Sensor of the Week: QoS (Quality of Service) Round Trip Sensor

 Originally published on September 17, 2014 by Florian Staffort
Last updated on March 03, 2022 • 7 minute read

The "Sensor of the Week" articles are a neat way for you to discover new areas of applications for PRTG Network Monitor—even ones you might yet not have thought of. This time, even if you already know and use the QoS (Quality of Service) Round Trip sensor, we urge you to keep on reading as we present to you a great new way to monitor the quality of a network connection without using remote probes: the PRTG QoS Reflector (open source) for the QoS Round Trip sensor!


You can use the QoS Round Trip sensor to measure the quality of a network connection by sending UDP (User Datagram Protocol) packets from one end of the connection to its other end. These traffic packets are then sent back to the source and the sensor measures various QoS parameters of this packet round trip in order to determine the quality of a connection. Measured values are, for example:

  • Packet loss,
  • Jitter,
  • Packet Delay Variation (PDV), and
  • Round trip time (RTT).

Due to the concept of this round trip sensor, it is mandatory to have two endpoints for QoS measurements with a reflector for the UDP packets. Until now, you had to run at least one remote probe to initiate and monitor this packet round trip, but now it's enough to place a small Python script at the end of the line—our new PRTG QoS Reflector!

Basically the PRTG QoS Reflector is a Python script that bounces all incoming UDP packets. This approach allows you to use any Linux based device that can process Python scripts at the connection end like, for example, a small Raspberry Pi which you can setup real easy. If you want to give it a try, just visit our GitHub repository and download our PRTG QoS Reflector for free!

Right now this feature is available in PRTG's Preview release channel. Please take a look at the Paessler Knowledge Base article on "QoS Round Trip Monitoring Without Remote Probes" for a detailed step-by-step guide.

If you're looking for more information on the QoS Round Trip sensor itself, please have a look at the PRTG manual instead.


All Sensors of the Week

You have missed other articles of our "Sensors of the Week" blog series? Just take a look at the last 10 sensors:

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