Routing Policy Features in the Junos OS

The Junos OS provides a routing policy language that enables you to control the transfer of routing information between the routing protocols and the routing tables, and between the routing tables and the forwarding table.

You can configure policies that examine characteristics of incoming and outgoing routes, including the following:

• Address family
• Aggregate route contributors
• BGP AS path, AS path group, community, and origin attributes
• Destination prefix
• IP address or list of addresses
• IS-IS level
• Metric
• Multicast source address
• Neighbor (peer)
• Next-hop address
• OSPF area identifier
• OSPF external route and tags
• Preference
• Protocol from which route was learned
• Router interface
• Routing instance
• Routing table

You can configure policies to perform certain actions when routes match specified characteristics, including the following actions:

• Accept the routes
• Add, delete, or set the BGP community
• Add or delete a BGP local preference
• Apply BGP route-damping parameters
• Apply CoS parameters
• Choose a next hop to install into the forwarding table
• Create a forwarding class
• Evaluate the next term in the policy
• Evaluate the next policy in a policy chain
• Extract the last AS number from an AS path
• Maintain packet counts based on source and destination address
• Modify the metric value
• Modify the preference value
• Perform per-packet load balancing
• Prepend an AS path
• Reject the routes
• Set the BGP MED and origin attribute
• Set the external metric type
• Set the next hop
• Specify or modify OSPF tags