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DES-7200 Configuration Guide Chapter 4 OSPF
Configuration
4-57
SwitchD#show ip route
Codes: C - connected, S - static, R - RIP, B - BGP
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
Gateway of last resort is no set
S 172.10.10.0/24 [1/0] via 192.168.6.2
O IA 192.168.1.0/24 [110/2] via 192.168.3.1, 00:03:20, GigabitEthernet 0/3
O IA 192.168.2.0/24 [110/3] via 192.168.3.1, 00:03:20, GigabitEthernet 0/3
C 192.168.3.0/24 is directly connected, GigabitEthernet 0/3
C 192.168.3.2/32 is local host.
O IA 192.168.5.0/24 [110/4] via 192.168.3.1, 00:03:20, GigabitEthernet 0/3
C 192.168.6.0/24 is directly connected, GigabitEthernet 0/4
C 192.168.6.1/32 is local host.
From the above information, we can see that the AS external routes imported by
other areas cannot reach this area when the native area of Switch D is a NSSA
area.
Step 3: Display the routing information of NSSA area while configuring the
"no-summary" attribute of NSSA area on Switch B (ABR).
SwitchD#show ip route
Codes: C - connected, S - static, R - RIP, B - BGP
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
Gateway of last resort is 192.168.3.1 to network 0.0.0.0
O*IA 0.0.0.0/0 [110/2] via 192.168.3.1, 00:00:40, GigabitEthernet 0/3
S 172.10.10.0/24 [1/0] via 192.168.6.2
C 192.168.3.0/24 is directly connected, GigabitEthernet 0/3
C 192.168.3.2/32 is local host.
C 192.168.6.0/24 is directly connected, GigabitEthernet 0/4
C 192.168.6.1/32 is local host.
From the above information, we can see that after configuring "no-summary"
attribute on the ABR of NSSA area, the routing table entries are further reduced,
and the inter-area routes are replaced by one default route.