An improved Internet gateway discovery and selection scheme in Mobile Ad hoc Network

Integrating nodes in a MANET to the Internet require either a connection to the Internet or they can connect to the Internet through the Internet gateways or servers. For the second case a node in a MANET has to find out the gateway or server to connect to the fixed nodes in the Internet and it can do so either by broadcasting a gateway discovery request message or it may depend on periodic gateway advertisement messages from the gateways. End to end packet delay and throughput are strongly dependent on the time needed to discover the gateways. Hosts in a MANET use number of hops as metric to select a path to a gateway, if all the nodes select its nearest gateway to access the Internet then there may be situations when the network performance degrades because some nodes along the path have too many packets waiting in the queue. This paper presents a novel solution for connecting nodes in ad hoc network to the Internet. Here the gateway replies with an advertisement message which is broadcasted to the whole network in stead of sending a unicast reply to the requestor. We also take into account the traffic load along a path in addition with minimum hop count to select an efficient gateway. The AODV routing protocol has been used for routing in the MANET domain. We investigated our new strategy of gateway discovery and impact of new metric on the gateway selection in NS-2. Simulation results show that our one has better performance having lower delay and fewer packets drop.