The explosive growth of the Internet combined with the widespread availability of highly mobile small hosts in the form of laptop and palmtop computers, and personal digital assistants, has created a big demand for the concept of Mobile IP. In the base Mobile IP, if the distance between the visited network and the home network of the mobile node is large, the signaling delay for these registrations may be long. Also the two main problems faced are the loss of registration packets and crashes of entities that maintain location caches. Therefore to solve this problem, the solution for performing registrations locally in the visited domain in order to reduce registration delay and to support micro mobility is proposed. In this paper, we propose that a hierarchical structure may be helpful to fast handoff in mobile environments. In company with the fast handoff, reliability is a great concern to the designers of mobile computing systems.