Usage Scenario
When OSPF/OSPFv3 VPN multi-instance is deployed on a multi-VPN-instance CE (MCE), if the DN bit is set in Type 3, Type 5, or Type 7 LSAs or the route tag carried in Type 5 or Type 7 LSAs is the same as the locally configured route tag, these routes cannot be calculated because loop detection is performed during OSPF/OSPFv3 route calculation. In this case, you can run the vpn-instance-capability simple command to disable OSPF/OSPFv3 routing loop detection and enable the devce to calculate all OSPF/OSPFv3 routes without checking the DN bit or route tag.
If VPN multi-instance is supported on a multi-VPN-instance CE (MCE) device, routing loop detection must be disabled. The
vpn-instance-capability simple command takes effect only in OSPF/OSPFv3 VPN instances.
Prerequisites
OSPF/OSPFv3 VPN multi-instance has been deployed on an MCE using the ospf vpn-instance command.
Configuration Impact
- After the vpn-instance-capability simple command is run on an MCE, the MCE will not become an ABR if OSPF or OSPFv3 backbone area 0 is not configured.
- If the import-route bgp command is run in the OSPF process bound to a VPN instance, IBGP routes will not be imported to the VPN process after the vpn-instance-capability simple command is run unless permit-ibgp is specified in the import-route bgp command.
- After the vpn-instance-capability simple command is run, OSPF/OSPFv3 routes imported by BGP do not carry the OSPF/OSPFv3 domain ID, OSPF/OSPFv3 route type, or OSPF/OSPFv3 router ID.
- By default, when BGP imports an OSPF or OSPFv3 route, the Multi_Exit Discriminator (MED) value (similar to the metric used in an IGP) is the OSPF cost plus 1. After the vpn-instance-capability simple command is run, the MED value is changed to the OSPF/OSPFv3 cost value. As a result, the MED values of the OSPF or OSPFv3 routes imported by BGP change, affecting BGP route selection.
Precautions
The undo vpn-instance-capability simple command cannot be used to enable OSPF/OSPFv3 routing loop detection in a scenario without MCEs.