UDP service binding issue in LVS/DR and LVS/TUN
From LVSKB
Problem
If real servers run UDP service binding with any address (0.0.0.0), the problem is that response packet will use the ip address of real server as source address, instead of the VIP address, and then it will break the service, because the client sends requests to the VIP address and expects responses from the VIP address too.
Solution
The quick solution is to get UDP service bind with the VIP address.