NETWORKING

Computer networks consist of multiple computers and
other electrical devices linked together. Networks are classified
as local area networks (LANs) or wide area networks
(WANs). The difference between LANs and WANs is
usually determined by the length of the network. Generally,
a LAN’s distance includes only several hundred yards.
LANs reside mostly in offices, work areas, classrooms, one
building, or within several buildings. WANs exist over
many miles, across several cities, and even around the
world. WANs are multifaceted and complex networks.
They require many devices that connect different computers
using diverse communication services. WAN communication
speed, reliability, and connectivity are more
challenging to manage than those of a LAN.
HISTORICAL ACHIEVEMENTS IN
COMMUNICATION AND
TRANSPORTATION
Networks were developed as a communication method
between computers at remote sites. They trace their roots
back to nineteenth-century communication and transportation
historical achievements. In America, people
have always strived for faster travel and communication
systems, particularly between the East and West Coasts.
These systems included technology and experiments of
varying complexity. For example, the Pony Express operated
between 1860 and 1861. It provided seven-day mail
service between St. Joseph, Missouri, and Sacramento,
California.
In 1861 the Western Union Telegraph Company
replaced the Pony Express and provided a faster, more reliable
communication service. Furthermore, the transcontinental
railroad was completed at Promontory, Utah, in
1869. These events improved the telegraph industry. The
telephone was invented in 1876, and the first transcontinental
telephone line was joined at Wendover, Utah, in
1915. This national telephone network provided a foundation
for the wide area computer networks that evolved
later in the twentieth century.
NETWORK CHARACTERISTICS
Ownership. LANs consist of computers, scanners, printers,
and cables, which are privately owned. WANs connect
computers, scanners, printers, and other devices that
sometimes may be leased or rented from public and private
telephone companies or data communication companies.
These networks place high demands on security and
reliability.
In addition, the communication line or medium that
a company uses for its network is either cable or a wireless
technology. When a business creates a WAN, it might not
manage all the lines. Sometimes a business leases lines
from a communication company. These companies are
data and voice carriers such as MCI, Sprint, Verizon,
Williams Communications, and AT&T. In these cases,
the WAN is not entirely owned by the initial business.
The business owns the line up to the point where the
handoff with the data carrier occurs. Then, the carrier
company handles the transfer of data and hands it back to

542 ENCYCLOPEDIA OF BUSINESS AND FINANCE, SECOND EDITION
Networking
the business’s private LAN network at a location many
miles away.
LAN size. The size of a LAN is set by the type of LAN
configuration and specifications. For example, a LAN in a
building might use an Ethernet technology such as
10Base2, also known as Thin Ethernet. This network
technology can have one segment 656 feet (200 meters) in
length or five linked segments up to 3,281 feet (1,000
meters) in length. A segment is the length of cable
between two computers. For 10Base2, the 10 stands for
10 megabits per second, Base means baseband, and 2
equals 200 meters. Another technology is fiber distributed
data interface (FDDI). FDDI networks can be up to 124
miles (200 kilometers) in length; these, however, are
mostly used as backbone cables that link several LANs.
WAN size. Because WANs cover large areas, they consist
of network technology that extends farther distances
than LANs. They incorporate technologies such as FDDI,
DSL (digital subscriber line), satellite, and microwave
communications. Also, they require routers, switches, and
hubs that amplify and direct signals to other routers,
switches, and hubs. They can increase their distances
nationally and globally.
Speed. Another characteristic of a computer network
is speed. Network speeds are measured in bits per second.
For example, a byte consists of 8 bits, and one alphabetic
character or numeric digit consists of 1 byte. If an average
word length is five characters and an average doublespaced
page is about 200 words, then a page (counting
words and spaces) would consist of about 9,600 bits—
((200 words¥5 characters)+199 spaces)¥8 bits. If a network
speed is 9,600 bits per second (bps), then a normal
double-spaced page is transmitted every second. If a network
speed is 56,000 bits per second (56Kbps), about six
pages of information per second would be transmitted.
LANs and WANs, however, are typically faster than
9,600 and 56,000 bps. Many networks are 10, 16, or 100
megabits per second (Mbps). A 100 Mbps network can
send 100,000,000 bits in one second—or 10,416 pages
per second. Some networks can transmit 2 billion to 8 billion
bits per second (gigabits, or Gbps). At 2 Gbps
(2,000,000,000/9600), 208,000 pages flash by every second—
more than most people read in a lifetime. Network
speeds are even reaching terabits per second. One Gbps
equals a thousand gigabits—almost unthinkable!
Signal carriers. The medium used to carry signals on
a network can be conducted or radiated. Electric signals
over wire are conducted. Fiber optic, microwave, infrared,
and radio waves are examples of radiated media.
Wire can be shielded (STP) or unshielded (UTP)
twisted pair or coaxial cable. UTP is cheaper to install
than STP or coaxial cable; therefore, it is a popular network
choice. STP or coaxial cable, however, should be
used if there is electromagnetic interference on the network.
Other networks overcome electromagnetic interference
using fiber optic lines and wireless media. They are
more expensive, however, than UTP wiring.
Twisted pair wires are rated by the American Wire
Gauge (AWG) standard. Smaller numbers mean thicker
wires. Regular telephone wire is rated a 28—too thin for
most LANs. LANs use AWG ratings between 22 and 26.
Another characteristic of twisted pair wires are the number
of twists per foot. More twists may reduce cross talk
and interference. Cross talk is when one line picks up
noise or voices from another line during a conversation or
data transmission. Usually 2 twists per foot are a minimum,
while 4 are preferred.
Furthermore, the Electronic Industries Association
(EIA) has another standard for rating wires. The EIA classifies
LAN wires for different uses. For example, Category
3 (Cat 3) must contain 3 twists per foot and is commonly
used in creating 10 Mbps LANs. Cat 5 is good for 100
Mbps and has sustained speeds up to 2 Gbps. Cat 7 reliably
supports speeds up to 600 Mbps.
Baseband versus Broadband. Currently, most LANs use
baseband transmission. Baseband means that there is one
signal transmission per line. This means the channel or
line is full when one device is sending data. It is easier for
baseband LANs than for broadband LANs to have high
speeds, behave reliably, and operate with low error rates.
Also, baseband LANs are easily monitored by network
administrators.
Broadband, on the other hand, means that the line
can handle several transmission signals at one time. This is
accomplished using different frequencies that act as separate
channels. This is called frequency division multiplexing.
Broadband networks have the capacity to handle more
channels than baseband networks, but they are more
expensive and intricate. A single cable that transmits many
television channels is an example of broadband technology.
Because of the high interest in obtaining Internet services,
broadband technology is becoming more affordable
and widespread. For example, some cities are implementing
a technology called broadband over power lines (PBL).
PBL is a computer network providing Internet data service
using broadband transmissions over public power lines.
These networks operate at speeds of 90 Mbps.
NETWORK SECURITY
Networks are diverse connections of components that are
susceptible to interference, such as unauthorized breaches
by attackers. Because of these vulnerabilities, network
administrators have ongoing challenges keeping networks
secure. Some of the vulnerabilities include eavesdropping,

ENCYCLOPEDIA OF BUSINESS AND FINANCE, SECOND EDITION 543
No Child Left Behind Legislation
viruses, denial of service (DoS), spoofing, and e-mail
bombs. These potential hazards can disrupt and curtail
the goals of effective networks. Government networks,
financial institutions, educational institutions, and specialty
businesses are highly susceptible to attackers. Some
of the methods to assure better security are established
network firewalls, computer user policies, filter rules,
incoming packet inspection mechanisms, and server isolation.
While these can be successful, they are not foolproof.
Network security planning and implementation is ongoing
and constantly improving.
Wireless networks. Wireless LANs are becoming more
useful in homes, businesses, and schools. They are also
known as Wi-Fi networks. Most of these networks use
radio waves for their transmission medium, but some use
infrared light waves. Radio waves travel free at the speed
of 186,000 miles per second. Unlike light waves, radio
waves can travel long distances and can penetrate through
nonmetallic objects. Radio waves spread out over vast
areas. Because of these advantages, wireless LAN and
WAN networks are expanding rapidly.
Interoperability. A concern on wireless networks,
interoperability results when vendors produce wireless
components that do not work together. Efforts to prevent
this from happening have been implemented. One example
is the Institute of Electrical and Electronic Engineers
(IEEE) 802.11 standard. Most wireless vendors have
agreed to follow this standard when producing wireless
components. Also, the Wireless Ethernet Compatibility
Alliance began certifying vendors who produce components
that adhere to 802.11 provisions.
Security on Wi-Fi networks is also a major concern.
Security protocols for wireless networks are provided in the
802.11i IEEE data communication standard. This standard
defines security protocols that prevent the major security
issues such as eavesdropping, spoofing, DoS, and others.
SUMMARY
Networks have become an operational necessity for just
about every business, government entity, school, and
household. Burgeoning information demands make it
necessary to link computers for efficient data sharing,
storage, and communication. E-mail services are becoming
a communication staple among computer owners.
Additionally, enhanced services such as electronic commerce,
graphics, and videoconferencing are causing networks
to grow and expand. Properly managed networks
increase productivity and assist managers and administrators
with communication demands. Consequently, networks
are an essential component of the information
system plan of every business. Networks provide a crucial advantage for end users