Types of
Networks
Local Area Networks (LANs)
A network
is any collection of independent computers that exchange information with each
other over a shared communication medium. Local Area Networks or LANs are
usually confined to a limited geographic area, such as a single building or a
college campus. LANs can be small, linking as few as three computers, but can
often link hundreds of computers used by thousands of people. The development
of standard networking protocols and media has resulted in worldwide
proliferation of LANs throughout business and educational organizations.
Wide Area
Networks (WANs)
Often
elements of a network are widely separated physically. Wide area networking
combines multiple LANs that are geographically separate. This is accomplished
by connecting the several LANs with dedicated leased lines such as a T1 or a
T3, by dial-up phone lines (both synchronous and asynchronous), by satellite
links and by data packet carrier services. WANs can be as simple as a modem and
a remote access server for employees to dial into, or it can be as complex as
hundreds of branch offices globally linked. Special routing protocols and
filters minimize the expense of sending data over vast distances.
Wireless
Local Area Networks (WLANs)
Wireless
LANs, or WLANs, use radio frequency (RF) technology to transmit and receive
data over the air. This minimizes the need for wired connections. WLANs give
users mobility as they allow connection to a local area network without having
to be physically connected by a cable. This freedom means users can access
shared resources without looking for a place to plug in cables, provided that
their terminals are mobile and within the designated network coverage area.
With mobility, WLANs give flexibility and increased productivity, appealing to both
entrepreneurs and to home users. WLANs may also enable network administrators
to connect devices that may be physically difficult to reach with a cable.
The
Institute for Electrical and Electronic Engineers (IEEE) developed the 802.11
specification for wireless LAN technology. 802.11 specifies over-the-air
interface between a wireless client and a base station, or between two wireless
clients. WLAN 802.11 standards also have security protocols that were developed
to provide the same level of security as that of a wired LAN.
The first of these protocols is Wired Equivalent Privacy (WEP). WEP provides security by encrypting data sent over radio waves from end point to end point.
The first of these protocols is Wired Equivalent Privacy (WEP). WEP provides security by encrypting data sent over radio waves from end point to end point.
The second
WLAN security protocol is Wi-Fi Protected Access (WPA). WPA was developed as an
upgrade to the security features of WEP. It works with existing products that
are WEP-enabled but provides two key improvements: improved data encryption
through the temporal key integrity protocol (TKIP) which scrambles the keys
using a hashing algorithm. It has means for integrity-checking to ensure that
keys have not been tampered with. WPA also provides user authentication with
the extensible authentication protocol (EAP).
Types of
LAN Technology
Ethernet
Ethernet is
the most popular physical layer LAN technology in use today. It defines the
number of conductors that are required for a connection, the performance
thresholds that can be expected, and provides the framework for data
transmission. A standard Ethernet network can transmit data at a rate up to 10
Megabits per second (10 Mbps). Other LAN types include Token Ring, Fast
Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet, Fiber Distributed Data
Interface (FDDI), Asynchronous Transfer Mode (ATM) and LocalTalk.
Ethernet is
popular because it strikes a good balance between speed, cost and ease of
installation. These benefits, combined with wide acceptance in the computer
marketplace and the ability to support virtually all popular network protocols,
make Ethernet an ideal networking technology for most computer users today.
The
Institute for Electrical and Electronic Engineers developed an Ethernet
standard known as IEEE Standard 802.3. This standard defines rules for
configuring an Ethernet network and also specifies how the elements in an
Ethernet network interact with one another. By adhering to the IEEE standard,
network equipment and network protocols can communicate efficiently.
Fast
Ethernet
The Fast
Ethernet standard (IEEE 802.3u) has been established for Ethernet networks that
need higher transmission speeds. This standard raises the Ethernet speed limit
from 10 Mbps to 100 Mbps with only minimal changes to the existing cable
structure. Fast Ethernet provides faster throughput for video, multimedia,
graphics, Internet surfing and stronger error detection and correction.
There are
three types of Fast Ethernet: 100BASE-TX for use with level 5 UTP cable;
100BASE-FX for use with fiber-optic cable; and 100BASE-T4 which utilizes an
extra two wires for use with level 3 UTP cable. The 100BASE-TX standard has
become the most popular due to its close compatibility with the 10BASE-T
Ethernet standard.
Network
managers who want to incorporate Fast Ethernet into an existing configuration
are required to make many decisions. The number of users in each site on the
network that need the higher throughput must be determined; which segments of
the backbone need to be reconfigured specifically for 100BASE-T; plus what
hardware is necessary in order to connect the 100BASE-T segments with existing
10BASE-T segments. Gigabit Ethernet is a future technology that promises a
migration path beyond Fast Ethernet so the next generation of networks will
support even higher data transfer speeds.
Gigabit
Ethernet
Gigabit
Ethernet was developed to meet the need for faster communication networks with
applications such as multimedia and Voice over IP (VoIP). Also known as
“gigabit-Ethernet-over-copper” or 1000Base-T, GigE is a version of Ethernet
that runs at speeds 10 times faster than 100Base-T. It is defined in the IEEE
802.3 standard and is currently used as an enterprise backbone. Existing
Ethernet LANs with 10 and 100 Mbps cards can feed into a Gigabit Ethernet
backbone to interconnect high performance switches, routers and servers.
From the
data link layer of the OSI model upward, the look and implementation of Gigabit
Ethernet is identical to that of Ethernet. The most important differences
between Gigabit Ethernet and Fast Ethernet include the additional support of
full duplex operation in the MAC layer and the data rates.
10 Gigabit
Ethernet
10 Gigabit
Ethernet is the fastest and most recent of the Ethernet standards. IEEE 802.3ae
defines a version of Ethernet with a nominal rate of 10Gbits/s that makes it 10
times faster than Gigabit Ethernet.
Unlike
other Ethernet systems, 10 Gigabit Ethernet is based entirely on the use of
optical fiber connections. This developing standard is moving away from a LAN
design that broadcasts to all nodes, toward a system which includes some
elements of wide area routing. As it is still very new, which of the standards
will gain commercial acceptance has yet to be determined.
Asynchronous
Transfer Mode (ATM)
ATM is a
cell-based fast-packet communication technique that can support data-transfer
rates from sub-T1 speeds to 10 Gbps. ATM achieves its high speeds in part by
transmitting data in fixed-size cells and dispensing with error-correction
protocols. It relies on the inherent integrity of digital lines to ensure data
integrity.
ATM can be
integrated into an existing network as needed without having to update the entire
network. Its fixed-length cell-relay operation is the signaling technology of
the future and offers more predictable performance than variable length frames.
Networks are extremely versatile and an ATM network can connect points in a
building, or across the country, and still be treated as a single network.
Power over
Ethernet (PoE)
PoE is a
solution in which an electrical current is run to networking hardware over the
Ethernet Category 5 cable or higher. This solution does not require an extra AC
power cord at the product location. This minimizes the amount of cable needed
as well as eliminates the difficulties and cost of installing extra outlets.
Types of
Internet Connections
Broadband
Broadband internet connections provide high-speed internet
that is always on and allows for more data to be transmitted than the
traditional dial-up connections. Unlike dial-up services, it does not block
phone lines and you do not have to reconnect to the network each time you log
off. There are various types of broadband technologies, including digital
subscriber line (DSL), cable modems, fibers, wireless broadband connections,
and Satellite connections. The fastest of these connections is by far the fiber
broadband, outperforming DSL and cable modems by ten to even hundreds of Mbps.
Wireless connections perform at a speed similar to DSL and cable modems, while
satellites are slower than DSL, but still much faster than traditional dial-up
internet.
Wi-Fi
Wi-Fi is a play on the term Hi-Fi and represents a wireless
internet connection. More specifically, it is a wireless local area network (WLAN) that allows
devices to connect wirelessly to the internet. It utilizes 2.4 GHz and 5.0 GHz
radio waves to connect Wi-Fi enabled gadgets (computers, gaming systems, mobile
phones, and even some cameras) to the internet without the need for cumbersome
wires. These connections can be extremely fast in some cases, reaching speeds
of over 100 Mbps, but the convenience of having no cables and the increased
speed come at a cost of potentially decreased security. Because there is no
need for a physical connection, it is easier for hackers to compromise the
security of Wi-Fi connections.
WiMAX
WiMAX is a more advanced form of wireless internet technology
than Wi-Fi. It aims to provide the high speeds of broadband connections, the
large coverage of phone networks, and the convenience of Wi-Fi into one
package. The implementation of WiMAX would allow DSL and cable modem users to
ditch their wired internet connections in favor of a high-speed, wireless
alternative. Even those users in rural areas who find wireless internet or even
phone coverage difficult to come by would be able to connect to the internet
via WiMAX due to its very broad coverage. If WiMAX is mastered, the way that
people access the internet worldwide would be revolutionized.
Computer
Networking: The Server
What is a server? – In
information technology, a server is considered any instance of an application
that can receive and serve the requests of other programs. Usually these
applications are run on computers dedicated to acting solely as servers so that
the heavy burden of fulfilling requests from other devices on the network does
not overwhelm the computers. Running servers on dedicated computers is also a
safety measure, helping to keep the server from being attacked. The computers
dedicated to acting as servers usually include faster CPUs, bigger hard drives,
better RAM, and multiple power sources. These enhancements allow the server to
handle the immense workload and also give it reliability in the event of unfortunate
events.
Peer-to-Peer
Networks
A Peer-to-Peer network,
or P2P network,
is one in which multiple computers are connected without linking through a
separate computer that acts as a server. These connections can vary based on
how many computers are being linked together. Two computers can be linked via a
USB drive to allow for the transfer of files. Multiple computers in an office
can be connected directly to each other via traditional copper wiring instead
of through a server computer. The fundamental basis for P2P networks is that
individual permissions must be set for each computer on the network. For
instance, if one computer (A) is connected to a printer and another computer
(B) on the network wishes to use the printer, then A would first have to grant
B permission.