Understanding DSL Speeds

dsl speedBroadband performance is often measured in very simple terms, but those terms can be just as misleading as they are impressive.  In fact, broadband providers count on the complexity of modern wide array networking and broadband technologies to create circumstances where they can promise the world and deliver less while charging a reasonable price.  The only way to get full value for what you shop for, especially when it comes to DSL speeds, is to understand DSL speeds.  Here are 6 simple rules to understanding DSL speeds.

Understanding DSL Speeds Part 1: Downstream Speeds

Easily the single most common number that DSL providers and other broadband companies like to tout is their downstream speed.  Simply put, downstream is how much data you can download from the Internet every second.  The bigger the number, the faster the connection seems, but there is a limitation on this in the form of what is generically referred to as error checking.  Networks need to send back summaries of data received rather frequently so that the sender knows that the data was sent in good order.  If the downstream far outstrips the ability to send data (which will be discussed in the next bullet point) then the numbers become meaningless as the error checking data may be delayed.

Understanding DSL Speeds Part 2: Upstream Speeds

Upstream speeds are how fast data is transmitted from your device or network out to the Internet in any given period of time.  Again, the faster the speed the better.  There are many that have seen the value of symmetry, or the downstream and upstream being equal, in that the error checking data that goes back out fast makes the network seem that much faster.

Understanding DSL Speeds Part 3: Up To Performance

For some reason the entire concept of ‘up to’ performance numbers have suddenly taken over the world of broadband advertising, and this includes DSL speeds.  Up to speeds are not guaranteed and may never be reached, or may be available only in bursts, and/or during certain time frames.  The concept is simple: you get a minimum speed guaranteed to you, and if the network is not burdened with too much traffic then you get more bandwidth if you are using it.

Understanding DSL Speeds Part 4: Latency

Latency is the description of how fast data can go from your device to a point on the Internet and return.  This round trip is a good measure of how ‘snappy’ or responsive a connection seems.  One of DSL’s strengths is that it has a low latency compared to comparably-priced broadband offerings.

Understanding DSL Speeds Part 5: Reliability

Reliability is king, as there is no point in having a fast connection if the connection is offline all the time.  For reliability in DSL you want to have a connection with a high signal to noise ratio and a low attenuation measured over a great distance.  It also helps if the DSL network is not overburdened and considered to be highly reliable by users, so do your homework before you buy.

Understanding DSL Speeds Part 6: Testing

There are plenty of tools out there to test broadband performance, and they can serve as decent measuring sticks for your own DSL.  Some of these tests are done via websites that load images and other content as fast as possible in a timed test, but these tests tend to take forever when there is some sort of technical problem.  There are other tests that are built into applications and games that may use real software, i.e. programs you want to use instead of just theoretical benchmarks, to determine how fast or suitable an Internet connection is for what you are looking to do.  A good mix of both should show you the full picture, but there are some considerations.

The first consideration is that you want to be sure that you are not connecting wirelessly unless you have no other choice as wireless signals have inherent reliability issues that may skew test results.  You may also want to shut down other non-essential programs to ensure that you get the most repeatable results.  If you are doing real-world tests, these are the same items that you want to shut down during real-world usage if at all possible.