Chapter 1: Network Switching Fundamentals

In Depth

Although writing the first paragraph of a book is probably the least important part, it’s invariably the most difficult section to write. To get a good picture of the different parts of networking, readers need to know where networking began and the history behind the networks of today. You may have seen a lot of what is in the first section of this chapter in any basic networking course, such as Networking Essentials; or you may have covered most of it in a CCNA class; but a refresher never hurt.

In this chapter, you will become acquainted with the history of networks and how networks evolved into those you see in today’s corporate environments. I will also discuss the inventors of the different types of networking equipment found at each layer of the network.

As we progress through the chapter I will also cover the different network architectures, from legacy networks to the fast high−speed media types found in today’s networks. A clear understanding of the networking technologies and challenges found at each layer of the network will aid you in assessing problems with the switches you’ll deal with later.

I have a favorite quote that helps me to remember why I continuously study, so that I can better support my customers’ equipment. It is a quote by Albert Einstein, and I remember it from one of my mentors: “The significant [technical] problems we face cannot be solved by the same level of thinking that created them.”

This chapter will contain some of the following information:

∙The history of networking

∙The different pieces of networking equipment

∙How to identify problems in a flat network topology

∙The how to’s and the when to’s of upgrading to a switched network

∙When to upgrade your flat topology network

∙Network upgrade planning and basic strategies

Two terms to keep in mind when reading this chapter are resource nodes and demand nodes. A resource node is a node on an interface attached to a device that provides resources to the network. These nodes can be everything from printers, servers, and mainframes, to wide area network (WAN) routers. A demand node is an interface on the network that makes requests or queries to the resource nodes. The interfaces can be devices such as workstations, terminals, or even client applications. Network conversations occur when resource nodes and demand nodes send a series of requests and responses through the network.

Physical Media and Switching Types

The following are the most popular types of physical media in use today:

∙Ethernet—Based on the Institute of Electrical and Electronics Engineers (IEEE) 802.3 standard. However, it doesn’t rely on the Carrier Sense Multiple Access Collision Detection (CSMA/CD) technology. It includes 10Mbps LANs, as well as Fast Ethernet and Gigabit Ethernet.

∙Token−Ring—Not as popular as Ethernet switching. Token−Ring switching can also be used to improve LAN performance.

∙FDDI—Rarely used, chiefly due to the high expense of Fiber Distributed Data Interface (FDDI) equipment and cabling.

The following are some of the protocol and physical interface switching types in use today:

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