Why the Number of Routes in the OSPF Routing Table of the OSPF VPN Multi-instance Is Less than the Predicted Number?
In the OSPF VPN multi-instance, loops may occur if PEs and CEs learn BGP and OSPF routes from each other. You can set the DN in Type3, Type5, or Type7 LSAs advertised by PEs to 1 so that CEs ignore the LSAs with the DN value of 1. These LSAs are not used in route calculation, which prevents loops.
If the preceding method is used to prevent loops, the number of routes in the OSPF routing table is less than the predicted number. To use the LSAs with DN 1 in route calculation, run the vpn-instance-capability simple command on CEs to disable routing loop detection.