Juniper JUNOSE 11.2.X BGP AND MPLS, Руководство по настройке

Страница: 501 / 742

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 466). This BGP session in turn requires a route in the VRF to the loopback interface
465 Copyright © 2010, Juniper Networks, Inc.
Chapter 6: Configuring BGP-MPLS Applications