The TX Matrix Routing Engine constructs and maintains one or more routing tables. From the routing tables, the Routing Engine derives a table of active routes, called the forwarding table, which is then copied to the T1600 routers. The JUNOS kernel running on each T1600 Routing Engine copies its forwarding table to all Packet Forwarding Engines in the router. The design of the ASICs allows the forwarding table in the Packet Forwarding Engine to be updated without interrupting forwarding performance.