Assigning an area range
Ranges for an area can be assigned. Ranges allow a specific IP address and mask to represent a range of IP addresses within an area, so that only that reference range address is advertised to the network, instead of all the addresses within that range. Each area can have up to 32 range addresses.
The following example defines an area range for subnets on 10.0.0.10 and 10.0.0.20.
device# configure terminal device(config)# router ospf device(config-ospf-router)# area 10.0.0.10 range 10.45.0.0 10.255.0.0 device(config-ospf-router)# area 10.0.0.20 range 10.45.0.0 10.255.0.0