We are interested in validating/comparing the PingER derived throughputs with those obtained by the Ookla Speed test measurements. I therefore contacted Ookla by email on November 27, 2007 and they Mike Apgar and Doug Suttles of Ookla were kind enough to reply, answer questions, and on December 6, 2007 , and provide data suitable for importing into Excel (CSV format) and analyzing.
Ookla maintains a fleet of speed-testing servers all over the world. A user chosen server downloads a file of incompressible data to the user's clinet client and then uploads it. They calculate the throughput by knowing the amount of data transferred and then dividing this by the time taken to transfer the data in each direction. A summary of this data is provided to the client user in real-time showing average download speed, upload speed, and ping time, which is the time it takes, in milliseconds, to send a packet of data from the server to the client computer and backRound Trip Time (RTT).
The data is also archived together with the location of the client. This is s determined based on the client IP address. Speedtest.net uses GeoIP databases from MaxMind to position the client and by default locate the closest server since the transfer speed depends on the TCP window and it TCP is not usually optimized for increased Round Trip Time ( RTT). While the information in MaxMind's GeoIP databases is very accurate, it is not perfect. More information on Ookla's speed test can be found here.
Ookla then uses the 95th percentile speeds for the IP address of each client. This way if a connection speed improves over time (or a better testing server for the region is added), it will improve the overall results. The same can be said for degradation of speed. These 95th percentile speeds are then what are averaged to determine the speeds shown in their data set. The ip_addresses column is the number of unique IP addresses from a specific country that have taken a test at Speedtest.net. The file provided contained aggregated data with one line for each country. It included data from 174 countries. The columns contained: the Top Level Domain, the Country name, the number of IP addresses, the average donload speed in kbits/s, the average upload speed in kbits/s. The data for each country was from >= 100 IP addresses.
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A comparison of the Ookla upload versus download throughput speeds is seen below on the left. In all cases the download exceeds the upload speed. The best value for the ratio of up/down is 80% (Azerbaijan). the The worst is 9% (Portugal), the median is 34% +- 17%. It is seen that several Eastern European countries such as Russia, Romania, Bulgaria, and Moldova have anomalously high upload throughput speeds. Also several countries in Western Europe such as Portugal, Belgium, France and Germany have anomalously low upload throughput speeds.
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