A、The virtual routing and forwarding table is separate from the global routing table that exists on PE routers. Routes are injected into the VRF from the CE-PE routing protocols for that VRF and any MP-BGP announcements that match the defined VRF RTs

B、Multiprotocol Border Gateway Protocol is run between PE and CE routers to exchange customer prefixes in a VPNv4 format

C、A customer edge router peers at Layer 3 to the provider edge. The PE-CE interface runs either a dynamic routing protocol （eBGP， RIPv2， EIGRP， OSPF） or a static routing protocol （Static， Connected）

D、VPNv4 address is the combination of the RT and customer IPv4 prefix. These VPNv4 prefixes are passed in MP-BGP