Mobile Ad hoc Network (MANET) is a kind of wireless networks architecture, which is an infrastructureless, autonomous, stand-alone network. Therefore, MANET can be flexibly and simply deployed in almost any environment. But it has a limited wireless coverage and limited connectivity that is exclusive to the MANET boundary. The growth of the Internet and its services and applications and the trend in fourth generation (4G) wireless networks toward full-IP networks, lead to an increasing demand for enabling MANET nodes to connect to Internet and use its services and applications. Mobile IP and IP micro-mobility protocols enable the mobile host to access Internet and change points of attachment without losing the connection. So, with the cooperation between MANET routing protocols and IP mobility protocol, Internet connectivity to MANET nodes can be achieved. In this paper, we propose an integrated network architecture to extend the cellular IP access network to multiple MANETs. We also propose an integration routing protocol for connecting MANET to Cellular IP Access network and Internet. The proposed protocol supports mobile nodes mobility between different MANETs.