Tag: "speedtests"

Posted June 25, 2012 by christopher

Far too many people seem to think that when they go to Speedtest.net to test their connection, they get a number that has any bearing on reality. For most of us, it simply doesn't. This is true of other large tools for measuring connections. And it has important policy implications because the FCC contracted with a company called Sam Knows to measure wireline speeds available to Americans (I'm a volunteer in that project).

Sam Knows explains :

SamKnows has been awarded a ground breaking contract by the Federal Communications Commission (FCC) to begin a new project researching and collecting data on American fixed-line broadband speeds delivered by Internet Service Providers (ISP's) - until now, something that has never been undertaken in the USA.

The project will see SamKnows recruit a team of Broadband Community members who will, by adding a small 'White Box'’ to their home internet set up, automatically monitor their own connection speeds throughout the period of the project.

Unfortunately, SamKnows appears to be documenting fantasy, not reality.

To explain, let's start with a question Steve Gibson recently answered on his amazing netcast, Security Now (available via the TWiT network). A listener asked why he gets such large variation in repeated visits to Speedtest.net.

Security Now Logo

Steve answers the question as an engineer with a technical explanation involving the TCP/IP protocol and dropped packets. But he missed the much larger issue. Packets are dropped because the "pipes" are massively oversubscribed at various places within the network (from the wires outside you house to those closer to the central office or head end). What this means is that the cable company (and DSL company, to a lesser extent) takes 100Mbps of capacity and sells hundreds of people 20Mbps or 30 Mbps or whatever. Hence the "up to" hedge in their advertisements.

The actual capacity you have available to you depends on what your neighbors (cable) or others in the network (DSL) are doing. Dropped packets in TCP result often result from the congestion of high oversubscription ratios.

This gets us into why Speedtest.net and Sam...

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Posted September 10, 2010 by christopher

In a light cap to a light-posting week, I wanted to note a post from Fiberevolution regarding speed tests. Many of us are frustrated with the available speeds and just how they compare to what we are promised.

We have long seen a variety of criticisms of speed tests (including that operators like Comcast game the system by allowing greater speeds than one normally achieves to sites in practice), but few realized that one of the most well known tests (provided by Ookla) suffers from what appears to be a structural deficiency:

"Samples are sorted by speed, and the fastest half is averaged to eliminate anomalies and determine the result."

I wish my grades had been calculated like that back in school.

I have come around to believing we need to collect greater data about what broadband we have available in order to compare providers (naturally, I suspect we will find that community networks do a better job of offering faster speeds). M-Labs has a good start and will be essential in this endeavor.

More to come...

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