Extending Content Delivery Network (CDN) infrastructure that has features of router-based network management system (RNMS) is highly appealing and challenging. It allows developing a CDN architecture based upon standard design to ease interoperability, scalability, performance, and flexibility both on network monitoring and management controlled from a router. To better understand the system model, necessity, and the advantages of RNMS, this paper proposed an algorithm that distributed in to a special router called Service-oriented Router (SoR). The function of algorithm is to manage the effective and efficient number of replica server runs in the network. In CDN, minimizing the number of activated replica servers should be considered in order to reduce the operation cost of the system. We propose a semantic approached algorithm that has function to optimize the selection of active replica servers which managed from SoR. The algorithm has capability to find the best location of replica servers and performs load balancing among replica servers. Our simulation result indicates that the proposed algorithm can efficiently activate the replica servers according to user's request with 33.9% effective compared to other algorithm within about one millisecond RTT increase.