test client -> firewall -> lvs server -> realserver
2.2.2.200 -> 2.2.2.6(VIP's public ip) -> 192.168.5.20(VIP) -> 192.168.5.33
firewall nat: 2.2.2.6-> 192.168.5.20
only one real server
lvs:
1.DR mode
2.through arptables implement lvs to realserver distribution
3. realserver's arptables: