New architecture and algorithms for fast construction of hose-model VPNs

Hose-model virtual private networks (VPNs) provide customers with more flexibility in specifying bandwidth requirements than pipe-model VPNs. Many hose-model VPN provisioning algorithms have been proposed, and they focus on the bandwidth efficiency in the construction of a single hose-model VPN. In practice, however, VPNs come and go and the dynamics will affect the performance of these VPN provisioning algorithms. If the frequency of adding and deleting VPNs is high, these algorithms will have a scalability problem. We propose in this paper a new network architecture for dynamic VPN construction. In the proposed architecture, adding a new VPN is much simpler and faster, and all that is required is to check if the edge routers have enough bandwidth. There is no need to check the bandwidth left on each internal link because the architecture guarantees that as long as the edge routers have enough capacities to accept the VPN, the internal links will never experience overflow caused by adding the new VPN. We present a linear programming formulation for finding the optimal routing that maximizes the amount of admissible VPN traffic in the network. We then exploit the underlying network flow structure and convert the linear programming problem into a subgradient iterative search problem. The resulting solution is significantly faster than the linear programming approach.