| 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.
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