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What is Bandwidth?
In computer networking, bandwidth refers to the measurement of data that is transferred between two points within a set amount of time. Typically expressed in bits, megabits, or gigabits per second, bandwidth is shared among devices connected to the same network; this means activities like streaming video content or downloading large files can use a large amount of bandwidth and slow down connections for other devices on the network.
Bandwidth can also pertain to some data-transferring devices themselves, as in the case of I/O devices. For example, a fast disk drive can be hampered by a bus with a low bandwidth. This is the main reason why buses like AGP were developed for the PC.
In telecommunications, bandwidth refers to the range that carries a signal within a band of frequencies. This type of bandwidth is measured in Hertz (Hz) and is calculated by finding the difference between the upper and lower frequency limits of a signal. It is important to note that different types of signals (music, voice, picture, etc.) require different bandwidths.
Bandwidth vs. Speed
Although bandwidth and speed (or latency) are closely related and often used interchangeably, there are some key differences to highlight between the two concepts:
- Bandwidth describes the volume of data that can be transferred at a given time.
- Speed describes the length of time it takes for data to be transferred.
To use an analogy, think of an interstate highway. The number of cars that are able to pass from one mile marker to the next within a set timeframe would be considered the highway’s bandwidth, whereas the speed would be the rate of time it takes for one car to travel between mile markers. Factors that impact bandwidth include the size of the road (or the size of the cable) and the number of cars trying to travel at once (or the number of connections in use at the same time). Bandwidth can certainly impact speed (the more cars there are on the road, the longer it takes for all of them to get from place to place), but connection speeds can also be slowed by how far data needs to travel and other environmental factors. Together, bandwidth and speed create a network’s throughput.
There are two primary types of bandwidth: symmetric and asymmetric. Symmetrical bandwidth connections, as the name suggests, exist when an equal amount of data is transmitted at an equal amount of speed between two points. Video conferencing is an example of a symmetrical bandwidth connection.
On the other hand, asymmetrical bandwidth connections are characterized by differences in the upload and download speeds. These types of connections are typically more cost-effective than symmetrical bandwidth and offer faster speeds for downloading than uploading. Broadband and DSL internet connections are examples of asymmetrical bandwidth connections.
Bandwidth and throughput are closely related but have distinct characteristics. Throughput is a measurement of how much data is transmitted from one point to another within a set amount of time. Bandwidth is a measurement of the amount of data that can be transmitted simultaneously.
To use another analogy, throughput is like the amount of water you can fill in a bucket within a certain amount of time, and bandwidth is like the size of the pipes through which the water is flowing. Wider pipes allow for better water flow, just as more bandwidth allows for more data to be transmitted at once.
Internet bandwidth can be measured through speed tests. These tests send data packets from one point to another and measure the length of time they take to be delivered. One of the biggest factors that can impact bandwidth is network congestion. For this reason, some internet service providers engage in the practice of bandwidth throttling to intentionally manipulate the bandwidth consumption.