SHORTEST PATH PROBLEM: USING ANT COLONY OPTIMIZATION TO SOLVE THE SHORTEST PATH PROBLEM IN ROUTING PACKETS IN A NETWORK. A. Emmanuel 1 , D. Yakmut 2 1, 2 Department of Computer Science, Federal University, Lafia, Nasarawa State, Nigeria ----------------------------------------------------------------***----------------------------------------------------------- Abstract – As packets travel in a network, there needs to be an efficient routing algorithm to provide packets transport from source to destination with high bandwidth and lower routing delay time, this being a problem, the shortest path problem, the shortest and best route is the best solution to this kind of problem, anytime a packet transaction occurs in a network. The Ant Colony Optimization (ACO) is a heuristic algorithm which has been proven a successful technique and applied to a number of combinatorial optimization (CO) problems including the shortest path (SP) problem. In this project, the ant colony optimization (ACO) technique is used to find the shortest path (SP) in the routing problem of a network. The algorithm is uses two different metrics (bandwidth and routing delay) to determine the optimal route path (best route). The proposed method is used to determine the optimal path from source to destination. The Ant colony decision for any such routing problem must be made under the current network conditions, decisions that minimize delay and maximum bandwidth for each link (node) to selected optimal link. Key Words: Ant Colony Optimization, Shortest path, Best route, ACO, Ant, Network Routing Problem. 1. INTRODUCTION The Ant Colony Optimization (ACO) metaheuristic is a versatile optimization approach based on the observation of the behaviour of ants. As a result of numerous analyses, ACO has been applied to solving various combinatorial problems. The ant colony metaheuristic proves itself to be efficient in solving Non-deterministic Polynomial- time (NP) hard problems, often generating the best solution in the shortest amount of time. However, not enough attention has been paid to ACO as a means of solving problems that have optimal solutions, which can be found using other methods. The shortest path problem is undoubtedly one of the aspects of great significance to navigation in networks communications and telecommunications. It is used, amongst others, for determining the shortest route between two geographical locations, for routing in packet networks, and to balance and optimize network utilization. There are already many accepted routing algorithms to find the shortest path and also to increase the throughput of the network. In this paper, a routing algorithm has been proposed which may be applied in large network structure with heavy load. The algorithm proposed here is selecting the path of the data packets guided by the shortest path but with a probabilistic nature. The goal of every network routing algorithm is to direct the traffic from source to the destination maximizing the network performance. Mukherjee and Acharyya (2010). Communication networks can be classified as either circuit switched or packet switched. Circuit-switched networks rely on a dedicated connection from source to destination which is made once at start-up and remains constant until the teardown of the connection. Packet switched networks work quite