study about different network devices

this is very useful to 5th sem engineering students in GTU and all indian universities...

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Experiment - 1
Aim: Study of different network devices in detail.
 NIC
 Hub
 Switch
 Cables and Connectors
 Router
 Modem
1. Network Interface Card (NIC)
In the list of the networking devices, NIC stands on the first place. Without this device, networking
cannot be done. This is also known as network adapter card, Ethernet Card and LAN card. NIC allows
a networking device to communicate with the other networking device.
NIC converts the data packets between two different data transmission technologies. A PC uses
parallel data transmission technology to transmit the data between its internal parts while the media
that provides connectivity between different PCs uses serial data transmission technology.

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Types of NICs
There are two types of NICs.
Media Specific : -
LAN card are used according to the media type. Different types of the NICs are used to connect the
different types of media. To connect a specific media type, we must have to use a NIC which is
particularly made for that type of media.
Network Design Specific: -
A specific network design needs a specific LAN card. For example FDDI, Token Ring and Ethernet
have their own distinctive type of NIC cards. They cannot use other types of NIC cards.

2. Hub
A hub is basically a multiport repeater. A hub connects multiple wires coming from different
branches, for example, the connector in star topology which connects different stations. Hubs cannot
filter data, so data packets are sent to all connected devices. In other words, collision domain of all
hosts connected through Hub remains one. Also, they do not have intelligence to find out best path
for data packets which leads to inefficiencies and wastage.


Types of Hub

 Active Hub:- These are the hubs which have their own power supply and can clean, boost
and relay the signal along with the network. It serves both as a repeater as well as wiring
centre. These are used to extend the maximum distance between nodes.

 Passive Hub :- These are the hubs which collect wiring from nodes and power supply from
active hub. These hubs relay signals onto the network without cleaning and boosting them and
can’t be used to extend the distance between nodes.

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3. Switch
A switch is a multiport bridge with a buffer and a design that can boost its efficiency(a large number
of ports imply less traffic) and performance. A switch is a data link layer device. The switch can
perform error checking before forwarding data, that makes it very efficient as it does not forward
packets that have errors and forward good packets selectively to correct port only. In other words,
switch divides collision domain of hosts, but broadcast domain remains same.


4. Cables and connectors

Cables :-
 Thick Coaxial Cable
This type cable is usually yellow in color and used in what is called thicknets, and has two
conductors. This coax can be used in 500-meter lengths. The cable itself is made up of a solid
center wire with a braided metal shield and plastic sheathing protecting the rest of the wire.
 Thin Coaxial Cable
As with the thick coaxial cable is used in thicknets the thin version is used in thinnets. This
type cable is also used called or referred to as RG-58. The cable is really just a cheaper
version of the thick cable.
 Fiber Optic Cable
Fiber optic cabling consists of a center glass core surrounded by several layers of protective
materials. It transmits light rather than electronic signals eliminating the problem of electrical
interference. This makes it ideal for certain environments that contain a large amount of electrical
interference. It has also made it the standard for connecting networks between buildings, due to its
immunity to the effects of moisture and lighting.
Fiber optic cable has the ability to transmit signals over much longer distances than coaxial and
twisted pair. It also has the capability to carry information at vastly greater speeds. This capacity

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broadens communication possibilities to include services such as video conferencing and interactive
services. The cost of fiber optic cabling is comparable to copper cabling; however, it is more
difficult to install and modify. 10BaseF refers to the specifications for fiber optic cable carrying
Ethernet signals.
There are two common types of fiber cables — single mode and multimode. Multimode cable has a
larger diameter; however, both cables provide high bandwidth at high speeds. Single mode can
provide more distance, but it is more expensive.

 Twisted Pair Cables
These come in two flavors of unshielded and shielded.
Shielded Twisted Pair (STP)
Is more common in high-speed networks. The biggest difference you will see in the UTP and STP is
that the STP use’s metallic shield wrapping to protect the wire from interference.
-Something else to note about these cables is that they are defined in numbers also. The bigger the
number the better the protection from interference. Most networks should go with no less than a
CAT 3 and CAT 5 is most recommended.

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Unshielded Twisted Pair (UTP)
This is the most popular form of cables in the network and the cheapest form that you can go with.
The UTP has four pairs of wires and all inside plastic sheathing. The biggest reason that we call it
Twisted Pair is to protect the wires from interference from themselves. Each wire is only protected
with a thin plastic sheath.



 Ethernet Cabling
Now to familiarize you with more on the Ethernet and it’s cabling we need to look at the 10’s.
10Base2, is considered the thin Ethernet, thinnet, and thinwire which uses light coaxial cable to
create a 10 Mbps network. The cable segments in this network can’t be over 185 meters in length.
These cables connect with the BNC connector. Also as a note these unused connection must have a
terminator, which will be a 50-ohm terminator.

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Connectors –
 Unshielded Twisted Pair Connector
The standard connector for unshielded twisted pair cabling is an RJ-45 connector. This is a plastic
connector that looks like a large telephone-style connector . A slot allows the RJ-45 to be inserted
only one way. RJ stands for Registered Jack, implying that the connector follows a standard
borrowed from the telephone industry. This standard designates which wire goes with each pin
inside the connector.
RJ45


 Coaxial Cable Connectors
The most common type of connector used with coaxial cables is the Bayone-Neill-Concelman
(BNC) connector. Different types of adapters are available for BNC connectors, including a T-
connector, barrel connector, and terminator. Connectors on the cable are the weakest points in any
network. To help avoid problems with your network, always use the BNC connectors that crimp,
rather screw, onto the cable.
LAN card –

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5. Routers

A router is a device like a switch that routes data packets based on their IP addresses. Router is mainly
a Network Layer device. Routers normally connect LANs and WANs together and have a dynamically
updating routing table based on which they make decisions on routing the data packets. Router divide
broadcast domains of hosts connected through it.



Basically routers are used: -
 To connect different network segments.
 To connect different network protocols such as IP and IPX.
 To connect several smaller networks into a large network (known as the Internetwork)
 To break a large network into smaller networks (Known as the Subnets. Usually created to
improve the performance or manageability.)
 To connect two different media types such as UTP and Fiber optical.
 To connect two different network architectures such as Token Ring and Ethernet.
 To connect LAN network with Telco company’ office (Known as the DTE device).
 To access DSL services (known as the DSL Router).

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6. Modem
Modem is a device that enables a computer to send or receive data over telephone or cable lines. The
data stored on the computer is digital whereas a telephone line or cable wire can transmit only analog
data.
The main function of the modem is to convert digital signal into analog and vice versa. Modem is a
combination of two devices − modulator and demodulator. The modulator converts digital data
into analog data when the data is being sent by the computer. The demodulator converts analog data
signals into digital data when it is being received by the computer.

Types of Modem
Modem can be categorized in several ways like direction in which it can transmit data, type of
connection to the transmission line, transmission mode, etc.
Depending on direction of data transmission, modem can be of these types −
 Simplex − A simplex modem can transfer data in only one direction, from digital device to
network (modulator) or network to digital device (demodulator).
 Half duplex − A half-duplex modem has the capacity to transfer data in both the directions
but only one at a time.
 Full duplex − A full duplex modem can transmit data in both the directions simultaneously.