Creating an OSPFv3 Virtual Link

Create a virtual link if the switch does not connect directly to the backbone. The switch can create automatic virtual links or you can perform this procedure to create virtual links manually. Manual virtual links conserve resources and provide specific control over virtual link placement in your OSPFv3 configuration.

Before you begin

The router must be an ABR to create a virtual router interface.
Change the VRF instance as required to configure OSPFv3 on a specific VRF instance.
Note
Non-default VRFs do not support the configuration of the following parameters:
- OSPFv3 interfaces over IPv6 tunnels
- IPSec on OSPFv3 virtual link interfaces

About this task

Virtual linking is similar to backup redundancy. The switch creates a virtual link for vital traffic paths in your OSPFv3 configuration if traffic is interrupted, such as when an interface cable that provides a connection to the backbone (either directly or indirectly) is disconnected from the switch. Automatic virtual linking ensures that a link is created by using another switch.

OSPF routes cannot be learned through an ABR unless it connects to the backbone directly or through a virtual link.

Procedure

In the navigation tree, expand the following folders: Configuration > IPv6.
Click OSPFv3.
Click the Virtual If tab.
Click Insert.
Specify the ID for the transit area.

The transit area is the common area between two ABRs.
Specify the router ID for the virtual neighbor.

The neighbor ID is the IP router ID of the ABR through which the other ABR must route traffic destined for the backbone.
Click Insert.
Click Refresh to verify that the virtual link is active.

If the state is point-to-point, the virtual link is active. If the state is down, the virtual link is configured incorrectly.

Virtual If field descriptions

Use the data in the following table to use the Virtual If tab.


Name	Description
AreaId	Specifies the ID for the transit area that the virtual link traverses. Do not use 0.0.0.0.
Neighbor	Specifies the router ID of the virtual neighbor.
TransitDelay	Specifies the estimated number of seconds to transmit a link-state update packet over this interface. The default is 1 second.
RetransInterval	Specifies the number of seconds between link-state advertisement retransmissions for adjacencies that belong to this interface. This value also applies to the retransmissions of database description and link-state request packets. The default is 5 seconds.
HelloInterval	Specifies the number of seconds between hello packets that the router sends on this interface. Configure the same value on the virtual neighbor. The default is 10 seconds.
RtrDeadInterval	Specifies the number of seconds after which the neighbor declares the router down if it does not receive hello packets. Configure this value as a multiple of the hello interval. You must configure the same value on the virtual neighbor. The default is 60 seconds.
State	Shows the state of the virtual interface: either down or pointToPoint.
Events	Shows the number of state changes or error events on the virtual link.
LinkScopeLsaCount	Shows the number of link-scope LSAs in the LSDB for the virtual link.
LinkLsaCksumSum	Shows the sum of the checksums for the link-scope LSAs in the LSDB. Use the sum to determine if a change in the LSDB occurs, and to compare the LSDBs of the two routers.