Device and Sensor Setup > Sensor Settings

PRTG Manual: SNMP RMON Sensor

The SNMP RMON sensor monitors traffic on a device using the Remote Monitoring (RMON) standard via the Simple Network Management Protocol (SNMP).

You can create it on an SNMP-compatible device that provides traffic data via RMON. Depending on the data that the device returns, PRTG displays traffic data for each port in different channels, which allows a detailed analysis. If available, the sensor queries 64-bit counters.

SNMP RMON Sensor

For a detailed list and descriptions of the channels that this sensor can show, see section Channel List.

Sensor in Other Languages

Dutch: SNMP RMON
French: RMON (SNMP)
German: SNMP RMON
Japanese: SNMP RMON
Portuguese: RMON (SNMP)
Russian: RMON по SNMP
Simplified Chinese: SNMP RMON
Spanish: RMON (SNMP)

Remarks

You can define the displayed sensor name with port name templates in the SNMP compatibility options of the parent device.
It might not work to query data from a probe device via SNMP (querying localhost, 127.0.0.1, or ::1). Add this device to PRTG with the IP address that it has in your network and create the SNMP sensor on this device instead.
This sensor supports the IPv6 protocol.
This sensor has a very low performance impact.
See the Knowledge Base: What value does the Transmitted channel of an RMON sensor show?
See the Knowledge Base: SNMP Traffic sensors when the device changes them
See the Knowledge Base: Where is the volume line in graphs?

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the settings that are required to create the sensor. You can change nearly all settings on the sensor's Settings tab after creation.

The settings that you select in the Add Sensor dialog are valid for all sensors that you create when you finish the dialog.

RMON Specific

Setting	Description
Ports	Select the ports that you want to monitor. PRTG creates one sensor for each port that you select. Enable check boxes in front of the respective lines to select the items. Use the check box in the table header to select all items or to cancel the selection. In large tables, use the search function in the upper-right corner. You can select interfaces and cancel the selection by clicking Select all connected interfaces, Select all disconnected interfaces, and Deselect all interfaces.

Setting

Description

Ports

Select the ports that you want to monitor. PRTG creates one sensor for each port that you select.

Enable check boxes in front of the respective lines to select the items. Use the check box in the table header to select all items or to cancel the selection. In large tables, use the search function in the upper-right corner.

You can select interfaces and cancel the selection by clicking Select all connected interfaces, Select all disconnected interfaces, and Deselect all interfaces.

Basic Sensor Settings

Click the Settings tab of a sensor to change its settings.

Basic Sensor Settings

Setting	Description
Sensor Name	Enter a name to identify the sensor.
Parent Tags	Shows tags that the sensor inherits from its parent device, parent group, and parent probe. This setting is for your information only. You cannot change it.
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. It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>). For performance reasons, it can take some minutes until you can filter for new tags that you added. The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor: snmprmon
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 () to the highest priority ().

Usually, a sensor connects to the IP Address/DNS Name of the parent device. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings.

RMON Specific

Setting	Description
Port	Shows the number of the interface port that this sensor monitors. PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.
Channel Mask	Describes which channels are available and might be useful for the Paessler support team. This setting is for your information only. You cannot change it.

Setting

Description

Port

Shows the number of the interface port that this sensor monitors.

PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Channel Mask

Describes which channels are available and might be useful for the Paessler support team.

This setting is for your information only. You cannot change it.

Sensor Display

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. You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.
Graph Type	Define how different channels are shown for this sensor: 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 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.

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.

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

Graph Type

Define how different channels are shown for this sensor:

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 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.

Inherited Settings

By default, all of these settings are inherited from objects that are higher in the hierarchy. We recommend that you 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 and to display its options.

For more information, see section Inheritance of Settings.

Scanning Interval

For more information, see section Root Group Settings, section Scanning Interval.

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.

Schedules, Dependencies, and Maintenance Window

For more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.

Access Rights

For more information, see section Root Group Settings, section Access Rights.

Channel Unit Configuration

Which channel units are available depends on the sensor type and the available parameters. If no configurable channels are available, this field shows No configurable channels.

Channel Unit Configuration

For more information, see section Root Group Settings, section Channel Unit Configuration.

Channel List

Which channels the sensor actually shows might depend on the target device, the available components, and the sensor setup.

Channel	Description
Broadcast Packets	The number of broadcast packets per second
Collisions	The number of collisions per second
CRC Errors	The number of cyclic redundancy check (CRC) errors per second
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 in percent.
Drop Events	The number of drop events per second
Fragments	The number of fragments per second
Jabbers	The number of jabbers per second
Multicast Packets	The number of multicast packets per second
Oversize Packets	The number of oversize packets per second
Packets	The number of packets per second
Packets <= 64 Byte	The number of packets with less than or equal to 64 bytes per second
Packets 65 - 127 Bytes	The number of packets with 65 - 127 bytes per second
Packets 128 - 255 Bytes	The number of packets with 128 - 255 bytes per second
Packets 256 - 511 Bytes	The number of packets with 256 - 511 bytes per second
Packets 512 - 1023 Bytes	The number of packets with 512 - 1023 bytes per second
Packets 1024 - 1518 Bytes	The number of packets with 1024 - 1518 bytes per second
Transmitted	The transmitted bytes per second This channel is the primary channel by default.
Undersize Packets	The number of undersize packets per second