Integrating load balancers into the network

When using the haproxy driver, load balancers are implemented in one-arm mode. In one-arm mode, the load balancer is not in the path of normal traffic to the pool members. The load balancer has a single interface for ingress and egress traffic to and from clients and pool members.

A logical diagram of a load balancer in one-arm mode can be seen in the following diagram:

In the preceding diagram, a load balancer is configured in one-arm mode and resides on the same subnet as the servers it is balancing traffic to.

Because a load balancer in one-arm mode is not the gateway for pool members it is sending traffic to, it must rely on the use of source NAT to ensure that return traffic from the members to the client is sent back through the load balancer. An example of the traffic flow can be seen in the following diagram:

In the preceding diagram, the load balancer receives a request from the client and forwards it to Web1. The load balancer will modify...