I have many environments that use hardware load balancers. This can be very costly sending a lot of traffic through a load balancer. So we are starting to move to a DSR load balance design. A DSR load balance design is when a request comes into the load balancer the reply doesn’t go back through the load balancer, this keeps traffic through the load balancer at a minimal. When you set up your network load balancer you have to pass the return ip to do this you need to set up a loop-back ip. once that is setup you use a loop-back ip on the server that will act as the load balancer to return to original source with out going back through the load balancer.

DSR Load Balance

To set up Loop-back
Create a second lo file Make sure there is no ARP

cp /etc/sysconfig/network-scripts/ifcfg-lo /etc/sysconfig/network-scripts/ifcfg-lo:0
vi /etc/sysconfig/network-scripts/ifcfg-lo:0

DEVICE=lo:0
IPADDR=1
#### Make sure you use nor arp
ARP=no
NETMASK=255.255.255.255
# If you're having problems with gated making 127.0.0.0/8 a martian,
# you can change this to something else (255.255.255.255, for example)
ONBOOT=yes

Now bring up your loop-back

 /sbin/ifup lo:0