Mobile ad hoc networks (MANET) are autonomous

infrastructureless networks that support multi-hop communication through IP routing.MANET and the Internet have many differences.These differences are not only the structure and topology of networks

but also communication patterns of nodes in both networks.Integrating MANET and the Internet into a hybrid network is a challenging problem due to these differences.In order to MANET node to possess Internet connectivity

it must be able to find an Internet gateway.This issue consists of how to find and maintain contact with Internet by gateway.Additionally

how to handover to a more suitable neighboring gateway is also related to this issue.In this paper

we propose the dynamic gateway concept that it acts as an interface between MANET and the Internet.With model analysis

it is proved that the dynamic gateway architecture is appropriate for ad hoc Internet connectivity.Our simulation results show that the performance of networks with dynamic gateways is superior to that of fixed gateway architecture.