OSPF NSSA area configuration example
Network requirements
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.
Configure Area 1 as an NSSA area and configure Switch C as an ASBR to redistribute static routes into the AS.
Figure 26: Network diagram
Configuration procedure
Configure IP addresses for interfaces.
Enable OSPF (see "Basic OSPF configuration example").
Configure Area 1 as an NSSA area:
# Configure Switch A.
<SwitchA> system-view [SwitchA] ospf [SwitchA-ospf-1] area 1 [SwitchA-ospf-1-area-0.0.0.1] nssa default-route-advertise no-summary [SwitchA-ospf-1-area-0.0.0.1] quit [SwitchA-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view [SwitchC] ospf [SwitchC-ospf-1] area 1 [SwitchC-ospf-1-area-0.0.0.1] nssa [SwitchC-ospf-1-area-0.0.0.1] quit [SwitchC-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 Tables Routing for Network Destination Cost Type NextHop AdvRouter Area 0.0.0.0/0 65536 Inter 10.2.1.1 10.2.1.1 0.0.0.1 10.2.1.0/24 65535 Transit 10.2.1.2 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
![[NOTE: ]](images/note.png) | NOTE: To allow Switch C in the NSSA area to reach other areas within the AS, you must provide the keyword default-route-advertise for the nssa command issued on Switch A (the ABR) so that Switch C can obtain a default route. Configuring the nssa command with the keyword no-summary on Switch A can reduce the routing table size on NSSA Switches. On other NSSA Switches, you only need to configure the nssa command. | |
Configure route redistribution:
# Configure Switch C to redistribute static routes.
[SwitchC] ip route-static 3.1.3.1 24 10.4.1.2 [SwitchC] ospf [SwitchC-ospf-1] import-route static [SwitchC-ospf-1] quit
# Display OSPF routing information on Switch D.
<SwitchD> display ospf routing OSPF Process 1 with Router ID 10.5.1.1 Routing Tables Routing for Network Destination Cost Type NextHop AdvRouter Area 10.2.1.0/24 22 Inter 10.3.1.1 10.3.1.1 0.0.0.2 10.3.1.0/24 10 Transit 10.3.1.2 10.3.1.1 0.0.0.2 10.4.1.0/24 25 Inter 10.3.1.1 10.3.1.1 0.0.0.2 10.5.1.0/24 10 Stub 10.5.1.1 10.5.1.1 0.0.0.2 10.1.1.0/24 12 Inter 10.3.1.1 10.3.1.1 0.0.0.2 Routing for ASEs Destination Cost Type Tag NextHop AdvRouter 3.1.3.0/24 1 Type2 1 10.3.1.1 10.2.1.1 Total Nets: 6 Intra Area: 2 Inter Area: 3 ASE: 1 NSSA: 0The output shows an external route imported from the NSSA area exists on Switch D.