OSPF virtual link configuration example
Network requirements
As shown in Figure 30, configure a virtual link between Switch B and Switch C to connect Area 2 to the backbone area. After configuration, Switch B can learn routes to Area 2.
Figure 30: Network diagram
Configuration procedure
Configure IP addresses for interfaces. (Details not shown.)
Enable OSPF:
# Configure Switch A.
<SwitchA> system-view [SwitchA] ospf 1 router-id 1.1.1.1 [SwitchA-ospf-1] area 0 [SwitchA-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchA-ospf-1-area-0.0.0.0] quit [SwitchA-ospf-1] quit
# Configure Switch B.
<SwitchB> system-view [SwitchB] ospf 1 router-id 2.2.2.2 [SwitchB-ospf-1] area 0 [SwitchB-ospf-1-area-0.0.0.0] network 10.1.1.0 0.0.0.255 [SwitchB-ospf-1-area-0.0.0.0] quit [SwitchB-ospf-1] area 1 [SwitchB–ospf-1-area-0.0.0.1] network 10.2.1.0 0.0.0.255 [SwitchB–ospf-1-area-0.0.0.1] quit [SwitchB-ospf-1] quit
# Configure Switch C.
<SwitchC> system-view [SwitchC] ospf 1 router-id 3.3.3.3 [SwitchC-ospf-1] area 1 [SwitchC-ospf-1-area-0.0.0.1] network 10.2.1.0 0.0.0.255 [SwitchC-ospf-1-area-0.0.0.1] quit [SwitchC-ospf-1] area 2 [SwitchC–ospf-1-area-0.0.0.2] network 10.3.1.0 0.0.0.255 [SwitchC–ospf-1-area-0.0.0.2] quit [SwitchC-ospf-1] quit
# Configure Switch D.
<SwitchD> system-view [SwitchD] ospf 1 router-id 4.4.4.4 [SwitchD-ospf-1] area 2 [SwitchD-ospf-1-area-0.0.0.2] network 10.3.1.0 0.0.0.255 [SwitchD-ospf-1-area-0.0.0.2] quit [SwitchD-ospf-1] quit
# Display the OSPF routing table on Switch B.
[SwitchB] display ospf routing OSPF Process 1 with Router ID 2.2.2.2 Routing Table Topology base (MTID 0) Routing for network Destination Cost Type NextHop AdvRouter Area 10.2.1.0/24 2 Transit 10.2.1.1 3.3.3.3 0.0.0.1 10.1.1.0/24 2 Transit 10.1.1.2 2.2.2.2 0.0.0.0 Total nets: 2 Intra area: 2 Inter area: 0 ASE: 0 NSSA: 0
The output shows that Switch B does not have routes to Area 2 because Area 0 is not directly connected to Area 2.
Configure a virtual link:
# Configure Switch B.
[SwitchB] ospf [SwitchB-ospf-1] area 1 [SwitchB-ospf-1-area-0.0.0.1] vlink-peer 3.3.3.3 [SwitchB-ospf-1-area-0.0.0.1] quit [SwitchB-ospf-1] quit
# Configure Switch C.
[SwitchC] ospf 1 [SwitchC-ospf-1] area 1 [SwitchC-ospf-1-area-0.0.0.1] vlink-peer 2.2.2.2 [SwitchC-ospf-1-area-0.0.0.1] quit [SwitchC-ospf-1] quit
# Display the OSPF routing table on Switch B.
[SwitchB] display ospf routing OSPF Process 1 with Router ID 2.2.2.2 Routing Table Topology base (MTID 0) Routing for network Destination Cost Type NextHop AdvRouter Area 10.2.1.0/24 2 Transit 10.2.1.1 3.3.3.3 0.0.0.1 10.3.1.0/24 5 Inter 10.2.1.2 3.3.3.3 0.0.0.0 10.1.1.0/24 2 Transit 10.1.1.2 2.2.2.2 0.0.0.0 Total nets: 3 Intra area: 2 Inter area: 1 ASE: 0 NSSA: 0
The output shows that Switch B has learned the route 10.3.1.0/24 to Area 2.