CDN does not calculate connections between infra networks and user networks by increasing physical network. Instead, CDN decentralizes bottlenecked data traffics or contents to main parts of internet network. By this, an amount of traffics passing through Middle-Mile of complicated internet is decreased and CP (Contents Provider)'s server loads are reduced by allocating contents to many distributed servers. In this paper, we proposed an extended Rosary overlay network which is suitable for CDN environment by modification and supplement of Pastry. The proposed Rosary extends Pastry by dividing it into Inter-Pastry and Intra-Pastry to fit for CDN environment, makes application-level multicasting and adopts semi-hash scheme. By adopting geographic layout technology to proximity neighbor selection technology of Pastry, Rosary node was made to act as landmark server.