ecall that a not-so-stubby area (NSSA) is useful when we have an
area that requires the injection of external routes, although we still want to eliminate the injection of Type 5 LSAs. Figure 5.6 presents such a scenario. In Area 1, we want to prevent Area 0 from injecting Type 5 LSAs, yet we still need external routes from the RIP routing process to be injected into Area 1. The solution to these requirements is to make Area 1 an NSSA.
F I G U R E 5 . 6
OPSF configuration example continued--not-so-stubby area configuration