Configuring Multiple Instances of OSPF

To configure multiple routing instances of OSPF or OSPFv3, perform the following tasks:

1. Configure the OSPF or OSPFv3 default instance at the [edit protocols (ospf | ospf3)] and [edit logical-systems logical-system-name protocols (ospf | ospf3)] hierarchy levels with the statements needed for your network so that routes are installed in inet.0 and in the forwarding table. Make sure to include the routing table group.
2. Configure an OSPF or OSPFv3 routing instance for each additional OSPF or OSPFv3 routing entity, configuring the following:
   • Interfaces
   • Routing options
   • OSPF protocol statements belonging to that entity
   • Routing table group
3. Configure a routing table group to install routes from the default route table, inet.0, into a routing instance’s route table.
4. Configure a routing table group to install routes from a routing instance into the default route table, inet.0.

   Note: Nonforwarding routing instances do not have forwarding tables that correspond to their routing tables.

5. Create an export policy to export routes with a specific tag and to use that tag to export routes back into the instances. For more information, see the Junos Policy Framework Configuration Guide.

Example: Configuring Multiple Routing Instances of OSPF

Figure 5 shows how you can use multiple routing instances of OSPF or OSPFv3 to segregate prefixes within a large network. The network consists of three administrative entities: voice-policy, other-policy, and the default routing instance. Each entity is composed of several geographically separate sites that are connected by the backbone and managed by the backbone entity.