MPLS is high lightened as the most promising technology for the integrated IP-over ATM backbone networks. Nowadays, one important practical issue in MPLS is how it is capable of providing Differentiated Services. For integrating IP with ATM capable of scalability, MPLS-based ATM switch network can be available, especially for the fast Internet services by adding a Layer 3 routing module to the existing ATM network, and can provide scaleable Internet services to users with various service levels. In this paper, we establish a Queuing model for FE(Forwarding Engine) including service differentiation, which performs IP address lookup in MPLS LER, and evaluate performance of FE with Internet traffic by statistical Internet protocol analysis. Also we take a closer look into our LC(Label Controlled)-ATM switch on which we implement an MPLS controller that can provide both user and provider with relative proportional differentiated service in a feasible and reliable manner.