Multi-protocol BGP Extension
BGP is originally designed to carry routing information for IPv4 address families only. Since VPN-IPv4 addresses are 12 bytes wide, BGP requires some kind of extension to carry VPN-V4 address family routing information. This is achieved by using MBGP extension which allows BGP to carry multiprotocol address families routing information. Therefore, to deploy BGP/MPLS VPNs and to support the distribution of VPN-IPv4 routes, PE routers are required to support the MP-BGP extensions with VPN-IPv4 address family support.