Today, with new services and applications blooming on the internet, to enable traditional routers to offer enough capability and speed of upgrade along with these services and applications in time would become even harder than ever. Run-time reconfiguration (RTR), based on the Field Programmable Gate Array (FPGA), is a new promising technology that can configure the partial or total hardware logic resources of a system at run time. Based on the technology, reconfigurable routers can support dynamic reconfiguration of new hardware logic for the new service, while keeping the other services still run properly, hence can provide a new possible solution to the update problem of the traditional routers. After introducing the basic concepts of RTR and the current development of the FPGA, this paper summarizes the past major research efforts with respect to the reconfigurable router, as well as the current work on it. Research directions and open problems are also discussed from the point of view of reconfigurable network.