Setting an specific IP address for a WAN port

RouterOS Beginner Basics
1

Hi,

I have setup a ccr1009 to loadbalance 4 WANs, 2 of these WANs get the IP address from the ISP router, which can change. So is there a way where I can manually set ether5 port to a specific address, so I know it always has that address.

So from the example below I have to make sure the ISP routers gives ether5 the address 192.168.2.21/24

/ip address
add address=192.168.2.21/24 network=192.168.2.0 broadcast=192.168.2.255 interface=ether5_WAN1