With the fundamentals of networking under our belt, we can now take a closer look at the infrastructure
that makes up the networks we all use. This section focuses on the switches and routers that make up networks,
along with the protocols that drive them.
We start this section with a discussion of the Ethernet protocol, which defines the rules and processes by
which computers in a local area communicate. Long before the Internet was in use, computers communicated
locally using the Ethernet protocol, and it is still widely used.
We then move on to local-area network (LAN) switching, an extension of the Ethernet protocol required
when there are more computers in a local segment than can communicate efficiently. Switching is one of
the core technologies in networking.
One of the necessities in networking is link redundancy, something that makes it more likely that data
reaches its intended target. Sometimes, however, link redundancy can create loops in the network, which
causes an explosion of administrative traffic that can take down a network in a matter of minutes.
Spanning Tree is one of the mechanisms that keeps these “broadcast storms” from wiping out your local
network, so we look at how this important protocol works.
We end this section with routing, which provides the basis for network communication over long distances.
The advent of routing allowed the growth of the Internet and corporate networking as we know it
today. This section explores how routing works and how routers communicate.