Network Management

Fix false 'In use' status for available IP addresses due to empty MAC addresses in IPAM module

This article explains how to configure IPAM to ignore empty MAC addresses in the ARP table.

First published date

4/2/2020 1:05 AM

Last published date

3/6/2025 5:33 PM

Overview

This issue happens where IPs that were not in use are being flagged as 'Used' during a neighbor scan on the subnet and IPAM finds an IP entry in the ARP cache of the scanned device that has an empty MAC or 00-00-00-00-00-00. 

Product section

IP Address Manager

Cause

When IPAM polls or retrieves the MAC address from the ARP table of a network device, the presence of an empty MAC address prevents IPAM from accurately displaying the correct IP status on the Manage Subnets & IP Addresses page, causing IPs that are actually available to be marked as in use. 

Resolution

Follow the below steps to resolve this issue:

  1. Access the URL: https://<OrionServer>/Orion/Admin/AdvancedConfiguration/Global.aspx
    Example: https://<server_name>:8787/Orion/Admin/AdvancedConfiguration/Global.aspx
  2. Choose the Global tab to apply the setting to all servers, or select a specific server.

3. Search for IPAM and check the box for SkipEmptyMAC

4. Click Save.

5. Restart the Orion services. This will cause IPAM to automatically skip all IPs in the ARPcache that have an empty MAC.

6. Re-add the problematic subnets and check again.