We use game theorectic models to show the lack of incentives in the TCP congestion avoidance algorithm and the consequential systemwide network problems. We then propose a Vickery-Clark-Groves (VCG) mechanism-based access control mechanism for packet traffic. Our mechanism is called "Smart Pay Access Control (SPAC)." We prove both the incentive compatibility and individual rationality of SPAC, which achieves Pareto efficient allocation of network resource. The computing problems are NP-hard for the general VCG mechanism, whereas our mechanism computes the winner's determination problem as fast as a sorting algorithm. The speed of SPAC makes it feasible for the real world usage. As a positive side effect, the mechanism provides the base for a pricing scheme, which we present in the context of the DiffServ architecture for the Internet.