Types of redundancy and load balancing
Before we delve into specific high-availability features and their configuration, let’s discuss possible types of redundancy and load balancing, their advantages, and their limitations.
First of all, we need to remember that the modern TCP/IP networking stack is layered. Multiple layering models include different numbers of layers but the idea is the same: protocols at the upper layer are unaware of the protocols at any lower levels and vice versa. The most commonly used models are the seven-layer Open Systems Interconnection (OSI) model and the four-level DoD model (developed by the United States Department of Defense). We have summarized them in the following table:
OSI model |
DoD model |
Purpose |
Examples |
Physical |
Link |
Transmission of electrical... |