Routers in the Internet core exchange between three and six million routing prefixes each day, and the fluctuation of network topology can have a direct impact on a router’s performance. A router that has not yet reached convergence in its internal routing tables may drop packets or deliver packets to the wrong next-hop router. Topology changes in the Internet must be reflected in both the routing and forwarding tables within routers. The router architecture illustrated in Figure 1 indicates that the routing table and the forwarding table are likely to be implemented in separate hardware modules within routers. In fact, in modern carrier-class routers, the forwarding table is often duplicated on each line card. The operations by which changes propagate from the routing table to the forwarding tables are potentially complex, and certainly very time-critical. These databases must remain closely synchronized or routing loops and packet loss are likely.