Abstract: Subnet isolation method is very important to solve the traffic interference when a large number of applications execute concurrently for network-on-chip(NoC)based many-core processor.Aiming at the problem that the state-of-the-art subnet isolation routing algorithms are only suitable for some specific types of irregular topological subnets,which reduce the utilization of the on-chip system,a topology model of irregular subnets is presented,and a low-cost isolation routing algorithm(LIRA)is proposed without virtual channels based on the odd-even turn model.LIRA employs the dimensional routing algorithm to transmit packets,until the boundaries of the irregular topological subnets destroy the minimal routing path.Then,LIRA adopts two modes of north-south boundary routing and east-west boundary routing to transmit packets.Experimental results on both synthetic traffic patterns and application traces show that LIRA improves the utilization of the system without decreasing the network performance.