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# Display OSPF routing information on Switch C
[SwitchC] display ospf routing
OSPF Process 1 with Router ID 10.4.1.1
Routing Table
Routing for network
Destination Cost Type NextHop AdvRouter Area
0.0.0.0/0 4 Inter 10.2.1.1 10.2.1.1 0.0.0.1
10.2.1.0/24 3 Transit 0.0.0.0 10.2.1.1 0.0.0.1
10.3.1.0/24 7 Inter 10.2.1.1 10.2.1.1 0.0.0.1
10.4.1.0/24 3 Stub 10.4.1.1 10.4.1.1 0.0.0.1
10.5.1.0/24 17 Inter 10.2.1.1 10.2.1.1 0.0.0.1
10.1.1.0/24 5 Inter 10.2.1.1 10.2.1.1 0.0.0.1
Total nets: 6
Intra area: 2 Inter area: 4 ASE: 0 NSSA: 0
The output shows that a default route replaces the AS external route.
# Configure Area 1 as a totally stub area.
[SwitchA] ospf
[SwitchA-ospf-1] area 1
[SwitchA-ospf-1-area-0.0.0.1] stub no-summary
[SwitchA-ospf-1-area-0.0.0.1] quit
[SwitchA-ospf-1] quit
# Display OSPF routing information on Switch C.
[SwitchC] display ospf routing
OSPF Process 1 with Router ID 10.4.1.1
Routing Table
Routing for network
Destination Cost Type NextHop AdvRouter Area
0.0.0.0/0 4 Inter 10.2.1.1 10.2.1.1 0.0.0.1
10.2.1.0/24 3 Transit 0.0.0.0 10.4.1.1 0.0.0.1
10.4.1.0/24 3 Stub 10.4.1.1 10.4.1.1 0.0.0.1
Total nets: 3
Intra area: 2 Inter area: 1 ASE: 0 NSSA: 0
The output shows that inter-area routes are removed, and only one external route (a default
route) exists on Switch C.
OSPF NSSA area configuration example
Network requirements
As shown in Figure 28:
• Configure OSPF on all switches and split AS into three areas.
• Configure Switch A and Switch B as ABRs to forward routing information between areas.
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