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Effective bandwith

What is the effective bandwidth result on our Connection Quality Test

· Knowledgebase

Aizan's Connection Quality Test (CQT) measures effective bandwidth...

Consider this real-life example. A 10 mile stretch of road has a speed limit of 60 miles per hour. There are 5 intersections on this road with a set of traffic lights. If a vehicle travels end-to-end in 10 minutes, the vehicle has indeed traveled at 60 miles per hour. If a vehicle travels end-to-end but catches every light red, which causes the journey to take 15 minutes, then the vehicle would have traveled at a peak of 60 miles per hour but the throughput would have only been 40 miles per hour.

The TRUE performance of the first vehicle is 60 miles per hour, the TRUE performance of the second vehicle is 40 miles per hour.

Most testers do not measure throughput speed but instead attempt to measure Capacity and report the result as 'speed'. Network providers like speed testers that show highest attained because it makes dollars however a capacity test does not measure one vehicle but several vehicles at the same time, reporting the combined value over the time line.

The question to ask is therefore this, if 10 vehicles travel the 10 mile road in 10 minutes and the test reports a result of 1 vehicle per minute, does that really mean the vehicle's speed was 600mph or is it really still 60mph but there is 10 of them. Better yet, are 9 babies born in 9 months, 1 baby a month or is the experience of a mother still 1 baby in 9 months.

Which measure matters? The answer depends on who is asking the question. The service provider would argue that the 40mph vehicle did indeed travel at 60mph, therefore 60mph is the 'bandwidth'.

The driver of the vehicle would argue that while 60mph was attained it was not sustained, the throughput was only 40mph. Bandwidth is not a speed it is simply a rate, speed is really throughput with the upper limit being the bandwidth. The throughput measure is what really matters because it defines the overall user experience.

The user experience is what really matters. Imagine driving the '10 mile road' to catch a train that leaves in 12 minutes. The first vehicle in the example will catch the train with 2 minutes to spare, the second vehicle in the example will miss the train by 3 minutes. Networks are about delivering data on time… knowing you traveled at 60mph for part of the journey is of little benefit if you miss the train.

If Aizan's CQT measures throughput, why report effective bandwidth? CQT reports the effective bandwidth in conjunction with the breakdown of the bandwidth attained over the test time line; this allows the testing user to truly assess the service quality that is being provided. While many of the most popular speed testers report nice glossy numbers with cool graphics, these measures are largely of little value and wholly misleading.

Few tests if any report the consistency of speed attainment but the experience of the user is defined by this metric.

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