The demand for Multi-Protocol Label Switching (MPLS) is increasing day by day in most internet service provider networks. MPLS provides efficient forwarding, routing and switching of traffic flow through the network. MPLS technology has proven itself in providing the required Quality of service (QoS) needed by multimedia and real time application traffic, but it's almost impossible to convert the existing entire huge IPv4 networks to MPLS technology. This paper simulates hybrid IPv4/MPLS networks to overcome multimedia applications QoS problems by obtaining a performance close to pure MPLS network performance. Three different scenarios are investigated using OPNET simulator. Those scenarios are pure IP network, pure MPLS network, and hybrid IP/MPLS network. The simulation results point up the pros and cons of each
scenario in terms of end-to-end delay, delay variation, packet loss ratio, packet delivery ratio, and voice MOS value. In short, pure MPLS network provides the best performance for multimedia traffic but close results can be achieved using hybrid IP/MPLS network.