PRTG Manual: QoS (Quality of Service) Round Trip Sensor
The QoS (Quality of Service) Round Trip sensor monitors parameters regarding the quality of a network connection between two probes. This is important, for example, when using Voice over IP (VoIP) over this connection.
The sensor sends a series of User Datagram Protocol (UDP) packets from the source probe to a target at the end of the connection line. Then, the packets are sent back to the original probe ("round trip").
The sensor measures the following parameters:
- Jitter in milliseconds (maximum, minimum, average)
- Packet delay variation in milliseconds (maximum, minimum, average)
- Mean opinion score (MOS)
- Corrupted packets in percent
- Duplicated packets in percent
- Lost packets in percent
- Packets out of order in percent
- Round-trip time (RTT) in milliseconds (maximum, minimum, average)
- Time to last packet in milliseconds
- Dutch: QoS (Quality of Service) Heen en weer
- French: Aller-retour du QoS (Quality of Service)
- German: QoS (Quality of Service) Round Trip
- Japanese: ラウンドトリップ QoS(Quality of Service)
- Portuguese: Percurso de ida e volta QoS (Qualidade de serviço)
- Russian: Цикл тестирования качества обслуживания
- Simplified Chinese: QoS (服务质量) 往返
- Spanish: Ida y vuelta QoS (Calidad de servicio)
- You have to configure at least one remote probe in your PRTG on premises setup and at least two remote probes in PRTG hosted by Paessler, or you need to set up the PRTG QoS Reflector tool on the target machine at the endpoint of the monitored connection.
- This sensor has a high performance impact.
- You cannot use this sensor in cluster mode. You can only set it up on a local probe or a remote probe but not on a cluster probe.
- See the Knowledge Base: How can I monitor QoS round trips without using remote probes?
- See the Knowledge Base: How does PRTG calculate the MOS score for QoS sensors?
- See the Knowledge Base: What connection settings are necessary for the QoS (Quality of Service) Round Trip Sensor?
You cannot add this sensor to the hosted probe of a PRTG hosted by Paessler instance. If you want to use this sensor, add it to a remote probe device.
The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the setting fields that are required for creating the sensor. Therefore, you do not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.
Click the Settings tab of a sensor to change its settings.
Usually, a sensor connects to the IP Address or DNS Name of the parent device on which you created the sensor. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. See below for details on available settings.
Setting |
Description |
---|---|
Sensor Name |
Enter a meaningful name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets.
|
Parent Tags |
Shows tags that the sensor inherits from its parent device, parent group, and parent probe. This setting is shown for your information only and cannot be changed here. |
Tags |
Enter one or more tags. Confirm each tag with the Spacebar key, a comma, or the Enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case-sensitive. Tags are automatically inherited.
The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:
|
Priority |
Select a priority for the sensor. This setting determines the position of the sensor in lists. The highest priority is at the top of a list. Choose from the lowest priority ( |
Quality of Service Measurement
Setting |
Description |
---|---|
Timeout (Sec.) |
Enter a timeout in seconds for the request. If the reply takes longer than this value, the sensor cancels the request and shows a corresponding error message. Enter an integer value. The maximum value is 900 seconds (15 minutes). |
QoS Target |
Define the type of target that receives the UDP packets:
|
Target Probe |
This setting is only available if you select PRTG probe as QoS target. In the dropdown list, you see all local probes and remote probes of your setup. When running the sensor on the local probe, select a remote probe as the Target Probe. If no remote probe is available, install and connect a remote probe first or use the PRTG QoS Reflector. When running the sensor on a remote probe, select either a different remote probe or the local probe in PRTG on premises as target. The sensor measures values for the network track between the parent probe and the target probe.
|
Target Host/IP |
Define the IP address of the QoS target. If you use the QoS Reflector, enter the address of the machine on which the reflector script runs. If you use a probe, enter the address of the probe to which the parent probe connects.
|
Port |
Define the source and target port for the UDP packets. This port is used on both the source and target probe. Use a different port for each QoS sensor to make sure packets can be assigned correctly. Enter an integer value between 1024 and 65536.
|
Number of Packets |
Define how many packets the sensor sends for each scanning interval. Enter an integer value. The default value is 1000. We recommend that you use the default value. |
Size of Packets (Bytes) |
Define the size of the packets in bytes that the sensor sends. Enter an integer value. The default value is 172. We recommend that you use the default value. |
Time between Packets (ms) |
Define the time in milliseconds that the sensor waits between two packets. Enter an integer value. The default value is 20. We recommend that you use the default value. |
Setting |
Description |
---|---|
Primary Channel |
Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.
|
Graph Type |
Define how different channels are shown for this sensor:
|
Stack Unit |
This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so. |
By default, all of the following settings are inherited from objects that are higher in the hierarchy. You should change them centrally in the root group settings if necessary. To change a setting for this object only, click under the corresponding setting name to disable the inheritance. You then see the options described below.
For more information, see section Inheritance of Settings.
Click to interrupt the inheritance.
Setting |
Description |
---|---|
Scanning Interval |
Select a scanning interval from the dropdown list. The scanning interval determines the amount of time that the sensor waits between two scans. Choose from:
|
If a Sensor Query Fails |
Select the number of scanning intervals that the sensor has time to reach and to check a device again if a sensor query fails. Depending on the option that you select, the sensor can try to reach and to check a device again several times before the sensor shows the Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows the Warning status. Choose from:
|
Schedules, Dependencies, and Maintenance Window
You cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects are always active. However, you can define additional schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.
Setting |
Description |
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Schedule |
Select a schedule from the list. You can use schedules to monitor during a certain time span (days or hours) every week. Choose from:
|
Maintenance Window |
Select if you want to set up a one-time maintenance window. During a maintenance window, monitoring stops for the selected object and all child objects. They show the Paused status instead. Choose between:
|
Maintenance Begins |
This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the one-time maintenance window. |
Maintenance Ends |
This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the end date and time of the one-time maintenance window. |
Dependency Type |
Select a dependency type. You can use dependencies to pause monitoring for an object depending on the status of a different object. You can choose from:
|
Dependency |
This setting is only visible if you enable Select a sensor above. Click |
Dependency Delay (Sec.) |
This setting is only visible if you enable Select a sensor above. Define a time span in seconds for the dependency delay. After the master sensor for this dependency returns to the Up status, PRTG additionally delays the monitoring of the dependent objects by the time span you define. This can prevent false alarms, for example, after a server restart or to give systems more time for all services to start. Enter an integer value.
|
Click to interrupt the inheritance.
Setting |
Description |
---|---|
User Group Access |
Define the user groups that have access to the sensor. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights:
|
KNOWLEDGE BASE
How does PRTG calculate the MOS score for QoS sensors?
How can I monitor QoS round trips without using remote probes?
What connection settings are necessary for the QoS (Quality of Service) Round Trip Sensor?
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For more information about sensor settings, see the following sections: