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Practical 1,2,3 (computer network)

Masters in computer applicaitions (I. K. Gujral Punjab Technical University)

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Practical 1: Familiarization with networking components and devices: LAN,

Adapters, Hubs, Switches, Routers etc.
LAN Adapters: -
A LAN adapter is a device used to allow a computer to interface with a network. Many
computers may have some sort of LAN adapter already installed, but others may require a
special installation, which is accomplished by adding a network interface card to the
system or possibly connecting the adapter to a USB port.

Wireless USB LAN Adapter: -

A high-speed wireless network card that is used to access a network through a USB port
on a computer or laptop. Most wireless USB LAN adapters look like small USB flash
drives and usually are based on the 802.11g standard which provides a data rate up to 54-
Mbps in a wireless LAN environment. Some wireless USB LAN adapters may also
support the 802.11b standard. A wireless USB LAN adapter basically enables you to
share files, folders, printers, other network resources and internet access.

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Hubs: -
Hub is a unique device used to enhance a network by enabling increased workstations in
the network.
The three main types of Hubs are as follows:

1). Passive Hub

Passive hubs do not include any computerized elements, and they do not procedure the
data signal at all. The main goal of a passive hub is to connect the signals from various
network cable segments. All devices connected to a passive hub take all the packets that
develop through the hub.
One example of the passive hub is the punch down block consisting of a plastic box with
different connectors (mostly RJ 45). This hub is an unpowered or powerless passive hub.
The other passive hubs are generally powered passive hubs, and they are used as the
central block of the star network. The Multistation Access Unit (MAU)is an example of
the powered passive hub used in token ring networks.
2). Active Hub
The hubs that contain repeating capabilities to strengthen the signals in a network are
called active hubs. The limitation of active hubs is that they magnify noise along with
the signals. They are a little brighter than passive hubs because they boost the signals
before passing them between nodes to the node. They are also called concentrators and
can accommodate more one than one set of network connections.

3). Intelligent Hub

These hubs are also called smart hubs. They have a special kind of software in them to
perform management functions in the network. The software offers them the capability
to find and separate network issues. Thus, they have both monitoring and management
capabilities.
These hubs do not have much importance in smaller networks with a few nodes, but as
the network expands, its problems and management need also increase, and in those
networks, such hubs are proved to be an asset.
They can keep track of how each node is doing in the network and can take action to
correct the problems occurring in the network. As troubleshooting in larger networks
manually is not easy, smart hubs play a vital role in such networks.

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Switches:
o When a user accesses the internet or another computer network outside their
immediate location, messages are sent through the network of transmission
media. This technique of transferring the information from one computer network
to another network is known as switching.
o Switching in a computer network is achieved by using switches. A switch is a
small hardware device which is used to join multiple computers together with one
local area network (LAN).
o Network switches operate at layer2 (Data link layer) in the OSI model.
o Switching is transparent to the user and does not require any configuration in the
home network.
o Switches are used to forward the packets based on MAC addresses.
o A Switch is used to transfer the data only to the device that has been addressed. It
verifies the destination address to route the packet appropriately.
o It is operated in full duplex mode.
o Packet collision is minimum as it directly communicates between source and
destination.
o It does not broadcast the message as it works with limited bandwidth.

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Routers:
Routers are networking devices operating at layer 3 or a network layer of the OSI model.
They are responsible for receiving, analysing, and forwarding data packets among the
connected computer networks. When a data packet arrives, the router inspects the
destination address, consults its routing tables to decide the optimal route and then
transfers the packet along this route.

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Practical 2: Familiarization with transmission media and tools: Coaxial cables,

UTP cables, Crimping tools, Connectors etc.

What is Transmission media?

o Transmission media is a communication channel that carries the information from
the sender to the receiver. Data is transmitted through the electromagnetic
signals.
o The main functionality of the transmission media is to carry the information in the
form of bits through LAN (Local Area Network).
o It is a physical path between transmitter and receiver in data communication.
o In a copper-based network, the bits in the form of electrical signals.
o In a fibre-based network, the bits in the form of light pulses.

Guided media
Guided Media is also known as Wired or Bounded transmission media. A signal
travelling the media is directed and confined by the physical limits of the medium.

Three Types of Guided Media:

There are three types of guided media which are Twisted-Pair cable, Coaxial Cable and
Fiber-optic cable.

Unguided media
An unguided media type transmission is used to transmit electromagnetic waves without
using any of the physical transmission media. Thus, it is also called wireless
transmission. Unguided media type includes air as the media where electromagnetic
energy can be flown easily without any intrusion or hindrance. Radio waves are the

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electromagnetic waves which are transmitted in all the directions of free spaces in an
omnidirectional way i.e.,

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signals get transmitted in all the direction and is used widely in propagating the signals
mainly for telecommunication.

Coaxial cables
Coaxial cable consists of a hollow outer cylindrical conductor that surrounds a single
inner wire conducting element. As shown in Figure, the single inner wire located in the
center of a coaxial cable is a copper conductor, surrounded by a layer of flexible
insulation. Over this insulating material is a metallic foil that acts both as the second
wire in the circuit and as a shield for the inner conductor. This second layer, or shield,
can help reduce the amount of outside interference. An outer jacket covers this shield.
The BNC connector shown looks much like a cable television connector and connects to
an older NIC with a BNC interface.

UTP Cable
Unshielded twisted pair (UTP) cables are widely used in the computer and
telecommunications industry as Ethernet cables and telephone wires.

In an UTP cable, conductors which form a single circuit are twisted around each other in
order to cancel out electromagnetic interference (EMI) from external sources.
Unshielded means no additional shielding like meshes or aluminium foil, which add
bulk, are used.
UTP cables are often groups of twisted pairs grouped together with colour coded
insulators, the number of which depends on the purpose.

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Crimping tools

A crimping tool is a device that is used to make cold weld joints between wires and a
connector through deforming one or both of them to hold the other. A special
connector is used to join metals together. The weld joint properties (mechanical and
electrical) are strong as the parent materials when the tool works and offer some
result, which is known a scrimp. An instance of crimping is to be affixing a connector to
the end of a wire. For example, a crimping tool is used to create phone cables and
network cables to combine RJ-11 and RJ-45 connectors to both ends of the phone or
Cat 5 cable. The below picture is an example of RJ-11 (6-pin) and RJ-45 (8-pin) crimping
tools.

RJ-45 Connecter
The RJ-45 connector is a form of telephone connector. It sees its most frequent use as a
local area network connector and is frequently referred to simply as an Ethernet
connector.

BNC Connecter
This connector is commonly used on a Token Ring network. BNC is also short for
Bayonet Nut Connector or British Naval/Navy Connector although more appropriately
known as the Bayonet Neill Concelman. In the picture to the right, is an example of a
BNC connector on the end of a coaxial cable.

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Practical 3: Preparing Straight and cross cables.

Straight-Through Wired Cables
Straight-Through refers to cables that have the pin assignments on each end
of the cable. In other words, Pin 1 connector A goes to Pin 1 on connector B,
Pin 2 to Pin 2 etc. Straight- Through wired cables are most commonly used
to connect a host to client. When we talk about cat5e patch cables, the
Straight-Through wired cat5e patch cable is used to connect computers,
printers and other network client devices to the router switch or hub (the host

device in this instance).

Crossover Wired Cables:

An Ethernet cross over cable is a type of Ethernet cable used to connect
computing devices together directly. Normal straight through or patch cables

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were used to connect from a host network interface controller (a computer or

similar device) to a network switch, hub, or router. A cable with connections
that "crossover" was used to connect two devices of the same type: two hosts
or two switches to each other.

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