A network architecture includes one or more feature servers and control servers in a control plane that is logically separate from a data plane that includes forwarding elements. Feature servers facilitate adding network-based functionality in a centralized way that is has better scalability than the traditional router architecture. Some examples of network-based functionality are voice over IP, enhancing QoS support, scaling BGP route reflectors, network-based VPN support, scaling mobile IP support, introducing IPv6 into existing and future networks, and enhancing end-to-end network security. Feature servers remove complexity from routers, allow functions to be implemented on a standard-off-the-shelf server platform, facilitate easy introduction of value-added functions, and scale well.