Connecting the wired and wireless networks particularly the Mobile ad hoc Network is interesting in real world situations due to its usefulness and practicality. Different mechanisms have been proposed to integrate MANETs and the Internet. These strategies differ in gateway discovery mechanism, cell switching criteria, ad hoc routing protocol.In this paper, Mobile-IP is integrated with Hierarchical Cluster-Head Gateway Switch Routing (CGSR) Protocol to provide Internet access to the mobile node of the ad hoc Network. This paper discusses a mechanism for selecting an alternate route in case if the Cluster Head is unable to forward the packets to the destination. The proposed framework provides bi-directional connectivity between the MANET and the Internet nodes. A detailed performance comparison is made between the proposed approach and the other three-tier strategies based on mobility of cluster heads and cluster gateways and other network parameters. The experimental results indicate that the proposed architecture has better packet delivery ratio, end-end delay and mobile node-gateway connectivity ratio for providing full bi-directional connectivity.