Areas
LISPS are only sent within an area
An area has a name consisting of up to 3 (net, mask) pairs
It is best if all addresses in the area match one of the area addresses, and no addresses outside the area match
Purpose of area addresses:
To assure neighbors agree on area, so that areas don’t accidentally merge
Used as default summary for area
Filtering of SAP and routes, and summarization of network numbers, can be done at area boundaries