Chapter 7: Routing Policy Configuration Guide110 SmartSwitch Router User Reference ManualIt is only possible to restrict the importation of OSPF ASE routes when functioning as anAS border router.Like the other interior protocols, preference cannot be used to choose between OSPF ASEroutes. That is done by the OSPF costs.Route-FilterThis component specifies the individual routes which are to be imported or restricted. Thepreference to be associated with these routes can also be explicitly specified using thiscomponent.The preference associated with the imported routes are inherited unless explicitlyspecified. If there is no preference specified with a route-filter, then the preference isinherited from the one specified with the import-source.Every protocol (RIP, OSPF, and BGP) has a configurable parameter that specifies default-preference associated with routes imported to that protocol. If a preference is not explicitlyspecified with the route-filter, as well as the import-source, then it is inherited from thedefault-preference associated with the protocol for which the routes are being imported.Export PoliciesExport policies control the redistribution of routes to other systems. They determinewhich routes are advertised by the Unicast Routing Process to other systems. Every exportpolicy can have up to three components:• Export-Destination• Export-Source• Route-FilterExport-DestinationThis component specifies the destination where the routes are to be exported. It alsospecifies the attributes associated with the exported routes. The interface, gateway or theautonomous system to which the routes are to be redistributed are a few examples ofexport-destinations. The metric, type, tag, and AS-Path are a few examples of attributesassociated with the exported routes.Export-SourceThis component specifies the source of the exported routes. It can also specify the metricto be associated with the routes exported from this source.
