PRTG Manual: sFlow Sensor
The sFlow sensor receives traffic data from a sFlow V5 compatible device and shows the traffic by type. Only header traffic will be analyzed. Please make sure the device matches the sFlow version V5! There are several filter options available to divide traffic into different channels.
Note: In order for the sensor to work, sFlow V5 export must be enabled on the device. The device must send the flow data stream to the IP address of the PRTG probe system on which the sensor is set up (either a local or remote probe).
The sensor accepts RAW data only. The stream must be sent via IPv4. This sensor type cannot be used in cluster mode. You can set it up on a local probe or remote probe only, not on a cluster probe.
For a general introduction to the technology behind flow monitoring, please see Monitoring Bandwidth via Flows section.
Limitations of This Sensor Type
There are some limitations that you want to consider before using this sensor type:
- Only sFlow version 5 datagrams are supported
- Only IPv4 flows are supported
- Only the "raw packet header" format is supported
- Only the "Flow sample" format is supported. "Extended flow" and "Counter" formats cannot be processed
- PRTG processes only samples where the source ID matches the ifIndex of the input interface (avoiding double counted traffic) and ascending sequence numbers. Due to internal limitations, only interface numbers up to 65535 are supported.
- Sample packets have to be of ethernet type "IP" (with optional VLAN tag)
- Sampled packets of type TCP and UDP are supported
We recommend using sFlow tester for debugging (see More section below).
The Add Sensor dialog appears when adding a new sensor on a device manually. It only shows the setting fields that are imperative for creating the sensor. Therefore, you will not see all setting fields in this dialog. You can change all settings in the sensor's Settings tab later.
On the sensor's details page, click on the Settings tab to change settings.
Note: If not set explicitly in a sensor's settings, it will connect to the IP Address or DNS Name defined in the settings of the parent device the sensor is created on.
Basic Sensor Settings |
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Sensor Name |
Enter a meaningful name to identify the sensor. The name will be shown by default in the device tree and in all alarms. |
Tags |
Enter one or more tags, separated by space or comma. You can use tags to group sensors and use tag-filtered views later on. Tags are not case sensitive. We recommend using the default value. You can add additional tags to it, if you like. Other tags are automatically inherited from objects further up in the device tree. Those are not visible here. |
Priority |
Select a priority for the sensor. This setting determines where the sensor will be placed in sensor lists. Top priority will be at the top of a list. You can choose from one star (low priority) to five stars (top priority). |
sFlow Specific Settings |
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Receive sFlow Packets on UDP Port |
Enter the UDP port number on which the flow packets are received. It must match the one you have configured in the sFlow export options of your hardware router device. Default value is 6343. Please enter an integer value. Note: When configuring export, please make sure you select the appropriate sFlow version 5. |
Sender IP |
Enter the IP address of the sending device you want to receive the sFlow from. Enter an IP address to receive data from a specific device only, or leave the field empty to receive data from any device on the specified port. |
Receive sFlow Packets on IP |
Select the IP address(es) on which PRTG listens to sFlow packets. The list of IP addresses shown here is specific to your setup. To select an IP address, add a check mark in front of the respective line. The IP address selected here must match the one configured in the sFlow export options of your hardware router device. Note: When configuring export, please make sure you select the appropriate sFlow version 5. |
Channel Configuration |
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Channel Selection |
Define the categories the traffic will be accounted to. There are different groups of traffic available. Choose between:
For each traffic group, you can select how many channels will be used for each group, i.e. how detailed traffic will be divided. For each group, choose between:
Note: You can change the default configuration for groups and channels. For details, please see section More. |
Filtering |
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Include Filter |
Define if you want to filter any traffic. If you leave this field empty, all traffic will be included. To include specific traffic only, define filters using a special syntax. For detailed information, please see Filter Rules for xFlow, IPFIX, and Packet Sniffer Sensors section. |
Exclude Filter |
First, the filters defined in the Include Filter field are considered. From this subset, you can explicitly exclude traffic, using the same syntax. For detailed information, please see Filter Rules for xFlow, IPFIX, and Packet Sniffer Sensors section. |
Sensor Display |
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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 will always be displayed underneath the sensor's name. The available options depend on what channels are available for this sensor. Note: You can set another primary channel later by clicking on the pin symbol of a channel in the sensor's overview tab. |
Chart Type |
Define how different channels will be shown for this sensor.
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Stack Unit |
This setting is only available if stacked graphs are selected above. Choose a unit from the list. All channels with this unit will be 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. |
Primary Toplist |
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Primary Toplist |
Define which will be your primary toplist. It will be shown in maps when adding a toplist object. Choose from:
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By default, all following settings are inherited from objects higher in the hierarchy and should be changed there, if necessary. Often, best practice is to change them centrally in the Root group's settings. To change a setting for this object, disable inheritance by clicking on the check mark symbol in front of the respective setting name. You will then see the options described below.
Scanning Interval |
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Scanning Interval |
The scanning interval determines the time the sensor waits between two scans. Select a scanning interval (seconds, minutes, or hours) from the list. You can change the available intervals in the system administration. |
Schedules, Dependencies, and Maintenance Window |
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Note: Inheritance for schedules, dependencies, and maintenance windows cannot be interrupted; the according settings from the parent objects will always be active. However, you can define additional settings here. They will be active in parallel to the parent objects' settings. |
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Schedule |
Select a schedule from the list. Schedules can be used to monitor for a certain time span (days, hours) throughout the week. With the period list option it is also possible to pause monitoring for a specific time span. You can create new schedules and edit existing ones in the account settings. Note: Schedules are generally inherited. New schedules will be added to existing ones, so all schedules are active. |
Maintenance Window |
Specify if you want to set-up a one-time maintenance window. During a maintenance window this object and all child objects will not be monitored. They will enter a paused state then. Choose between:
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Maintenance Begins At |
This field is only visible if maintenance window is enabled above. Use the date time picker to enter the start date and time of the maintenance window. |
Maintenance End At |
This field is only visible if maintenance window is enabled above. Use the date time picker to enter the end date and time of the maintenance window. |
Dependency Type |
Define a dependency type. Dependencies can be used to pause monitoring for an object depending on the status of another. You can choose between:
Note: Testing your dependencies is easy! Simply choose Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later all dependent objects should be paused. |
Dependency |
This field is only visible if the select object option is enabled above. Click on the reading-glass symbol and use the object selector to choose an object on which the current sensor will be dependent on. |
Delay (Seconds) |
Define a time span. After the master object for this dependency comes back to an Up status, monitoring of the depending objects will be additionally delayed by the defined time span. This can help avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Please enter an integer value in seconds. Note: This setting is not available if you choose this sensor to be the Master object for parent. In this case, please define delays in the parent Device Settings or the superior Group Settings. |
Access Rights |
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User Group Access |
Define which user group(s) will have access to the object you're editing. A table with user groups and right is shown; it contains all user groups from your setup. For each user group you can choose from the following access rights:
You can create new user groups in the System Administration—User Groups settings. To automatically set all objects further down in the hierarchy to inherit this object's access rights, set a check mark for the Revert children's access rights to inherited option. For more details about access rights, please see section User Access Rights. |
Channel Unit Configuration |
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Channel Unit Types |
For each type of sensor channel, define the unit in which data is displayed. If defined on probe, group, or device level, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available):
Note: Custom channel types can be set on sensor level only. |
For all flow and packet sniffer sensors there are Toplists available on the Overview tab of a sensor's detail page. Using toplists, you can review traffic data of small time periods in great detail. For more information, please see Toplists section.
Paessler Website: Paessler sFlow Tester
Knowledge Base: How can I change the default groups and channels for xFlow and Packet Sniffer sensors?
In order to change display settings, spike filter, and limits, please switch to the sensor's Overview tab and click on the gear icon of a specific channel. For detailed information, please see Sensor Channels Settings section.
Click on the Notifications tab to change notification triggers. For detailed information, please see Sensor Notifications Settings section.
For more general information about settings, please see Object Settings section.
For information about sensor settings, please see the following sections:
- Sensor Settings
- List of Available Sensor Types
- Additional Sensor Types (Custom Sensors)
- Sensor Channels Settings
- Sensor Notifications Settings
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