When discussing Internet connectivity problems the number one complaint is always about speed or the lack of it. End users relay the same message over and over again, and quite frequently users with Internet service problems are quick to defend their choice of service provider with statements like "But I have a 5 Mbps or a 10 Mbps connection so I shouldn’t have jerky video" or "But the speed tester I use says I can run 9 VoIP lines, so why are my VoIP calls often garbled?"
As speed is the prime criteria when users select an Internet service provider, when they are asked "what is the quality of the service?", the question is most often met with a puzzled along with the retort, "Quality! What do you mean by quality?"
Speed versus Quality is a crucial issue for measuring bandwidth performance. An example of speed without quality would be like driving a Ferrari during the heavily congested rush hour – while the capability of high speed exists, the speed is not realized due to other factors. We all drive on highways and through experience we know only too well that our journey time will not be governed by the maximum speed of our car or the maximum speed of the highway. In reality it will be governed by the many different events that occur on our journey such as weather, congestion, accident backup or highway construction.
Running a speed test that shows a slow throughput without consideration of the event information to help the ISP to identify and resolve inherent performance issues has absolutely no value. Only through careful measurement of every aspect of the end_to_end journey can a speed test really start to benefit the user, and more importantly benefit the service provider by providing the information needed to identify the problem.
In the Internet world there are many different issues that affect how our applications perform. When performance is as we expect we are content, when it is not we get frustrated. Understanding the events that impact your Internet connection along with the quality of service delivered for your applications is vitally important for the problems to be resolved. In our highway example, if the quality of the highway service was to be measured by its users, it would be a measure of the highway’s ability to deliver you to your destination in a time that closely matches the time it would take if you were able to sustain the maximum allowed speed. In other words, assuming you are driving as fast as allowed by the legal limit, the calculation of highway quality would be:
Highway Quality % = Your Speed x 100/maximum allowed highway speed
If the highway is legally limited to 65 mph and your average speed is 35 mph then the quality is:
Highway Quality % = 35/65 x 100 = 53%
The quality measure is critical because if the highway quality is such that you are only able to maintain 30 mph when the application (arriving at the airport to catch the flight) requires 35 mph, you will certainly miss your flight.
I know how to measure speed, how do I measure the quality?
The key to success of an Internet connection is a combination of a good speed with a good quality of service. In fact, it is preferable to have a slower 3 Mbps (Megabits per second) connection with a 99% quality of service rather than a 6 Mbps connection with a 50% quality of service. Both will achieve about the same throughput overall, however the delays inherent in the packet flow that result in the lower of quality of service will adversely impact time_dependant applications such as VoIP, video or MP3.
In order to measure quality, an Internet connection testing application has to measure the events for the Internet connection as well as the speed. Otherwise, you only know that the traffic is slow but you have no clue as to the cause. To better ascertain the cause requires that the testing application is capable of measuring the traffic flow as well as the traffic speed. Graphical views of the traffic flow show the inherent delays occurring with the data along with the all important timing.
Once the delay picture is exposed, you can start to see the impact the delays have on the data movement and thusly on the applications. For example, in line with our analogy of driving to the airport, you will be able to see those parts of the data packet journey that are fast and those parts that are not. You will also be able to see if the fast data movement periods are reaching the contracted maximum or whether, as is often the case, the fast periods are still not meeting the contracted service levels. In addition, the volume of delays, size of the delays and the timing of the delays provide the insight to understand whether the problem is traffic related (i.e. Internet congestion), or whether it is police related, i.e. some other sort of data traffic management or time multiplexing is being imposed by the ISP. The chart below shows a good example of speed versus quality.
