What Exactly is Bandwidth?

By: Daniel Imbellino
Updated: Feb 28, 2013

I can’t count how many times I was on XBOX Live and heard people bragging about their internet connections bandwidth. It’s too bad none of them really understood what bandwidth was, or how their ISP’s determine their available bandwidth. Here I’m going to try and clear up some of the misinformation that seems to be lurking around regarding what bandwidth is, and how it works.

Bandwidth is simply the amount of data that can be transmitted across or through a given network at one time, this is also known as a “Theoretical Maximum Data Rate.” Bandwidth within networks is generally rated in Mb/s (Megabits Per Second), NOT MB/s (MegaBytes Per Second). This is one of the biggest misconceptions I’ve seen. Too many believe that data transmission over a network is measured in Bytes and not bits. First off, what is a “bit” or a “Byte”. Notice I capitalized The B in Byte, but not bit. 1 bit is the equivalent of the smallest piece of data that can be processed within a computer or piece of networking equipment logically. Most computer systems today process data in Bytes. One Byte is the equivalent of 8 bits. Most operating systems such as those in the Windows family process data 32 or 64 bits at a time. Notice that both 32 and 64 are multiples of 8, or 32bits = 4Bytes, and 64bits = 8Bytes respectively.

Data transmissions in networks are always measured in bits, since network interface devices are known to break down bytes from say a data file for instance, into bits for transmission across a network. You might also come across the term “thruput” in network bandwidth measurements.

With your home internet service, there are two main measurements of bandwidth that you should be aware of. These are known as an “up-link” and a “down-link.” The down-link is a measurement of how much data comes into your network from outside networks, while the up-link is a measurement of how much data is transferred out from your network. ISP’s assume that the average home internet user is going to request more data than they will typically transmit back out onto the internet. For this reason, ISP’s tend to provide more available bandwidth to home user’s down-links, vs. their up-uplinks. Think about it? Most of what an individual does on the internet is request information. Checking your email, watching a video on Youtube, or checking the local weather online all require data to be transmitted on the down-link to users. If your ISP says your bandwidth is 30Mb/s, they are referring to your down-link (the data that is transmitted to your network from the internet). But the typical up-link bandwidth for home internet users in the U.S is only about 1Mb/s today. Many ISP’s are now offering higher bandwidths for up-links nowadays. If you play on XBOX Live, you will need good bandwidth measurements on both your up-link and down-link bandwidth’s, otherwise you will have a pretty lag experience at best. Playing games online with XBOX requires your console to transmit data to a server on the internet, while simultaneously receiving data from that server in return. To get the best optimal network bandwidth for your online gaming, be sure to measure your current available bandwidth. You can do this by visiting SpeedTest.Net. Speed Test is free to use, and has very good accuracy when measuring bandwidths. It will give you a quick benchmark on both your up-link and down-link, effectively showing you what your maximum thru-put is on both.

Here is an example of results obtained using my home network for testing from SpeedTest.Net:

internet speed test results

Looks like I scored pretty good, but take a look at charters only 3 out of 5 stars as indicated by Speedtest. Charter has made strides to implement St Louis Metro wide Fiber Optic internet services that provide bandwidths up to 1Gb/s for those who need or can afford it. Implementing new technologies sometimes comes with hurdles unfortunately. In the case of Charter Communications, the company experienced major problems during the shift to Fiber networking. At one point my internet was down for almost a month! For obvious reasons this angered many Charter subscribers. Just be aware, it takes extensive testing to implement new networking technologies, patience is key. Fiber Optic data transmission is the fastest and most reliable of all current forms of physical networking today. For one, Fiber Optics are immune to EMI (Electro Magnetic Interference), RFI (Radio Frequency Interference), and its transmissions travel at the speed of light! Depending on where you live, you may have several choices of internet services to choose from, just make sure to ask questions, and find out as much information about the service you are interested in before making the purchase.

Bandwidth is also used by IPS’s and web hosts to determine a maximum allowed monthly bandwidth allowance. Most mobile 4G internet services have a bandwidth cap somewhere, unless you pay for premium services.

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