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3 Messages
Slow Internet Speed/Increased latency after I exceed 2 Mbps upload.
I CTest my internet speed at around 20 Mbps download and 20 Mbps upload with a 30 ms latency, but recently I have been having a problem with my internet connection if I do a sustained upload above 2 Mbps. I can upload a large file to FTP or Dropbox or any other format as as soon as I reach above 2 Mbps my download speed drops to anywhere from 1 to 2 Mbps and the upload drops to around 300 Kbps. The latency also jumps to around 300 to 500 ms.
I have the Motorola SB6120 SURFboard DOCSIS 3.0 and the issue happens when I am connected directly to the modem or through a wireless router and with my PC and my laptop. I have swapped the cables, I have called technical support (no issues on their end), I have had the cable technicians out to my house (they found no problems with the line). I have not used all my bandwidth and technical support says that I am not being throttled. The cable guys says that everything looks fine using CTest with no load and that is all they can do because that is the standard test. They cannot load their test equipment and they have no method of escalating this issue to advanced support. They said if cTest shows no problem with no load, this is all they can do. I need a method of moving this issues up to advanced support because it seems to be an issue with the CIMS or some backroom equipment on the COX side. I don't do a lot of uploading, but when I do it is a pain to have my internet effectively crash over 2 Mbps. Help!? Has anyone else had this issue?
Thanks.
divilspawn
New Contributor
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16 Messages
13 years ago
The issue you are experiencing is merely the enforcement of your paid bandwidth limit. Speed tests are completely unreliable for anything more than a quick check while nothing else is happening on the network to verify things appear normal.
When you are sustaining an upload at your limit, the cox equipment is transmitting data first in first out. How the cox equipment enforces that limit is to queue the data to make sure you do not exceed your limit. As the software on your computer does not know of this limit it continues to attempt to upload as fast as it can; this results in the queue/buffer filling up and the excess data being thrown away. As data is thrown away computers know they are missing information and request that the data be resent, or know they should have gotten a response and retry since they didn't get a response. This adds to the congestion and causes the problem to cascade.
When you are attempting to download data, your computer has to acknowledge that it has received the data. If those acknowledgements do not go through then you cannot receive more data until you retry your acknowledgement.
As such, all equipment on both sides is working properly.
The best method for you to get a better end user experience is to limit your sustained upload to 1-1.5Mbps on your computer. This will prevent the computer from saturating the network and in turn leave enough bandwidth for you to continue utilizing other applications.
Hopefully this helps to clarify the issue for you,
divilspawn
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