ANF Assigned Number Field
                In MPLS and other VPN based networks VPN-IPv4 is used to ensure addressing spaces within the VPN do not cross. The VPN-IPv4 address is defined through the RD. The RD comprises of the AF (Administrator Field) and the ANF. The ANF defines the VPN-IPv4 variable and is populated by the service provider. 
            
            
         
                
             
                
             
                
             
             
             
             
             
             
            