PRTG Manual: QoS (Quality of Service) Round Trip Sensor

Performance impact

This sensor has a high performance impact. We recommend that you use no more than 200 of this sensor on each probe.

Remote probe

This sensor requires that you configure at least one classic remote probe in your PRTG Network Monitor setup and at least two classic remote probes in PRTG Hosted Monitor, or you must set up the PRTG QoS Reflector tool on the target system at the endpoint of the connection that you want to monitor.

Cluster probe

This sensor does not support cluster probes. You can only set it up on local probes or remote probes.

IPv4

This sensor only supports IPv4.

Knowledge Base

• Knowledge Base: How can I monitor QoS round trips without using remote probes?
• Knowledge Base: How does PRTG calculate the MOS score for QoS sensors?
• Knowledge Base: What connection settings are necessary for the QoS (Quality of Service) Round Trip sensor?

Hosted probe

You cannot add this sensor to the hosted probe of a PRTG Hosted Monitor instance. If you want to use this sensor, add it to a remote probe device.

Timeout (Sec.)

Enter a timeout in seconds for the request. Enter an integer. The maximum timeout value is 900 seconds (15 minutes).

If the reply takes longer than this value, the sensor cancels the request and shows a corresponding error message.

QoS Target

Define the type of target that receives the UDP packets:

• Probe (default): Use a probe as the connection endpoint.
• Custom target: Use the PRTG QoS Reflector as the connection endpoint.

For more information about the QoS Reflector, see the Knowledge Base: How can I monitor QoS round trips without using remote probes?

Target Probe

This setting is only visible if you select Probe (default) above.

Define the target probe that receives the UDP packets. The dropdown list shows all local probes and remote probes in your setup.

If you want to run 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. Alternatively, you can use the PRTG QoS Reflector.

If you want to run the sensor on a remote probe, select either a different remote probe or the local probe as the target. The sensor measures values for the network track between the parent probe and the target probe.

You must make sure that firewalls or network address translation (NAT) rules allow UDP packets to reach the target probe. The probe automatically opens the Windows firewall on the target system. For more information, see the Knowledge Base: What connection settings are necessary for the QoS (Quality of Service) Round Trip sensor?

In PRTG Hosted Monitor, you can only select a different remote probe as the target probe. QoS measurements for connections to the hosted probe are not possible.

Target Host/IP Address

Define the IP address of the QoS target:

• If you use the QoS Reflector, enter the address of the system on which the reflector script runs.
• If you use a probe, enter the address of the probe to which the source probe connects.

Port

Define the source and target port for the UDP packets. Both the source probe and the target probe use this port. Enter an integer. The default port is 50000. PRTG supports the port numbers 1024-65536 for UDP packets.

Use a different port for each QoS (Quality of Service) Round Trip sensor to make sure that PRTG can assign packets correctly.

The port must be available on both the source system and the target system.

Number of Packets

Define the number of packets that the sensor sends with each scanning interval. Enter an integer. The default value is 1000. The minimum value is 10. The maximum value is 1000.

We recommend that you use the default value.

Packet Size (Bytes)

Define the size of the packets in bytes that the sensor sends. Enter an integer. The default value is 172. The minimum value is 172. The maximum value is 4500.

We recommend that you use the default value.

Packet Delay (ms)

Define the time in milliseconds (ms) that the sensor waits between two packets. Enter an integer. The default value is 20. The minimum value is 10. The maximum value is 1000.

We recommend that you use the default value.

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, PRTG displays the last value of the primary channel below the sensor's name. The available options depend on what channels are available for this sensor.

You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.

Graph Type

Define how this sensor shows different channels:

• Show channels independently (default): Show a graph for each channel.
• Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.
  You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you select Stack channels on top of each other above.

Select a unit from the list. PRTG stacks all channels with this unit 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.

Downtime

In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status

Jitter Average

The average jitter

Jitter Max

The maximum jitter

This channel is the primary channel by default.

Jitter Min

The minimum jitter

MOS

The MOS

Packet Delay Variation Average

The average packet delay variation

Packet Delay Variation Max

The maximum packet delay variation

Packet Delay Variation Min

The minimum packet delay variation

This channel has a default limit:

• Upper warning limit: 100

Packets Corrupted

The corrupted packets (%)

This channel has a default limit:

• Upper warning limit: 0

Packets Duplicated

The duplicated packets (%)

This channel has a default limit:

• Upper warning limit: 0

Packets Lost

The lost packets (%)

This channel has a default limit:

• Upper warning limit: 1

Packets Out Of Order

The out of order packets (%)

This channel has a default limit:

• Upper warning limit: 0

RTT (Average)

The average RTT

RTT (Maximum)

The maximum RTT

RTT (Minimum)

The minimum RTT