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Introduction

Have you ever listened or sat in on a concept or network design meeting and been fed an alphabet soup of acronyms and words or technical jargon that just didn't make sense to you? Well, the chances are that Ethernet, Token Ring, FDDI, and Wireless were among some of those being spoken.

In this writing, the author plans to help one understand, in simple terms (where possible), what exactly these technologies are and where they may belong. He provides an overview of each, explains the differences between them, and outlines the advantages and disadvantages of using them. His goal is to provide you, the reader, with the ability to understand at a high-level what these technologies are, and how they can be used.

What are Ethernet, Token Ring, FDDI, and Wireless?

They are all Local Area Network (LAN) technologies or standards for communication across different medium. In the past decades the essence of internetworking has vastly increased. As always, demand breeds supply, and several different LAN technologies have emerged. LANs can be implemented in several ways. They can be divided into several subgroups based on e.g. physical implementation or standardized technologies. Choosing the right kind of LAN solution for a particular purpose always depends on several issues, e.g. size of the network, location of the terminals, and cost. Let us look a little deeper in the details.

Ethernet

Ethernet is the most widely used local area network (LAN) technology. The original and most popular version of Ethernet supports a data transmission rate of 10 Mb/s. Newer versions of Ethernet called "Fast Ethernet" and "Gigabit Ethernet" support data rates of 100 Mb/s and 1 Gb/s (1000 Mb/s). An Ethernet LAN may use coaxial cable, special grades of twisted pair wiring, or fiber optic cable. "Bus" and "Star" wiring topologies are supported. Ethernet devices compete for access to the network using a protocol called Carrier Sense Multiple Access with Collision Detection (CSMA/CD).

Token Ring & Fiber Distributed Data Interface (FDDI)

Ethernet CSMA/CD networks provide a relatively simple way of passing data. However, many industry observers correctly note that CSMA/CD breaks down under the pressure exerted by many computers on a network segment. These observers are correct; the constant contention for bandwidth that is part and parcel of Ethernet does not always scale efficiently.

In an attempt to circumvent this problem, IBM and the IEEE created another networking standard called 802.5. IEEE 802.5 is more commonly identified with token ring; FDDI also uses the 802.5 method of moving data around networks.

Token ring works very differently from Ethernet. In Ethernet, any computer on a given network segment can transmit until it senses a collision with another computer. In token ring and FDDI networks, by contrast, a single special packet called a token is generated when the network starts up and is passed around the network. When a computer has data to transmit, it waits until the token is available. The computer then takes control of the token and transmits a data packet. When it is done, it releases the token to the network, and the next computer grabs the token if it has data to transmit

In comparison to the contentious nature of Ethernet; token ring and FDDI appear quite civilized. These two logical topologies do not have collisions in which multiple stations try to send data; instead, every computer waits its turn.

Although similar to Token Ring; FDDI uses dual-ring architecture