A network router dynamically reconfigures representations of forwarding structures used within a forwarding unit of the router. The forwarding structures comprise a plurality of forwarding next hops associated with the routes and stored in a first representation within the forwarding unit. The router further comprises a control unit having a processor to install the forwarding structures within the forwarding unit. In response to input directing the router to change from a first operating mode to a second operating mode, the control unit installs, within the forwarding unit, one or more new forwarding next hops that are associated with none of the routes by the forwarding structures and are stored in a second representation within the forwarding unit that is different from the first representation and, after installing the new forwarding next hop, updates the forwarding structures to associate at least one of the routes to the new forwarding next hop.