Use the RANGE statement to add ranges to OSPF areas. OSPF areas can be defined in terms of address ranges. External to the area, a single route is advertised for each address range. For example, if an OSPF area were to consist of all subnets of the class B network 128.185.0.0, it would be defined as consisting of a single address range. The address range would be specified as an address of 128.185.0.0 together with a mask of 255.255.0.0. Outside of the area, the entire subnetted network would be advertised as a single route to network 128.185.0.0.
Ranges can be defined to control which routes are advertised external to an area.
When OSPF is configured not to advertise the range, no interarea routes are advertised for routes that fall within the range. Ranges cannot be used for areas that serve as transit areas for virtual links. This does not prevent AS-external routes from being advertised if used in conjunction with the AS_BOUNDARY statement.
Syntax
>>-Range--IP_address--=--address--Subnet_Mask--=--mask----------> .-Area_Number=0.0.0.0--. .-Advertise=YES-------. >--+----------------------+--+---------------------+----------->< '-Area_Number--=--area-' '-Advertise--=--value-'
Parameters
- IP_Address
- Common subnet portion of IP addresses in this range. Valid values are valid network and subnetwork addresses.
- Subnet_Mask
- Subnet mask with respect to the network range defined in IP_Address.
- Area_Number
- Area number for which to add this range. Valid values are any defined areas.
- Advertise
- Determines whether this range is advertised to other areas. Valid values are YES or NO.