16.1 Network Infrastructure Concepts
16.1.3 LAN architecture elements
There are three primary LAN network architectures or technologies that are used today: Ethernet, Token Ring, and FDDI (Fiber Distributed Data Interface). Of these, Ethernet is by far the most common. It is estimated that over 90% of installed networks are some form of Ethernet. The Institute of Electronic and Electrical Engineers (IEEE) 802.3 committee developed the current standards on Ethernet. IEEE 802.5 committee developed standards for Token Ring, and The American National Standards Associations (ANSI) is responsible for FDDI standards. The LAN architecture is relatively independent of the network operating system. As a result, most network operating systems, including Windows NT/2000, Novell NetWare, and UNIX can utilize various underlying architectures.

All LAN (and WAN) architectures or technologies are comprised of 5 major design elements. When building a network you must consider all of these factors. For instance, if you are designing an Ethernet network, you must acquire Ethernet components and follow the requirements and specifications of the Ethernet standards. Major design elements include:

Topologies Supported - Topology is the layout or arrangement of network components. Some architectures support more than one topology. Examples of topologies include: Bus, Star, Ring and Mesh. These topologies will be discussed later in the chapter.

Cabling Specifications - These specifications include cable types, connectors, patch panels, wall plates, electrical/optical characteristics, and maximum distances allowed.

Network Interface Card (NIC) Design - Electrical characteristics, connectors, transmit and receive electronics, physical hardware addressing.

Interconnecting Devices - These are concentration or aggregation devices and usually include hubs, switches, multi-station access units and routers.

Access Method - Technique used to allow multiple users to share the network.

Due to its prevalence, this chapter will focus on Ethernet and its current implementations. The Figure summarizes the major design elements that make up a network architecture.