Symptom
When changing the IP address of the diagnostic interface the Firepower Management Center (FMC) shows a warning message: "Modifying the IP Address of Management Interface, might require re-registration of device.Any network connected to this interface will be disconnected. Do you want to continue ?"
This message is misleading because of the following reason because the management interface allocated to the Firepower software is visible in the Lina engine with the nameif "diagnostic" and in the FTD CLISH/Snort engine as the management0 or br1 (only in Firepower Thread Defense (FTD) software running on the ASA hardware). The diagnostic and management0/br1 interfaces can have separate IP addresses. For device registration purposes, the management0 or br1 interface is used. Since the diagnostic interface is not used for device registration, changing its IP address does not require the re-registration of the device.
Conditions
Change the IP addresses of the diagnostics interface on FMC.
Further Problem Description
This is a cosmetic error message and can be ignored.
For more infomration about the FTD management interface refer to the article: https://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-firewalls/212420-configure-firepower-threat-defense-ftd.html
