• Each vrf on the PE router must have on RD.
• RD format:
• ASN:NN
• If customer(VPN) connected to different PE routers then 2 separate RDs must be used.

• VPN prefixes are propagate across the MPLS VPN network my MP-BGP.
• RDs used to these VPN prefixes make unique.
• A prefix derived from the combination of the IPv4 prefix & the RD is calld VPNv4 prefix.
• MP-BGP will carry the these VPNv4 prefixes between the PE routers

• In cisco ios, cef is the only switching method supported for forwarding ip packets from the VRF interface.
• So CEF must be enabled globally on all PE routers & all VRF interfaces
• 
  

• Routing should be separate & private for each customer(VPN) on a PE router.
• so each vpn has its own routing table.
• Thi private routing table is called VRF routing table.
• 
  

• VRF is combination of
• VPN routing table
• VRF CEF table
• ip routing protocols
• For every VPN attached to the PE, there is one VRF