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Figure 103: Global Import Map Applied to Routes Imported from VRF BGP RIB
The global import map enables global BGP routes to be automatically imported into
the BGP RIB table in a VRF. The route map determines which routes are imported
and which are not. When they are installed in the VRF routing table, the imported
routes point to IP interfaces in the parent virtual router.
To configure a route map and global import map for importing specific routes.
host1(config)# virtual-router pe1
host1:pe1(config)# prefix-list internet-host permit 10.5.5.5/32
host1:pe1(config)# route-map globimap1
host1:pe1(config-route-map)# match ip address prefix-list internethost
host1:pe1(config-route-map)# exit
host1:pe1(config)# ip vrf pe11
host1:pe1(config-vrf)# rd 100:1
host1:pe1(config-vrf)# route-target both 100:1
host1:pe1(config-vrf)# global import map globimap1
Creating a BGP Session Between the CE Router and the Parent VR
The fallback global option enables traffic that arrives at a VRF from the CE router to
be sent out on the uplink determined to be optimal by using the full Internet routing
table present in the parent VR.
If a CE router is multihomed to multiple PE routers, it must receive a full Internet
routing table from each of the PE routers so that the CE router can determine which
of the PE routers is optimal for a given Internet prefix.
You can easily create a BGP session from the VRF to the CE router to advertise routes
in the VRF to the CE router. However, doing this is insufficient because the VRF does
not contain the full Internet routing table, which is present only in the parent VR.
This situation requires a BGP session from the parent VR to the CE router (Figure
104 on page 460). This BGP session in turn requires a route in the VRF to the loopback
Providing Internet Access to and from VPNs
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Chapter 5: Configuring BGP-MPLS Applications