LVS/DR

It stands for Linux Virtual Server via Direct Routing, an IP load balancing technology implemented in LVS. It directly routes packets to backend server through rewriting MAC address of data frame with the MAC address of the selected backend server. It has the best scalability among all other methods because the overhead of rewriting MAC address is pretty low, but it requires that the load balancer and the backend servers are in a physical network.

See more information about Linux Virtual Server via Direct Routing at http://www.linuxvirtualserver.org/VS-DRouting.html