By Ciaran Gillespie, Solutions Engineer
What is Bandwidth?
Before jumping into the differences between symmetric and asymmetric bandwidth let’s go back to the basics and review the question - what is bandwidth?
Simply put, in networking, bandwidth is a measure of how much data can be transmitted down a particular medium, for example, copper, fiber, and wireless links in a given amount of time, usually measured in seconds. The standard unit for measuring network communications is Bits per second (Bps) or Kbps (Kilobits per second) and Mbps (Megabits per second).
One common misconception to note is bandwidth is not a measure of network speed, but rather the maximum transmission of a link. The measure of network speed is how much data can be transmitted to its destination. This can vary depending on the equipment, time of day, network load, and other conditions.
What is Asymmetric and Symmetric Bandwidth?
In the ISP (Internet Service Provider) world, when purchasing broadband, the advertised bandwidth is usually focusing on the download speed. If you run a test on speedtest.net from a residential or small business connection you may notice the download figure is significantly more than the upload, this is known as an asymmetric connection.
The primary reason behind this is that download traffic is typically more important for customers who don’t have a need for on-prem servers and services to upload large amounts of data to other devices across the internet. Average residential and small business customers will simply consume more download traffic, so ISPs have designed their networks to favor download bandwidth.
On the technical side, asymmetric connections can also have limitations due to the cables used (for example, ADSL and later VDSL are protocols used to transmit data over phone lines, these were designed to favor traffic on the download side). One benefit to an Asymmetrical connection is that they are usually cheaper, and easier to provision.
Here is a screenshot showing the WAN usage of a typical household over a 24-hour period. Note traffic is consumed more in inbound (download):
For larger businesses and enterprise customers, it is typical for them to purchase a symmetrical broadband connection. In a symmetric connection the upload is equal to the download, so an enterprise customer may purchase a 100/100 connection, which gives 100 Mbps in both directions.
These connections usually come in the form of leased lines, where the cable/fiber is dedicated to the customer from their premises back to the telephone exchange or ISP point of presence. This means the ISP can guarantee the bandwidth that is provided to the end customer.
The main reason to choose a symmetric connection is that there is a requirement to run on-prem services such as web applications, VoIP systems, or VPNs where remote devices are going to be consuming your bandwidth in the upload direction. Another reason is when you need to upload large amounts of data such as documents and HD video or run many simultaneous video conferencing applications.
Which connection is right for me?
Choosing the right type of connection comes down to business requirements. If running a small business with only a handful of users, a cheaper asymmetrical connection may be right for you. If running a medium to large site with reliance on on-prem services, cloud applications, and video conferencing, then you may want to consider a symmetrical connection. Although business-grade contracts come with stringent SLAs regarding uptime and line quality, we always recommend implementing redundancy (either via another line or 4G/5G).
Frequently Asked Questions
What is the difference between symmetric and asymmetric bandwidth?
Symmetric bandwidth means your internet connection has equal upload and download speeds. Asymmetric bandwidth means your download speed is faster than your upload speed, which is more common for residential internet plans. Symmetric connections are better for running on-premise services that require high upload speeds.
Why do most home internet plans use asymmetric bandwidth?
Asymmetric bandwidth is cheaper for internet providers to offer and meets the needs of most home users, who consume more download bandwidth for streaming, surfing the web, etc. Home users don’t typically need fast upload speeds.
When should I choose a symmetric bandwidth connection?
Symmetric connections are best for businesses running on-premise services like web apps, VoIP, or VPNs that require high upload speeds. They allow for reliable video conferencing and uploading large files. Symmetric connections provide equal performance in both directions.
What kind of businesses need symmetric bandwidth?
Any business that frequently uploads data like videos, medical imagery, backups, or large documents will benefit from symmetric connections.
Does more bandwidth mean faster speeds?
Not necessarily. Bandwidth refers to the maximum capacity, while speed refers to actual throughput. You may have a high-bandwidth connection that has slow speeds due to network congestion or equipment limitations. Speed depends on several factors. Read our article here to learn how much bandwidth you should expect your security cameras to use.
What factors affect my actual internet speeds?
Actual speeds depend on networking equipment, the number of concurrent users/devices, time of day, applications used, and network conditions. More users or congestion slows speeds. WiFi also limits speeds compared to a wired ethernet connection.