Networks were initially designed to create internal segments that were separated from the external world by using a fixed perimeter. The internal network was deemed trustworthy, whereas the external was considered hostile. However, this is still the foundation for most networking professionals even though a lot has changed since the inception of the design.
More often than not the fixed perimeter consists of a number of network and security appliances, thereby creating a service chained stack, resulting in appliance sprawl. Typically, the appliances that a user may need to pass to get to the internal LAN may vary.
