Recently I had to configure proxy HA for the company that I work for. I started by adding the appliance to the Central Management Config. Then, set the HA config with one of the nodes with a higher director priority, one virtual IP address and I was able to navigate throught that virtual IP address with a DNS record pointing to it. The only problem was that I wasn't getting load balance. I've tried to set the same priority to both appliances, but the requests were only reaching just of the nodes. Also tried to change the priority making the other node the director, but the requests started going to just that node as well.
Doing some research I found this thread https://community.mcafee.com/thread/32255 that stated that a port redirection for the port that use as proxy port must be set in order to achieve HA. So, I did this and the requests magically started to load balance.
As mentioned in the thread, the configuration is not very obvious (tell me about it!) and I want to understand the particular reason for HA to need this setting to work.
Even in documentation I haven't found something very clarifying about this.