Route Targets
Sometimes, customer sites need to participate in more than one MPLS VPN.
Export and import route targets (RT) are attributes attached to BGP routes to
indicate which VPNs the route belongs to. This allows the creation of
complex topologies with overlapping VPNs:
■ Export RT—Attached to routes when they are imported into the VRF
database to identify the VPNs to which the route belongs. These routes
are then advertised to other PE routers.
■ Import RT—Used by the PE router receiving the routes to identify
which VRFs should receive the routes. VRFs with an import RT
matching the route’s RT will import the route. These networks are then
installed in the VRF table and advertised to the appropriate customer
routers.