OSPF Areas: Totally NSSA:
· Totally NSSA area is a Totally-stubby-area, which has external connectivity.
· Default-route gets injected into this by an ABR.
Network topology and Configs are same as the previous post (Stub Area).
· In the previous NSSA post, we learnt that Type-5 LSAs are blocked in NSSA area and redistributed routes inside NSSA area will come as Type-7 LSAs.
· These Type-7 LSAs are valid only inside NSSA area and ABR converts them into Type-5 LSAs before sending them to other areas.
Now, let’s configure Area 1 as Totally NSSA:
R2(config)#router ospf 1
R2(config-router)#area 1 nssa no-summary
If we check R3’s routing table, we shouldn’t see any External and Inter-area routes:
R3#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is 220.127.116.11 to network 0.0.0.0
18.104.22.168/32 is subnetted, 1 subnets
C 22.214.171.124 is directly connected, Loopback33
126.96.36.199/32 is subnetted, 1 subnets
C 188.8.131.52 is directly connected, Loopback0
184.108.40.206/24 is subnetted, 1 subnets
C 220.127.116.11 is directly connected, Serial1/1
18.104.22.168/32 is subnetted, 1 subnets
O 22.214.171.124 [110/65] via 126.96.36.199, 00:27:38, Serial1/1
188.8.131.52/32 is subnetted, 1 subnets
C 184.108.40.206 is directly connected, Loopback133
O*IA 0.0.0.0/0 [110/65] via 220.127.116.11, 00:01:27, Serial1/1
· We don’t see any Inter-area routes.
· Intra-area routes will still be there since they are local to the area.
· We also see one default route injected into Totally NSSA area by an ABR R2.