Inter-processors communication is one of the key issues of the system performance. The ability of networks to continue operating despite failures at minimum cost are major concerns in determining the overall system performance. In this paper, a new irregular multistage interconnection network is proposed named as Irregular Augmented Shuffle Exchange Network-4 (IASEN-4). The Performance of IASEN-4 is measured over some popular MINs in terms of permutation passable, fault-tolerance and cost effectiveness. It has been observed that IASEN-4 provides much better fault tolerance by providing more paths between any pair of source-destination at lesser cost as compared to other popular networks such as IASEN-3, IAON  and IASEN-2. Key Words: Multistage Interconnection Networks, Irregular Augmented Shuffle Exchange Network, Irregular Advance Omega Network, Permutation Passable, Cost-Effectiveness.