Bandwidth optimization is considered when several classes of Internet traffic are served in Generalized Processor Sharing (GPS) servers. Internet traffic shows self-similar patterns that make it difficult to obtain analytical performance in GPS. Thus, for performance estimation of different classes of traffic, we use fluid simulation techniques that can reduce the simulation complexity, compared to packet-level simulation. Using the relationship between the guaranteed bandwidth vector and the corresponding performance, we propose a bandwidth optimization problem to minimize the total bandwidth such that performance requirements are satisfied. We use an exterior penalty function method to solve the optimization problem. However, a penalized objective function may have local minimum which is not a global minimum. Thus, we propose a new methodology to circumvent the limitation of the exterior penalty function method.