Any precautions when changing LAN from /24 to /23 on CARP setup.

[k22]

Hello -
I have two units in a CARP setup. I need to change a LAN network from /24 to /23. Any precautions I should take or is this fairly straightforward?

[Derelict]

What is your LAN subnet currently?

[k22]

10.10.11.0/24
I want to change to 10.10.10.0/23.

[Derelict]

Yeah, that gets kind of messy. What are your CARP/interface addresses? What is your DHCP Pool? Any other statics/DHCP static mapping ranges?

(This is why I always put my stuff on CIDR boundaries like 8, 16, 24, 32 instead of, say, 11.)

[k22]

CARPs are 10.10.11.2 and 10.10.11.3.
My pool is 10.10.11.12 - 10.10.11.250.
I have some statics 10.10.11.5 - 10.10.11.10.

[Derelict]

OK so those are going to be in the middle of your new range so you are going to have to either change them or do multiple DHCP pools.

You need to realize that the network and broadcast addresses of all your clients are going to be mismatched.

You might want to, in advance, temporarily shorten your DHCP lease time to minimize how long your clients have the old settings.

Is pfSense your DHCP server? Is it configured in HA mode?

[k22]

Shortened the dhcp lease per suggestion and made the changes. Everything went smoothly. Many thanks for all the help.