Juniper JUNOSE, Configuration Manual

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Table 62: Characteristics of Export and Global Export Maps (continued)
Global Export Export Characteristic
Yes Yes Exports both best and non-best routes. The best route selection is
made again in the core after the export.
Subsequent Distribution of Routes
Routes that are imported from the global BGP non-VPN RIB (with a global import
map) into a VRF RIB are never exported again. Because these routes are not exported
to the global VPN RIB, they are not advertised to other PE routers. These imported
routes are never exported to the VRF RIBs of overlapping VPNs.
Routes that are exported from a VRF RIB to the global BGP non-VPN RIB with the
global export map are never imported back in to any VRF.
Routes that are imported from the global BGP VPN RIB (with an import map) into a
VRF RIB are never exported again.
Routes that are exported from a VRF RIB to the global VPN RIB can be imported into
the RIB of other VRFs. This behavior might be seen with overlapping VPNs.
Creating a Map
For information about creating a route map to be used as an import or export map,
see “Configuring BGP Routing” on page 3. The following example shows how to
apply the route map
routemap5 to the VRF vpnA configured on the virtual router
boston .
host1(config)# virtual router boston
host1:boston(config)# ip vrf vpnA
host1:boston(config-vrf)# import map routemap5
Export Maps
You can use an export map to change the attributes of a route when it is exported
from a VRF to the global BGP VPN RIB local to the VR. This RIB is often referred to
as the core VPN RIB. Export maps can optionally filter routes.
When the VRF route matches the export map, the route is exported and the attributes
are changed as specified in the export map.
When the VRF route does not match the export map, the filter keyword determines
what happens. If the filter keyword has been issued, then the route is not exported.
If the filter keyword has not been issued, then the route is exported but the attributes
of the route are not modified (because the export map was not matched).
If you do not configure an export map, then all routes are exported from the VRF to
the global BGP VPN RIB. However, routes that are imported into the VRF cannot be
exported again.
Configuring BGP VPN Services
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Chapter 5: Configuring BGP-MPLS Applications