Generic ISP BGP prefix filter
This prefix-list MUST be applied to all external BGP peerings, in and out!
ip prefix-list rfc1918-sua deny 0.0.0.0/8 le 32
ip prefix-list rfc1918-sua deny 10.0.0.0/8 le 32
ip prefix-list rfc1918-sua deny 127.0.0.0/8 le 32
ip prefix-list rfc1918-sua deny 169.254.0.0/16 le 32
ip prefix-list rfc1918-sua deny 172.16.0.0/12 le 32
ip prefix-list rfc1918-sua deny 192.0.2.0/24 le 32
ip prefix-list rfc1918-sua deny 192.168.0.0/16 le 32
ip prefix-list rfc1918-sua deny 224.0.0.0/3 le 32
ip prefix-list rfc1918-sua deny 0.0.0.0/0 ge 25
ip prefix-list rfc1918-sua permit 0.0.0.0/0 le 32