In this paper, the filterless optical network concept is presented and explored through a number of filterless solution examples. In the first part, the filterless network concept is presented and analyzed through a comparative case study. In the second part, the filterless network design problem is defined and a filterless network design tool based on metaheuristics is presented. In the third part of this presentation, filterless network solutions are proposed for a number of core network topologies and compared to active photonic network solutions from the point of view of cost and performance. The results show that cost-effective filterless solutions can be found for different network sizes and topologies. The results of a comparative study show that filterless networks represent a cost-effective and reliable alternative to active optical switching network solutions.