Home > Articles > Networking > Wireless/High Speed/Optical

A View of the LANscape

Network expert Bill Stallings provides an overview of the types of local area networks (LANs) that dominate the market, in this second in a series of articles on LANs.
From the author of

An essential element of any organization's data-processing operation is a local area network (LAN). A LAN is needed to interconnect equipment on the user's premises and to provide a means to efficiently connect to outside services and other corporate sites. Over the years, a wide variety of technologies and configurations have been turned into products, making life difficult for managers and network administrators. Fortunately, in recent years, a small group of LAN approaches have come to dominate the market, making life much easier for those who have to select and maintain LANs. In this article, we look at the key product types on the LAN scene today:

  • Ethernet

  • Fibre Channel

  • IEEE 802.11 Wireless LAN


The most widely used LANs today are based on Ethernet, a scheme that has been around for about 25 years. An experimental, 3 Mbps version was developed in the mid-1970s by Xerox. Then, in 1980, Xerox, Intel, and Digital Equipment Corporation jointly issued a specification for a 10 Mbps Ethernet system and freely licensed the technology. Thus, the commercial version of Ethernet was born, and it quickly came to dominate the marketplace. By the mid-1980s, a standard for Ethernet was issued by the IEEE 802.3 working group. As explained in another article in this series, the IEEE 802 committee was set up to develop a range of standards for LANs; the 802.3 standard differs in minor ways from the Xerox specification, but is also referred to as Ethernet. The 802.3 working group quickly became—and remains—the most important part of the IEEE 802 effort.

Classical Ethernet

The original commercial Ethernet operates over a bus topology LAN using coaxial cable. In a bus topology LAN, all stations attach, through appropriate hardware interfacing known as a tap, directly to a linear transmission medium, or bus. Full-duplex operation between the station and the tap allows data to be transmitted onto the bus and received from the bus. A transmission from any station propagates the length of the medium in both directions and can be received by all other stations. At each end of the bus is a terminator, which absorbs any signal, removing it from the bus.

Moving to Higher Speeds

Although Ethernet quickly became the dominant force in the marketplace, because of its simplicity and robustness, the shortcomings of a 10 Mbps capacity became apparent. Personal computers and microcomputer workstations began to achieve widespread acceptance in business computing in the early 1980s and have now achieved virtually the status of the telephone: an essential tool for office workers. Until relatively recently, office LANs provided basic connectivity services—connecting personal computers and terminals to mainframes and midrange systems that ran corporate applications, and providing workgroup connectivity at the departmental or divisional level. In both cases, traffic patterns were relatively light, with an emphasis on file transfer and electronic mail. The LANs that were available for this type of workload, primarily Ethernet and token ring, are well suited to this environment.

In recent years, two significant trends have altered the role of the personal computer and therefore the requirements on the LAN:

  • The speed and computing power of personal computers has continued to enjoy explosive growth. Today's more powerful platforms support graphics-intensive applications and ever more elaborate graphical user interfaces for the operating system.

  • MIS organizations have recognized the LAN as a viable and indeed essential computing platform, resulting in the focus on network computing. This trend began with client/server computing, which has become a dominant architecture in the business environment and the more recent intranetwork trend. Both of these approaches involve the frequent transfer of potentially large volumes of data in a transaction-oriented environment.

The effect of these trends has been to increase the volume of data to be handled over LANs and, because applications are more interactive, to reduce the acceptable delay on data transfers. The earlier generation of 10 Mbps Ethernets and 16 Mbps token rings are simply not up to the job of supporting these requirements.

The following are examples of requirements that call for higher-speed LANs:

  • Centralized server farms. In many applications, there is a need for user or client systems to be able to draw huge amounts of data from multiple centralized servers, called server farms. An example is a color publishing operation, in which servers typically contain tens of gigabytes of image data that must be downloaded to imaging workstations. As the performance of the servers themselves has increased, the bottleneck has shifted to the network. Switched Ethernet alone would not solve this problem because of the limit of 10 Mbps on a single link to the client.

  • Power workgroups. These groups typically consist of a small number of cooperating users who need to draw massive data files across the network. Examples are a software development group that runs tests on a new software version, or a computer-aided design (CAD) company that regularly runs simulations of new designs. In such cases, large amounts of data are distributed to several workstations, processed, and updated at very high speed for multiple iterations.

  • High-speed local backbones. As processing demand grows, LANs proliferate at a site, and high-speed interconnection is necessary.

Ethernet Meets the Challenge

In response to the need for greater speed, in the mid-1990s the IEEE 802.3 committee introduced a 100 Mbps version known as Fast Ethernet. Unlike the traditional bus arrangement of classical Ethernet, Fast Ethernet uses a hub or switch to achieve greater performance.

To clarify the distinction between buses, hubs, and switches, Figure 1a shows a typical bus layout of a traditional 10 Mbps Ethernet. In this configuration, all the stations must share the total capacity of the bus, which is 10 Mbps.

Figure 1a

Bus layout.

In a hub, there is a central point to which wires are strung from individual stations on the LAN. In this arrangement, a transmission from any one station is received by the hub and retransmitted on all of the outgoing lines. Again, the total capacity of the LAN is the same as that of the access lines from each station, namely 10 Mbps. The hub has several advantages over the simple bus arrangement. It exploits standard building wiring practices in the layout of cable. In addition, the hub can be configured to recognize a malfunctioning station that's jamming the network, and to cut that station out of the network. Figure 1b illustrates the operation of a shared-medium hub. Here again, station B is transmitting. This transmission goes from B across the transmit line from B to the hub, and from the hub along the receive lines of each of the other attached stations.

Figure 1b

Hub layout.

We can achieve greater performance with a LAN switch. In this case, the central element acts as a switch, similar to a packet switch. An incoming frame from a particular station is switched to the appropriate output line to be delivered to the intended destination. At the same time, other unused lines can be used for switching other traffic. Figure 1c shows an example in which B is transmitting a frame to A and at the same time C is transmitting a frame to D. In this example, the current throughput on the LAN is 20 Mbps, although each individual device is limited to 10 Mbps.

Figure 1c

Switch layout.

The LAN switch has several attractive features:

  • No change is required to the software or hardware of the attached devices to convert a bus LAN or a hub LAN to a switched LAN. In the case of an Ethernet LAN, each attached device continues to use the Ethernet medium access-control protocol to access the LAN. From the point of view of the attached devices, nothing has changed in the access logic.

  • Each attached device has a dedicated capacity equal to that of the entire original LAN, assuming that the layer 2 switch has sufficient capacity to keep up with all attached devices. For example, in Figure 1c, if the layer 2 switch can sustain a throughput of 20 Mbps, each attached device appears to have a dedicated capacity for either input or output of 10 Mbps.

  • The layer 2 switch scales easily. Additional devices can be attached to the layer 2 switch by increasing the capacity of the layer 2 switch correspondingly.

Using the switch technology, the IEEE 802.3 committee has now gone on to introduce 1 Gbps Ethernet LANs and is working on 10 Gbps LANs. All of these options are discussed in another article in this series.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020