Mobility management is one of the core requirements of the IPv6 based NGN to provide seamless handover services to mobile enti-ties. In this regard, IETF has proposed protocols like Mobile IPv6 (MIPv6), Fast MIPv6 (FMIPv6) and Hierarchical MIPv6 (HMIPv6) to provide efficient mobility services. Due to the lack of deploy-ment, there is not enough empirical data available to determine the efficacy of these protocols in the context of NGN. For this pur-pose, there is a need to develop an accurate and reliable simula-tion framework with the help of which the users can quickly test the validity of such protocols under a variety of network and load conditions. The simulation framework should also allow the user to rapidly develop and test prototype solutions and algorithms for attaining optimum performance goals. In this paper we present the logic, design and performance results of an OMNeT++ based Mobility Management Simulation Engine for IPv6 networks, which enables the user to accurately test the performance of protocols such as MIPv6, FMIPv6 and HMIPv6, and their possible combination on a single unified platform.