Secure Network Components
In Chapter 10, we saw how the OSI and TCP/IP models can be used to break down IT architecture into different layers. The first of these layers is the physical layer—essentially, the equipment, transmission media, and endpoints that connect to a network. Before you examine the ways in which different network components can be secured, it is crucial to understand high availability (HA) and fault tolerance. As we covered in Chapter 1, availability is one of the five core security concepts. HA and fault tolerance are how you provide availability in your networks.
A fault-tolerant environment has zero service interruption but comes at a much higher cost, whereas a highly available environment has tolerance for minor service interruptions and is cheaper to set up. At their core, these two concepts have the same objective (to provide the required level of availability). The only difference between them is the cost associated with achieving that objective...
