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Introduction
Network components and
devices are the physical entities connected to a network. There are
many types of network devices and increasing daily. The basic
network devices are: Computers (either a PC or a Server), Hubs,
Switches, Bridges, Routers, Gateways, Network interface cards (NICs),
Wireless access points (WAPs), Printers and Modems. The following is
a overview of the main network components and devices:
Individual
Computers: The personal computer is typically a desktop
computer, a workstation or a notebook for individual users. The
individual computers are the most common type of microcomputer and
is found in the majority of organizations.
Server:
A computer on a network or other network device that stores all
necessary information and is dedicated to provide a particular
service. For example, a database server would store all data and
software related to a certain database and allows other network
devices to access and process database queries. A file server is a
computer and storage device dedicated to storing files for any user
on the network to store files on the server. A print server is a
device that manages one or more printers, and a network server is a
computer that manages network traffic. In many cases, a single
machine can carry out many of these functions.
Network
Interface Card: Network Interface Cards (NICs) are adaptors
attached with a computer or other network device to provide the
connection between the computer with the network. Each NIC is design
for a specific type of network such as Ethernet, Token Ring, FDDI or
wireless LAN. The NIC operates using the physical layer (layer 1)
and data link layer (layer 2) specifications. NIC basically defines
the physical connection methods with the cable and the framing
methods used to transmit bit streams over the network. It also
defines the control signals that provide the timing of data
transfers across network.
Hubs:
Hubs are the simplest network devices. Computers connect to a hub
via a length of twisted-pair cabling. On a hub, data is forwarded to
all ports, regardless of whether the data is intended for the system
connected to the port. In addition to ports for connecting
computers, even a very inexpensive hub generally has a port
designated as an uplink port that enables the hub to be connected to
another hub to create larger networks.
Switches: Switch
is a layer 2 and multi-port device. Switch provides similar
functions as a hub or a bridge but has more advanced features that
can temporarily connect any two ports together. It contains a switch
matrix or switch fabric that can rapidly connect and disconnect
ports. Unlike Hub, a switch only forwards frames from one port to the
other port where the destination node is connected without broadcast
the frame to all other ports.
Routers:
Routers route data around the network from data senders to
receivers. A router is able to determine the destination address for
the data and determines the best way for the data to continue its
journey. Unlike bridges and switches, which use the
hardware-configured MAC address to determine the destination of the
data, routers use the logic network address such as IP address to
make decisions.
See the
Hubs, Switches and Routers
page to get a better idea of how these devices can work in your
network.
Gateway:
The term gateway is applied to any device, system, or
software application that can perform the function of translating
data from one format to another. Gateway will not change the data
itself. For example, a router that can route data from an IPX
network to an IP network is, technically, a gateway. The same can be
said of a translational switch that converts from an Ethernet
network to a Token Ring network and back again.
Modems:
Modems are access devices that translate digital signals from a
computer into analog signals that can travel across conventional
phone lines. The modem modulates the signal at the sending end and
demodulates at the receiving end. Modems are required for many
access methods such as satellite internet access, 56k data modern, ISDN, DSL etc. They can be
used as internal devices that plug into expansion slots in a system;
external devices that plug into serial or USB ports; PCMCIA cards
designed for use in laptops; and specialized devices designed for
use in systems such as handheld computers. In addition, many laptops
now come with integrated modems. For large-scale modem
implementations, such as at an ISP, rack-mounted modems are also
available.
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