Encryption of Internet Protocol (IP) traffic using IP Security (IPSec) at the edge of the enterprise network, in such a way as to support resilient BGP/MPLS IP VPN network designs. The IP traffic is securely tunneled within IPSec tunnels from the edge to the edge of the enterprise network. The IPSec traffic is also tunneled within MPLS tunnels from the edge to the edge of the service provider network. The enterprise network thus manages its own IPSec site-to-site VPN. The service provider thus independently manages its own MPLS network. The result provides an IP VPN or Layer 3 MPLS VPN to the enterprise; the enterprise IPSec network can thus be considered as an overlay to the MPLS service provider network.