uploading.

Vincent
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3

I run OpenBSD on my egress device at home and have had this addressed for quite a while. I recommend you read about this well-known phenomenon at https://web.archive.org/web/20120923235002/http://www.benzedrine.cx/ackpri.html for more information on how to address this using pf (the author is the original developer of pf).

Bink
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1

Another thing to keep in mind is that service providers use a number of techniques to keep residential users from operating commercial servers on their connections. One technique is to monitor the aggregate upload megabytes over a few minutes, and, if it's high, start to "choke" the connection.

So a medium-sized upload may run fairly fast, but a larger one will slow down and also slow down the download rate with it.

Daniel R Hicks
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