[SLB] Server Load Balancing with DSR

IPVS ( based on LVS) provides 3 kind of ways to do server load balancing:

1. Virtual Server via Network Address Translation（VS/NAT）
2. Virtual Server via IP Tunneling（VS/TUN）
3. Virtual Server via Direct Routing（VS/DR） 

Recently I find another way to do load balancing, and it is Direct Server Return
http://techiess.wordpress.com/2010/09/09/load-balancing-dsr-direct-server-return/
Using DSR, packet is returning directly from the server to client without going through L4 switch.