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Simplified Interinstance Configuration

 

By changing the configuration format of interinstance export policies, Junos OS Release 5.4 and later makes it easier to share routes between VRF instances, other types of instances (such as nonforwarding instances), and IGPs.

VRF instances can share routes with the auto-export statement. When you configure auto-export, the vrf-import and vrf-export policies are compared across all VRF instances. If there is a common route target community between the instances, the routes are shared.

For VRF instances, such as overlapping VPNs, the basic hierarchy levels for auto-export are as follows:

For nonforwarding instances, routes are imported into the instance so routing protocols can announce them. For more information, see Configuring Nonforwarding Instances.

A third option for interinstance export is using an interior gateway protocol (IGP), such as Open Shortest Path First (OSPF) or Intermediate System-to-Intermediate System (IS-IS). An example of the hierarchy used for IGP import and export is listed below.

When configuring interinstance route sharing, keep this information in mind:

  • The instance-import and instance-export commands cannot be used with VRF instances. They are equivalent to the vrf-import and vrf-export VRF-specific commands.

  • Traceoptions in the master instance apply to the routing table export task. Consequently, such traceoptions are propagated to all other instances, although they can be modified as needed.

  • The auto-export statement applies to VRF and non-VRF instances.

  • Use of the command instance-import automatically enables auto-export for non-VRF instances.

  • Some network administrators use the instance-import functionality to create communities of interest. By setting up different VPNs and sharing routes between instances as needed, administrators can tailor services to the needs of their customers. For an example, see Configuring Nonforwarding Instances.

To save time when configuring interinstance parameters on multiple instances, you can configure the auto-export command to be the default behavior for all your routing instances by means of a configuration group.

At the desired hierarchy level, you apply the configuration group, and all members of the group receive the same policy: