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Network cables and network topologies

   

Added on  2022-06-14

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PRACTICAL FILE
OF

COMPUTER NETWORKS

Submitted by-Nargisdeep kaur

Class-B.Tech CSE 5TH

URN-1903346

Submitted to-Ms. Varsha Saini

Sub Code: BTCS 507-18 1903346
Page 2

Practical 1: To study the different types of Network cables and network topologies.
Apparatus Required:
Theory: Network Cabling: Cable is the medium through which information usually
moves from one network device to another. There are several types of cable which are
commonly used with LANs. In some cases, a network will utilize only one type of cable, other
networks will use a variety of cable types. The type of cable chosen for a network is related to
the network's topology, protocol, and size. Understanding the characteristics of different types
of cable and how they relate to other aspects of a network is necessary for the development of a
successful network.
The following sections discuss the types of cables used in networks and other related topics.
Twisted pair cabling comes in two varieties: shielded and unshielded. Unshielded twisted pair
(UTP) is the most popular and is generally the best option for school networks

Fig.1. Unshielded twisted pair

The
quality of UTP may vary from telephone-grade wire to extremely high-speed cable. The
cable has four pairs of wires inside the jacket. Each pair is twisted with a different number of

twists per inch to help eliminate interference from adjacent pairs and oth
er electrical devices.
The tighter the twisting, the higher the supported transmission rate and the greater the cost

per foot. The EIA/TIA (Electronic Industry Association/Telecommunication Industry

Association) has established standards of UTP and rated s
ix categories of wire (additional
categories are emerging).

Categories of Unshielded Twisted Pair

Category
Speed Use
1
1 Mbps Voice Only (Telephone Wire)

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2
4 Mbps Local Talk & Telephone (Rarely used)
3
16 Mbps 10BaseT Ethernet
4
20 Mbps Token Ring (Rarely used)
5
100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair)
Gigabit Ethernet
5e
1,000 Mbps Gigabit Ethernet
6
10,000 Mbps Gigabit Ethernet
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 (See fig. 2). 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 th
e telephone industry. This standard designates which wire
goes with each pin inside the connector.

Fig. 2. RJ
-45 connector
Shielded Twisted Pair (STP) Cable

Although UTP cable is the least expensive cable, it may be susceptible to radio and electrical

frequency interference (it should not be too close to electric motors, fluorescent lights, etc.). If you

must place cable in environments with lots of potential interference, or if you must place cable in

extremely sensitive environments that may be suscep
tible to the electrical current in the UTP,
shielded twisted pair may be the solution. Shielded cables can also help to extend the maximum

distance of the cables.

Shielded twisted pair cable is available in three different configurations:

1.
Each pair of wires is individually shielded with foil.
2.
There is a foil or braid shield inside the jacket covering all wires (as a group).

Sub Code: BTCS 507-18 1903346
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3.
There is a shield around each individual pair, as well as around the entire group of wires
(referred to as double shield twisted pair).

Coaxial Cable

Coaxial cabling has a single copper conductor at its center. A plastic layer provides insulation

between the center conductor and a braided metal shield (See fig. 3). The metal shield helps to

block any outside interference from fluorescent
lights, motors, and other computers.
Fig. 3. Coaxial cable

Although coaxial cabling is difficult to install, it is highly resistant to signal interference. In

addition, it can support greater cable lengths between network devices than twisted pair cable.
The
two types of coaxial cabling are thick coaxial and thin coaxial.

Thin coaxial cable is also referred to as thinnet. 10Base2 refers to the specifications for thin coaxial

cable carrying Ethernet signals. The 2 refers to the approximate maximum segment
length being
200 meters. In actual fact the maximum segment length is 185 meters. Thin coaxial cable has been

popular in school networks, especially linear bus networks.

Thick coaxial cable is also referred to as thicknet. 10Base5 refers to the specificati
ons for thick
coaxial cable carrying Ethernet signals. The 5 refers to the maximum segment length being 500

meters. Thick coaxial cable has an extra protective plastic cover that helps keep moisture away

from the center conductor. This makes thick coaxial
a great choice when running longer lengths in
a linear bus network. One disadvantage of thick coaxial is that it does not bend easily and is

difficult to install.

Coaxial Cable Connectors

The most common type of connector used with coaxial cables is the
Bayone-Neill-Concelman
(BNC) connector (See fig. 4). 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 probl
ems with your network, always use the BNC connectors
that crimp, rather screw, onto the cable.

Fig. 4. BNC connector

Sub Code: BTCS 507-18 1903346
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Fiber Optic Cable

Fiber optic cabling consists of a center glass core surrounded by several layers of protective

materials (See fig. 5).
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 netwo
rks 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 gr
eater speeds. This capacity
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.

The center core of fiber cables is made from glass or plastic fibers (see fig 5). A plastic coating then

cushions the fiber center, and kevlar fibers help to strengthen t
he cables and prevent breakage. The
outer insulating jacket made of teflon or PVC.

Fig. 5. Fiber optic cable

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.

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.

Specification
Cable Type
10BaseT
Unshielded Twisted Pair
10Base2
Thin Coaxial
10Base5
Thick Coaxial
100BaseT
Unshielded Twisted Pair
100BaseFX
Fiber Optic
100BaseBX
Single mode Fiber

Sub Code: BTCS 507-18 1903346
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100BaseSX
Multimode Fiber
1000BaseT
Unshielded Twisted Pair
1000BaseFX
Fiber Optic
1000BaseBX
Single mode Fiber
1000BaseSX
Multimode Fiber
Installing Cable
- Some Guidelines
When running cable, it is best to follow a few simple rules:

Always use more cable than you need. Leave plenty of slack.
Test every part of a network as you install it. Even if it is brand new, it may have problems
that will be difficult to isolate later.

Stay at least 3 feet away from fluorescent light boxes and other sources of electrical
interference.

If it is necessary to run cable across the floor, cover the cable with cable protectors.
Label both ends of each cable.
Use cable ties (not tape) to keep cables in the same location together.
Wireless LANs

More and more networks are operating without cables, in the wireless mode. Wireless LANs use
high frequency radio signals, infrared light beams, or lasers to communicate between the
workstations, servers, or hubs. Each workstation and file server on a wireless network has some
sort of transceiver/antenna to send and receive the data. Information is relayed between transceivers
as if they were physically connected. For longer distance, wireless communications can also take
place through cellular telephone technology, microwave transmission, or by satellite.
Wireless networks are great for allowing laptop computers, portable devices, or remote computers
to connect to the LAN. Wireless networks are also beneficial in older buildings where it may be
difficult or impossible to install cables.

The two most common types of infrared communications used in schools are line
-of-sight and
scattered broadcast. Line
-of-sight communication means that there must be an unblocked direct line
between the workstation and the transceiver. If a
person walks within the line-of-sight while there

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