MPLS VPNs are one of the most widely deployed VPN architectures in the global Internet. However, a major prerequisite for MPLS VPN is the support for MPLS in all the provider core routers. The situation becomes complicated when service providers themselves use a backbone carrier to bring connectivity to their networks since the ability of the backbone to support MPLS connectivity would be crucial to the service provider. MPLS-over-GRE (generic routing encapsulation) tunnels are a new concept that has been proposed to bring MPLS connectivity between networks that are connected by an IP-only network. The aim of the current paper is to evaluate the performance of MPLS carrier supporting carrier configuration with and without MPLS-over-GRE tunnels.