Ethernet: The Definitive Guide, 2nd Edition

Chapter 18. Ethernet Switches

Ethernet switches, also known as bridges, are basic building blocks of networks, and are so commonly used that you may not give them a second thought. It’s possible to build networks without knowing very much about how switches work. However, when you build larger network systems, it helps to understand both what goes on inside a switch and how the standards make it possible for switches to work together.

Ethernet is used to build networks from the smallest to the largest, and from the simplest to the most complex. Ethernet connects your home computers and other household devices; switches for home networks are typically small, low-cost, and simple. Ethernet also connects the worldwide Internet, and switches for Internet service providers are large, high-cost, and complex.

Campus and enterprise networks often use a mix of switches, with simpler and lower-cost switches used inside wiring closets to connect devices on a given floor of a building, and larger and higher-cost switches in the core of the network to connect all the building switches together into a larger network system. Data center networks have their own special requirements, and typically include high-performance switches that can be connected in ways that provide highly resilient networks.

According to industry estimates, the worldwide market for enterprise switches had revenues of over $5 billion per quarter in 2013, with total revenues exceeding $20 billion for the year. For the third ...