Let’s think that there is an area after area 1, and I want that area to receive the LSA type 5 external. If you do area 1 as a totally stub area, then type 5 (as well as type 3) will be blocked. What we can do is to make area 1 as a NSSA, then you will have LSA type 7 allowing the external routes to pass, then the area after area 1 can receive them as type 5. Also, LSA type 3 will not be blocked. That’s the whole idea ????

Let’s configure area 1 as a NSSA.

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Let’s check the LSDB on R1, we should have LSA type 7 for the external route.

Here I see the LSA type 3 and LSA type 7 in the LSDB. Let’s check the routing table of R1.

Here they are ????!!!!

Again, if you have an area after area 1 then it will receive the LSA type 5 external.

I will remove the NSSA configuration for the next LAB.

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