Bandwidth Monitoring 
with PRTG

Bandwidth refers to the maximum rate at which data can be transmitted over a network or communication channel in a given amount of time. It's typically measured in bits per second (bps), such as megabits per second (Mbps) or gigabits per second (Gbps).

In networking, bandwidth describes the capacity of a network connection. A higher bandwidth means that more data can flow through the connection simultaneously, enabling faster data transfer. For example, if a home internet connection has a bandwidth of 100 Mbps, it can transfer up to 100 million bits per second.

Bandwidth monitoring is a method to measure the actual bandwidth that is available on a local system (LAN or WiFi). Bandwidth monitoring tools display real-time data such as download and upload speed, or latency and thus help prevent network strain and aid in troubleshooting.

Private individuals and professionals alike use bandwidth monitoring with PRTG to check for available bandwidth.

In professional business settings, it has severe consequences if only limited bandwidth is available. Disruptions lead to idleness on the part of employees and customers – and a corresponding loss of sales and revenue. This is why administrators must be able to immediately determine and eliminate bandwidth hogs.

PRTG solves bandwidth issues by helping you to...

• Easily detect & measure heavy bandwidth overloads
• Quickly recognize potential disruptions
• Clearly see which user, service, or device is using the most bandwidth

Would you like to know if your Internet service provider actually provides the bandwidth they've promised? Like many administrators, you probably perform many SLA checks – but how do you test your bandwidth?

There are two primary challenges of testing bandwidth:

• Paralyzing your network: To test the maximum throughput, you must use your line to maximum capacity. This means that there will be no more resources for other data during the network test. In other words, you'll paralyze your network.
• Isolating the test track: For a 100% measurement, you'll essentially need two computers which are directly located on the ends of the line whose bandwidth you want to test. Otherwise, you will simultaneously test all network devices found on the "test track".

For these reasons, you cannot measure the bandwidth directly during the entire test, but must test the speed of the connection by generating short load peaks. You can do this, for example, by downloading a small file (a few KB) every few minutes and measuring the time it takes for the download to finish.

Create three HTTP Advanced sensors that access several files of about 500 KB each from various "fast servers" (for example, the static websites of your Internet service provider).

Let the sensors run for a few hours with a 5-minute scanning interval. The sensors have a channel that specifies the bandwidth achieved during the file download in Kbps.

If you have a data line with a specified bandwidth of 4 Mbps, for example, the network test of downloading a 500 KB file should last 1 second: 4 Megabits per second = 0.5 MB per second = 500 KB per second

If your line is used by others during the network test, you will see jitter (unwanted fluctuations) on the curve because your test did not always run with the full amount of available bandwidth. If during the test there was no other traffic on the line, your curve should closely resemble a straight line.

Bandwidth checks with PRTG will allow you to monitor your network closely and detect potential bottlenecks before they can cause real harm.

In PRTG, “sensors” are the basic monitoring elements. One sensor usually monitors one measured value in your network, for example the traffic of a switch port, the CPU load of a server, or the free space on a disk drive. On average, you need about 5-10 sensors per device or one sensor per switch port.