Routing Policies, Firewall Filters, and Traffic Policers User Guide
Routing policies allow you to control the routing information between the routing protocols and the routing tables and between the routing tables and the forwarding table. All routing protocols use the Junos OS routing tables to store the routes that they learn and to determine which routes they should advertise in their protocol packets. Routing policies also allow you to control which routes the routing protocols store in and retrieve from the routing table.
Firewall filter policies allow you to control packets transiting the router to a network destination and packets destined for and sent by the router. They provide a means of protecting your router from excessive traffic transiting the router to a network destination or destined for the Routing Engine. Firewall filters that control local packets can also protect your router from external incidents such as denial-of-service attacks.