Example: Configuring PE-to-CE BGP Sessions

If you have established a BGP session between a PE and a particular CE router, you can configure BGP sessions with all the other customer sites within the VPN so that they can learn the routes to the particular CE router.

Configuring the PE-to-CE external BGP session is a bit different from the usual external BGP session. You must configure the session in the context of the IPV4 unicast address family of the VRF. Consider the topology shown in Figure 96.

Figure 96: PE-to-CE Session

PE-to-CE Session

You configure the characteristics of VRF A, the global BGP attributes, the address family for the session, and BGP attributes relevant to the VRF or address family.

host1(config)#ip vrf vrfa host1(config-vrf)#rd 777:5 host1(config-vrf)#route-target both 777:5 host1(config-vrf)#exit host1(config)#interface gigabitEthernet 1/0 host1(config-if)#ip vrf forwarding vrfA host1(config-if)#ip address host1(config-if)#exit host1(config)#router bgp 777
(Not shown: Configuration of other global BGP attributes)host1(config-router)#address-family ipv4 unicast vrf vrfA host1(config-router-af)#neighbor remote-as 73
(Not shown: Configuration of BGP attributes relevant to the VRF or the address family)

See Configuring BGP Routing, for more information about configuring BGP.

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