Configuring ranges on an ABR to reduce advertising to the backbone

Optional: Configuring ranges does the following to reduce inter-area advertising:

Summarizing routes: Enable a routing switch operating as an ABR to use a specific IP address and mask to summarize a range of IP addresses into a single route advertisement for injection into the backbone. This results in only one address being advertised to the network instead of all the addresses within that range. This reduces LSA traffic and the resources needed to maintain routing tables.
Blocking routes: Prevent an ABR from advertising specific networks or subnets to the backbone area.

Each OSPF area supports up to 8 range configurations.