Minimal cost design of virtual private networks

The cost minimization of virtual private networks (VPN) that use the resources of an underlying transport network is the key factor for their successful implementation. The investigation in this paper is focused on 'network based VPNs', where the operation of the VPN is outsourced to an Internet Service Provider (ISP). The interest in such solutions is generated both by customers seeking to reduce support costs and by ISPs seeking new revenue sources. Solving the cost minimization would allow Internet service providers (ISPs) to define and deploy new VPN services. The basic building block of VPN is the tunnel. A tunnel operates as an overlay across the backbone, and the traffic sent through the tunnel is opaque to the underlying backbone. A VPN end point can terminate multiple tunnels or forward packets between different tunnels. Different tunnels can share the same physical link and traffic belonging to the same VPN tunnel can be carried along different physical links. The multiplexing and management of the VPN tunnels is made possible by core routers supporting the VPN of the underlying network. The novelty of the presented work is the network flow model of VPN mapping on the underlying ISP network. We assume that the VPN topology, the topology of the ISP network and the total utilization cost for all underlying links are known parameters. Based on this, we propose a network management system based on a network flow optimization in order to define the minimal cost link allocation for the VPN tunnels. We provide a simulation of the proposed optimal establishment of VPN tunnels and performance evaluation of the simulation results.