This article is a guide to setting up redundant firewalls using Red Hat Enterprise Linux 7, that services high-availability and load-balancing requirements for the firewalls themselves as well as the services in networks behind it.
The base architecture of the network consists of at least 1 subnet on the outside of the firewalls, facing the Internet, and multiple subnets on the inside. The internal networks are supposed to use private IP space. This article does not concern itself with additional DMZ considerations, nor specific Internet connectivity or customer edge router requirements, nor hypervisor network configuration and provisioning techniques.