OSPF Areas (Part 5) - NSSA
Links:
RFC 3101 - The OSPF Not-So-Stubby Area (NSSA) Option
RFC 1587 - The OSPF NSSA Option (Obsoleted by 3101)
RFC 2740 – OSPF for IPv6
Cisco - OSPF Not-So-Stubby Area (NSSA)
Breakdown of the NSSA (Not-So-Stubby-Area) Area:
Redistribution allowed by ASBRs in NSSA areas
NSSA ASBRs generate Type-7 LSAs for all external routes
Appears in the routing table as N1 or N2 external.
NSSA ABRs convert
Source: OSPF Areas (Part 5) - NSSA (//)
From http://blog.movingonesandzeros.net/