This paper proposes a SIP-based connection management mechanism that supports direct connection and in-direct connection switch method. The main four procedures, i.e., D2D Resource Acquisition, D2D Registration, D2D Communication and D2D Termination, provide D2D connection notification and D2D connection switch method. The underlying concept of the proposed method is to provide a D2D server for D2D connection management and use SIP protocol to notify the D2D devices that have connection requests in order to establish or to switch a direct or in-direct connection.