Aug 20, 2020 - OSPF Sham Links are required when we try to use a backdoor link between two CE routers in MPLS VPN PE CE scenarios.What is OSPF sham link ? OSPF Sham links is a logical inter-area link carried by the super backbone. A Sham links is required only between two VPN sites that belong to the same area and have a backdoor link for backup purposes. OSPF adjacency is established across the sham link. what is BGP ? what is BGP ? what is EIGRP? what is RIPv2? what is MPLS? what is MPLS LDP ? what is MPLS L3 VPN? How to configure MPLS L3 VPN with RIPv2 ? How to configure MPLS L3 VPN with EIGRP ?