Configuring virtual links

If an Area Border Router (ABR) does not have a physical link to a backbone area, a virtual link can be configured between that ABR and another device within the same area that has a physical link to a backbone area.

Before you begin

About this task

A virtual link is configured, and a virtual link endpoint on two devices, ABR1 and ABR2, is defined.

Procedure

On ABR1, enter the configure terminal command to access global configuration mode.
```
device# configure terminal
```
Enter the router ospf command to enter OSPF router configuration mode and enable OSPFv2 on the device.
```
device(config)# router ospf
```

Enter the area command to assign an OSPFv2 area ID.

device(config-router-ospf-vrf-default-vrf)# area 0

Enter the area command to assign an OSPFv2 area ID.

device(config-router-ospf-vrf-default-vrf)# area 1

Enter the area virtual-link command and the ID of the OSPFv2 device at the remote end of the virtual link to configure the virtual link endpoint.
```
device(config-router-ospf-vrf-default-vrf)# area 1 virtual-link 10.2.2.2
```
On ABR2, enter the configure terminal command to access global configuration mode.
```
device# configure terminal
```
Enter the router ospf command to enter OSPFv2 router configuration mode and enable OSPFv2 on the device.
```
device(config)# router ospf
```

Enter the area command to assign an OSPFv2 area ID.

device(config-router-ospf-vrf-default-vrf)# area 1

Enter the area command to assign an OSPFv2 area ID.

device(config-router-ospf-vrf-default-vrf)# area 2

Enter the area virtual-link command and the ID of the OSPFv2 device at the remote end of the virtual link to configure the virtual link endpoint.
```
device(config-router-ospf-vrf-default-vrf)# area 1 virtual-link 10.1.1.1
```

Example

The following example configures a virtual link between two devices.

ABR1:
device1# configure terminal
device1(config)# router ospf
device1(config-router-ospf-vrf-default-vrf)# area 0
device1(config-router-ospf-vrf-default-vrf)# area 1
device1(config-router-ospf-vrf-default-vrf)# area 1 virtual-link 10.2.2.2

ABR2:
device2# configure terminal
device2(config)# router ospf
device2(config-router-ospf-vrf-default-vrf)# area 1
device2(config-router-ospf-vrf-default-vrf)# area 2
device2(config-router-ospf-vrf-default-vrf)# area 1 virtual-link 10.1.1.1