OPNET Modeler is the industry's leading environment for network modeling and simulation, allowing you to design and study communication networks, devices, protocols, and applications with unmatched flexibility and scalability. Modeler is used by the world's largest network equipment manufacturers to accelerate the R&D of network devices and technologies such as VoIP, TCP, OSPFv3, MPLS, IPv6, and more; and provides the applications for CDMA2000,UMTS, Wimax, System-in-the-Loop, HLA and etc.