IS-IS import policy and route prioritization

You can prioritize IS-IS routes that are installed in the routing table for better convergence. In a network with a large number of interior gateway protocol prefixes with BGP Layer 3 VPN or label-based pseudowire service established on top of some interior gateway protocol prefixes, it is important to control the order in which routes get updated in the forwarding table. In previous releases, Junos OS installed IS-IS routes lexicographically in the routing table. You can configure an import policy to prioritize IS-IS routes as per your network requirements. Use a route tag, or filter the routes based on their prefix before setting a priority of high, medium, or low. Use the reject policy option to reject routes from a specific prefix or routes marked with a particular tag. The IS-IS protocol downloads routes to the rpd routing table based on the configured priority. If you do not configure an import policy, all routes are set to a medium priority by default.