Assigning an IP address to an interface
An interface must have an IP address to communicate with other hosts. You can either manually assign an IP address to an interface, or configure the interface to obtain an IP address through BOOTP or DHCP. If you change the IP address assignment method, the new IP address will overwrite the previous address.
An interface can have one primary address and multiple secondary addresses.
Typically, you need to configure a primary IP address for an interface. If the interface connects to multiple subnets, configure primary and secondary IP addresses on the interface so the subnets can communicate with each other through the interface.