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The results from Ookla are mainly oriented to broadband access for the residence and the performance of the local broadband providing ISP. The measurements are made at irregular intervals as determined by the whims of the client. The clients are self selected. Ookla also measures the true throughput separately in both the up- and downstream directions. PingER on the other hand is more oriented to measurements beween academic and research sites, the measurements are made at regular intervals (every 30 minutes) and the clients are selected by the server administrators. PingER also derives the throughput from its RTT and loss measurements using the Mathis formula (TCP throughput ~ 1460*8/(RTT*sqrt(loss)) where the result is in kbits/s if the RTT is in milliseconds. Thus the measurement is an average of the up and downstream directions. Though the Mathis formula is for classic versions of TCP's (e.g. New Reno) congestion control as used in most off the shelf computers today, it assumes TCP loss (and TCP provokes loss to detect congestion) whereas PingER gets the loss from pings and thus only samples loss. For these reasons and others PingER is only a rough estimate of throughput. The relationship between RTT, loss and throughput is seen here.
Our Ookla data has about 19 million IP client addresses. It is unclear how many times a given client makes a measurement or if it uses different servers from the default. PingER has about 1900 monitoring host (server) remote host (client) pairs each measured regularly every 30 minutes, or about 3 million measurements (where a single measurement is of 10 pings) per month.
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