Implementation and performance analysis of the gateway discovery approaches in the integrated MANET-Internet scenario

Most of the research in the field of ad hoc network is limited to stand-alone isolated networks. In order to facilitate the users with the huge pool of resources together with the global services available from the Internet and for widening the coverage area of the MANET there is a growing need to integrate these ad hoc networks to the Internet. For this purpose we need gateways which act as bridges between these two different protocol architectures. The gateway discovery in hybrid network is considered as a critical and challenging task and with decreasing pause time and greater number of sources it becomes even more complex. Due to the scarcity of network resources in MANET, the efficient discovery of the gateway becomes a key issue in the design and development of future hybrid networks. In this paper the AODV reactive routing protocol is extended to support the communication between the MANET and the Internet. We have described the design and implementation of the various gateway discovery approaches and carried out a systematic simulation based performance evaluation of them using NS2 under different network scenarios. The performance differentials are analyzed on the basis of three metrics - packet delivery fraction, average end-to-end delay and normalized routing load.