3.10. Why netmask=/32 for the VIP in LVS-DR?
Horms 29 Oct 2003
If you are using LVS-DR then the packets that arrive on the real servers have
the destination IP address set to the VIP. So the real servers need some way of
accepting this traffic as local. One way is to add an interface on the loopback
device and hide it so it won’t answer ARP requests.
The netmask has to be 255.255.255.255 because the loopback interface will
answer packets for all hosts on any configured interface. So 192.168.1.110
with netmask of 255.255.255.0 will cause the machine to accept packets for all
addresses in the range 192.168.1.0 - 192.168.1.255, which is probably not what