Devices disappear or incorrect after being discovered (merging into another device)

When discovering a new device, the device appears to have vanished or merged with another existing device at the end of the discovery process. This can occur when using the New Scan option in Discovery (discovered devices) or when using the New Device option under My Network (monitored devices).

Apr 16, 2020
Knowledge

Title

URL Name

Devices-disappear-after-a-discovery-update-or-get-merged-into-a-different-device

Article Number

000190591

Environment

Question/Problem Description

After running a Discovery scan, no Devices are added to the Discovered Network. The devices can be pinged from the WUG app server. Manually adding a device also results in no new devices being created.

Experiencing an issue adding new nodes / devices into WUG for monitoring

Tried manually adding the server and it detects it but lists current status deleted on the scan history. I would like to get it added to the list but it is not doing so

Unable to add device to be monitored

Steps to Reproduce

Clarifying Information

The resolution steps will use the following example for screenshots and details:

When discovering a new device, the device appears to have vanished or merged with another existing device at the end of the discovery process. This can occur when using the New Scan option in Discovery (discovered devices) or when using the New Device option under My Network (monitored devices).
For Example, here is a New Scan for a device with IP address 10.248.7.26. The assumption is that this is a new device.
A screenshot of a computer Description automatically generated

During the scan, it appears to be found correctly:
A screenshot of a computer Description automatically generated

After the scan is complete, when reviewing the Scan History (Discover / Scan History), the report shows one device was discovered (as expected), and when clicking on the “1” the scan history results in the scan details, as in this image:

As expected, the IP address scanned is displayed. What is odd is that the Scan Result says “Monitored”. If my device had a DNS entry, I would see the newly discovered hostname name as Display Name in the results.
Given the Scan results, the IP address of the “new” device should be seen in the Discovered device list. However, it doesn’t appear in the list.

If the discovered device had a DNS entry, the device CAN be found in the list using the hostname, however, the IP address in the IP address column is incorrect. Both of those results indicate that the new device has merged with a device that already exists in the discovered device list. And, if the device is marked as being monitored (instead of a black diamond, there is a round indicator) the device is associated with a device in the Monitored device list as well (under My Network).

Error Message

Defect Number

Enhancement Number

Cause

The process of merging is an essential part of the WhatsUp Gold discovery process. When a new discovery is started (through a New Scan, New device, etc.) the devices that are discovered must be associated with devices already in the discovered device tables in the WhatsUp database (unless they are truly new devices, in which case they will be added to the discovered device tables). To merge certain key factors are considered including identity properties of the device, MAC addresses, and IP addresses. When the discovery process finds a match with an existing device, the existing device is updated with any changed information from the device in the newly discovered set of devices. 99% percent of the time, this merging process works as expected. In some cases, merging will result in one device in WhatsUp Gold where two or more devices are expected. By far, the most common reason for this to occur is when two devices (or more) share a common IP address.

The full list of device Merge Reasons can be found HERE.

An easy way to identify the Merge Reason is to view the Merge Info in the Device Properties of the existing Device as shown in this example:

Resolution

Before Proceeding:

Before proceeding with the steps below, please refer to the article Device disappears after discovery to confirm that none of the missing devices have been inadvertently hidden.

This article is written for WhatsUp Gold services running version 2023.1 or higher. If needed, upgrade your WhatsUp Gold server before continuing.

Please Note that the steps below are using an example of merging due to an IP address belonging to both devices. If the merge is caused by a common MAC address, the following steps can be used with the MAC address instead of the IP address.

Step 1: Find the device that contains the IP address of the newly discovered device (the merged device).
The easiest way to find the merged device is to use the filtering option that is part of the Discovered device list. In the Discovered Device list on the upper left, there is a tab called Filters. Make sure that the tab is selected. Type in the IP address of the missing device and click Name/IP as in this example:

A screenshot of a computer Description automatically generated

In this example, the device shown with the filter contains the IP address of the missing device. Notice that the primary IP address is different. Also, the Display Name might be the same as the newly discovered device or might be different (as in this case). Also, note that the device is shown as being monitored and is currently in an UP status. If the newly discovered device merged with a device that already existed in the discovered device list but that device is not set to be monitored, the device would display a black diamond (not monitored). In either case, the device shows a different primary IP address, indicating that a merge occurred.
When the device is highlighted (as above), the discovered device properties will be displayed in the right dialog.

A screenshot of a computer program Description automatically generated

A screenshot of a computer program Description automatically generated

Clicking on the “All names & addresses” dialog will present a popup that shows all Names, IP addresses, and MAC addresses associated with that device. Click on the IP tab.

A screenshot of a computer Description automatically generated

In this example image, the primary IP address of this device is 10.0.0.246, the IP address that was discovered is 10.248.7.26, which already “belongs” to the 10.0.0.246 device. That was the specific reason that the newly discovered device (in this example) merged into the 10.0.0.246 device.
Also, because this device is showing as already being monitored, there is another link called “Monitored Device Properties”. Clicking on this link will open the device properties (from the Monitored device list). An important note is that WhatsUp Gold maintains a set of devices that are discovered and a set of devices that are monitored. A monitored device is always linked to a discovered device.

A screenshot of a computer Description automatically generated

Step 2: Add the IP address(es) or MAC Address(es) that are in common between the new device and the merged device to the IP/MAC Address Exceptions list
The IP/MAC Address Exceptions list can be found under Settings / Discovery setting
A screenshot of a computer Description automatically generated

In the Address Exceptions list click on the plus sign to add your IP address(es) or MAC address(es)

A screen shot of a computer Description automatically generated

In our example above, the IP address of the new device already belongs to a device that has been discovered. By adding the IP address to the Exceptions list, the IP address will not be considered when discovery merging occurs. This will allow the discovery of the new device and have it created as a separate new entry in WhatsUp Gold

A screenshot of a computer Description automatically generated

After adding the IP address or MAC address click OK. If there are multiple IP addresses and/or MAC addresses in common, click the plus sign for each and add each item.
After making changes to the exception list click the X in the dialog to close the list. At this time, WhatsUp Gold will request to restart the discovery and NetworkViewerData services. Please click Restart. If you select to not restart the exception list changes will not be available for discovery.

A screenshot of a computer Description automatically generated

Step 3: Remove the merged device completely from the WhatsUp Gold server.
When a new device merges into an existing device in WhatsUp Gold details from the new device will be added to the device in the discovered list, this can include changing the hostname, additional IP addresses, other device properties, etc. The merged device will often have details that you do not want for that device.
If the device is unmonitored (black diamond) you can simply delete the merged device (as found above using the discovery filter) from the discovered list.
If the device is monitored, click on the “Monitored Device Properties” link from the device selected in discovery.

A screenshot of a computer Description automatically generated

Using that detail find the device in the device list under My Network and click to select the device, right-click on the device, and select Delete Device
In the dialog that results, be sure to select to remove the device from the discovery set of devices as well.

A screenshot of a computer Description automatically generated

Click OK to remove the device.

Step 4: Discover the device that was missing at the start of the process.
The “missing” device can be discovered again at this point. Also, if a device was removed in Step 3, it will need to be discovered as well. Discovering both devices should result in 2 devices being added to the WhatsUp Gold discovery device list. Both devices should be in an unmonitored status.

A close up of a blue and white rectangle Description automatically generated

A close up of a blue and white rectangle Description automatically generated

In this image, the device that was originally merged into another device is now, properly, a separate unmonitored device in the discovered device list. If I was using “New Device” from the Monitored device list the device would appear both in the discovered devices list and the monitored devices list (My Network) and show as monitored.

PLEASE NOTE: If the device is still merging after this process, that indicates that there may be other IP addresses or there are other devices currently in WhatsUp Gold with that IP address. Please review the IP addresses (and MAC addresses) of the device being added to WhatsUp Gold and compare them with devices already added to WhatsUp Gold (on the device side). Add any IP addresses or MAC addresses in common to the IP/MAC address exception list, as above.

Workaround

Notes

Keyword Phrase

missing, merging, vanishing, device, discovery, new scan, scan history, new device

Last Modified Date

11/20/2024 6:40 PM

Devices disappear or incorrect after being discovered (merging into another device)

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