# CE–PE Behavior Overview

CE 1 is connected to VRF A in PE 1 through an IPv4 interface. Similarly, CE 2 is connected to VRF B in PE 2 through an IPv4 interface. You can alternatively run OSPF to the CE devices over IPv6 links and redistribute the OSPF IPv6 routes into BGP.

The MP-BGP sessions between the CE devices and the VRFs in the PE routers are established over TCPv4. The AFI value is 2, indicating IPv6; the SAFI value is 1, indicating unicast. CE 1 advertises IPv6 network 6001:0430::/48 to its MP-BGP peer in VRF A. CE 2 advertises 6001:0431::/48 to its MP-BGP peer in VRF B. When it receives the advertised prefix in VRF A, BGP adds 6001:0430::/48 to its BGP VPNv6 RIB with the stacked label L1, which MPLS allocated for this prefix. The default IPv6 VRF label is L1.