Other PEs that the user wants to exchange IBGP routes with must be configured as BGP neighbors. In addition, the neighbor must be set to enable the BGP to update the loopback address. To assign an IBGP neighbor with the IP address 10.33.35.1, a remote AS number of 1, and an update-source to loopback 1 of the PE 1 router shown in IBGP example, enter the following commands.
device(config-bgp)# neighbor 10.2.2.2 remote-as 1
device(config-bgp)# neighbor 10.2.2.2 update-source loopback 1
device(config-bgp)# address-family vpnv4 unicast
device(config-bgp-vpnv4u)# neighbor 10.2.2.2 activate