Changing the network mask on the mgmt interface in a FTD 3140 cluster

[darkbeer]

Hi Guys,

I have a running cluster with a pair of FTD 3140. I discovered that the network mask of the mgmt interface is wrong. Should be changed from a /23 to a /24. The ip address will not change. Is this possible somehow on the CLI without breaking the cluster and removing the FTD from the FMC ?

Thanks a lot

[MHM Cisco World]

If there is NO overlapping then keep it as it

If there is overlapping 

Check guide below be careful friend 

MHM

[MHM Cisco World]

https://www.cisco.com/c/en/us/td/docs/security/firepower/70/configuration/guide/fpmc-config-guide-v70/device_management_basics.html

Read guide and Be careful friend.

MHM

[MHM Cisco World]

Why it issue change mgmt of fpr ?

The mgmt interface use to connect to fmc' any wrong make ftd not connect to fmc and maybe config loss.

Check guide read about how ftd register fmc 

Read about NAT-ID 

Then decide to go ahead 

MHM

[Marius Gunnerud]

You should be able to change the management IP and/or subnet on the FTD without having issues.  Documentation states that you could experience several minutes without connectivity before connectivity is restored so be patient.

As always, when doing these types of changes you should either have direct console access or out-of-band console access to the FTD device.  Also, I highly recommend taking a device backup before performing this incase you need to restore the device to its former state.