JUNOS Routing Tables

The JUNOS software routing table is used by the routing protocol process to maintain its database of routing information. In this table, the routing protocol process stores statically configured routes, directly connected interfaces (also called direct routes or interface routes), and all routing information learned from all routing protocols. The routing protocol process uses this collected routing information to select the active route to each destination, which is the route that actually is used to forward packets to that destination.

By default, the JUNOS software maintains three routing tables: one for unicast routes, another for multicast routes, and a third for Multiprotocol Label Switching (MPLS). You can configure additional routing tables to support situations where you need to separate a particular group of routes or where you need greater flexibility in manipulating routing information. In general, most operations can be performed without resorting to the complexity of additional routing tables. However, creating additional routing tables has several specific uses, including importing interface routes into more than one routing table, applying different routing policies when exporting the same route to different peers, and providing greater flexibility with incongruent multicast topologies.

Each routing table is identified by a name, which consists of the protocol family followed by a period and a small, nonnegative integer. The protocol family can be inet (Internet), iso (ISO), or mpls (MPLS). The following names are reserved for the default routing tables maintained by the JUNOS software:

• inet.0—Default Internet Protocol version 4 (IPv4) unicast routing table
• inet6.0—Default Internet Protocol version 6 (IPv6) unicast routing table
• instance-name.inet.0—Unicast routing table for a particular routing instance
• inet.1—Multicast forwarding cache
• inet.2—Unicast routes used for multicast reverse path forwarding (RPF) lookup
• inet.3—MPLS routing table for path information
• mpls.0—MPLS routing table for label-switched path (LSP) next hops  

  Note: For clarity, this manual contains general discussions of routing tables as if there were only one table. However, when it is necessary to distinguish among the routing tables, their names are explicitly used.

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