Content Delivery Networks (CDN) are overlay network of servers being used to deliver growing traffic demands on the Internet. As a result, CDNs are facing ever-increasing operating costs. Internet Service Providers (ISP) charge CDNs on server traffic, computed using common usage-based charging models, e.g. 95th Percentile charging. We propose Network Cost Aware Request Routing, NetReq, that assign user requests to reduce server charging volume. We compare NetReq against nearest-available server request routing in large scale simulations for both web and multicast traffic requests. NetReq reduces charging volume for both traffic request types, thereby reducing cost. NetReq provides comparable network performance for multicast traffic by introducing end-to-end delay as a constraint in the request-routing. NetReq marginally increases network performance for web traffic, when content maybe available at every server.