![]() All of the runs were made late at night to minimize any real-time issues with congestion or other factors that would affect speeds (or connections) adversely. So although I'm using my own CT and ST speed tests for illustration, the data set is much larger. The data set includes every test run by myself and others over the past several months from multiple locations in various states around the US. I remember when I had cable internet back in 2000-2003 and my connection speeds were limited to 7 Mbps/1.5 Mbps down/up (no more than 1.5 MBps upload) despite paying $60 per month! ![]() (4) In addition to those issues above with TCP congestion control algorithms which are applied in all other major consumer ISP's, CT also has an additional choke point in the network where all uploads from residential customers are throttled to around 5 Mbps, no matter how much bandwidth is available.Īlthough CT has been applied only to Comcast customers for the past couple of years, other major ISPs have used similar controls on their networks for many years prior to that, so this is not a new practice. So even though your internet speeds say 70+ down/10 up or whatever, CT caps download and/or upload speed at around 30 Mpbs in most locations. This is a serious limitation, since it means that on a 100 Mbps connection, you will only be able to download at 50 Mbps max and upload at 25 Mbps max. (3) CT will not use more than half of your connection speed for downloads and uploads combined. The ST MTU is 1500 by default, but can be changed to 1480 if you want to get the best transfer rate possible (in some cases). When the congestion window reaches a preset limit (3 times that of an uncongested connection), then it stays at that limit for additional losses or until congestion goes away. The default is 30 seconds when there are packet losses. If there is no packet loss, the timer typically increases by 1 every 10 seconds. This is a timer which starts at around 5 seconds and increases in 10 second increments for each packet loss after that. That should give us some idea about how much variation (spread) there is from the norm. Not just my speed, but many other people's speeds who have reported to various internet forums, particularly. We will look at the relative speeds of CT and ST in multiple locations around the US. CT is virtually always slower than ST by a factor of 2 to 5, sometimes even as high as 10 in some locations therefore CT should not be used for estimation of internet speeds but only for troubleshooting purposes when there is a problem.
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