I visited a Verizon Wireless store recently. While my girlfriend worked with tech support to repair an issue with her phone, I spoke with a Verizon salesperson who tried to sell me Verizon FIOS internet service. I told the salesperson that I would switch from Comcast, my current provider, if and only if Verizon offered me a better price. I detailed the services that I required and the salesperson quoted me a price that was slightly higher than the price I paid to Comcast. I declined to sign up for the service.
The salesperson asked me to consider switching anyway and claimed that Verizon’s internet service was significantly faster than my internet service with Comcast. I replied that I was unlikely to notice any significant difference in performance, which the salesperson disputed.
The salesperson’s claim was based solely on the bandwidth of the connections in question. The Verizon package being marketed to me included internet service with a stated bandwidth of 20 Mbps downstream and 5 Mbps upstream. The internet service I have with Comcast claims a bandwidth of 6 Mbps downstream and 1.5 Mbps upstream. The salesperson did not consider that latency is a measure of connection quality that is at least as important to me as bandwidth.
What is latency (with respect to an internet connection)?
Latency is the amount of time between when you start sending data and when the recipient starts receiving it. Latency is often measured in milliseconds. When you visit a web site, your computer sends a request to the web server that hosts the site. The web server responds with a web page. Latency, not bandwidth, determines how quickly your request gets to the web server and how quickly you start to see the web page.
What is bandwidth?
Bandwidth is the amount of data that can be transmitted per unit of time. Bandwidth is often measured in megabits per second. While the request that your computer sends to a web server is very small, the actually web page that the web server sends back is much larger. Bandwidth determines how long it will take for the entire web page to appear.
Which is more important when determining the speed of an internet connection?
Both measurements are important. When browsing typical web sites, checking email, and playing online games, low latency is far more important than high bandwidth. When downloading music or sending emails with large attachments, high bandwidth is more important.
I declined to pay extra for Verizon’s service, which does offer significantly higher bandwidth, because it is unlikely to improve my experience. I primarily use applications that require low latency, not high bandwidth. The extra bandwidth offered by Verizon isn’t necessary to me. Even if Verizon’s connection offers lower latency (which I believe it does), I’m unwilling to pay more for it. The latency of my Comcast connection is excellent.
Examples of latency and bandwidth
Consider a situation in which you bring your collection of 500 DVDs to your friend’s house, which is 5 minutes from yours. You’ve just transferred 18,800,000 Mb in 300 s for a bandwidth of 62,667 Mbps. Since the first piece of data arrived 5 minutes after you started, your latency is 300 s. This “connection” has a very high bandwidth but also a very high latency.
You could have sent the data on the DVDs to your friend electronically. Consider a situation in which you upload the data over your 5 Mbps FIOS connection. Perhaps it takes 50 ms for your friend to start receiving the data, so your latency is 50 ms. Unfortunately, the bandwidth is only 5 Mbps, so it takes you 44 days to transfer all of the data.
In this situation you had a very large amount of data to transfer, so very high bandwidth was important.
Consider playing a real time action game online against your friend. Each time you move, jump, or shoot, you need your friend to see it as quickly as possible. You don’t need to transmit much information, you just need to transmit it quickly. In this case, low latency is far more important than high bandwidth.
I’m not making any claim that Comcast is better than Verizon. In your situation, Verizon’s services may be appropriate and may be cheaper than Comcast’s. My goal with this post is to demonstrate that bandwidth alone is not representative of the usefulness of an internet connection.