What is used to provide virtual intra-area OSPF connectivity across MPLS VPN backbone so the customer’s traffic will prefer the MPLS VPN backbone over a backdoor OSPF link between the customer’s sites?
A.
OSPF virtual-link
B.
OSPF sham-link
C.
OSPF nssa-link
D.
OSPF stub-link
E.
OSPF demand-circuit
F.
OSPF LSA1-link