The mobility management cost of mobility support protocols is studied. Firstly a suitable network model is proposed and the signaling overhead brought to network in order to support MHs’ (mobile host) mobility using various mobility support protocols is analyzed theoretically. On this base, a numerical simulation method is applied to compare the signaling overhead when only using mobile IP with introducing hierarchical mobility and when applying different micro-mobility protocols such as MIP-RR, CIP and HAWAII. The results show that introducing hierarchical mobility decreases the network signaling overhead observably comparing with only using mobile IP. In different micro-mobility protocols, the route maintenance strategy of deleting old routes explicitly brings less signaling overhead than frequently sending refresh messages periodically, and the route update method of sending route update messages to crossover MRA (mobile routing Agent) brings less signaling overhead than sending messages to GW (gateway).