Lecture 13-Fundamentals_of_Networking.ppt

Introduction to computer systems, fundamentals of networking

1. CST2021
INTRODUCTION TO
COMPUTER SYSTEMS
Lecture 13
Fundamentals of Networking

2. Outline

Communication Media

3. Types of Communication Media

Cables
•Cable is the medium through which information usually
moves from one device to another.
•Twisted Pair
•UTP- Unshielded Twisted Pair
•STP- Shielded twisted pair
•Coaxial
•Fiber Optic

Wireless
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4. Twisted-Pair Cabling

A pair of twisted wires forms a
circuit that transmits data.

Relies on the cancellation effect for
reduction of interference caused by
electromagnetic interface (EMI)
•Pairs of copper wires are
encased in color-coded plastic
insulation and twisted together.
•An outer jacket, called poly-
vinyl chloride (PVC), protects
the bundles of twisted pairs.
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5. Unshielded twisted-pair (UTP)
•Has two or four pairs of wires
•Each pair is twisted with a
different number of twists per
inch to help eliminate
interference from adjacent pairs
and other electrical devices.
•Most commonly used cabling in
networks
•Has a range of 328 ft (100
meters)
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6. UTP
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7. Shielded twisted-pair (STP)
•Each pair is wrapped in
metallic foil to better shield
the wires from electrical
noise and then the four pairs
of wires are then wrapped in
an overall metallic braid or
foil.
•Reduces electrical noise
from within the cable.
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8. Category Rating

UTP comes in several categories that are based on
two factors:
•The number of wires in the cable
•The number of twists in those wires

Category 3 is used for telephone connections.

Category 5 and Category 5e are the most common
network cables used.

Category 6 cable has higher data rate than the Cat
5 cables.
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9. Coaxial

A copper-cored network cable
surrounded by a heavy shielding

Types of coaxial cable:
•Thicknet or 10Base5 - Coax cable
that was used in networks and
operated at 10 megabits per second
with a maximum length of 500 m
•Thinnet or 10Base2 - Coax cable
that was used in networks and
operated at 10 megabits per second
with a maximum length of 185 m
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10. Fiber-Optic Cable

A glass or plastic strand that transmits
information using light and is made up of
one or more optical fibers enclosed together
in a sheath or jacket.

Not affected by electromagnetic or radio
frequency interference.

Signals are clearer, can go farther, and have
greater bandwidth than with copper cable.

Usually more expensive than copper cabling
and the connectors are more costly and
harder to assemble.
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11. Fiber Optic Cable

Two forms;

12. Wireless
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13. Wireless

Bluetooth
• uses the 2.4 GHz band.
• limited to low-speed
•short-range communications

Infrared
•relatively low energy and cannot penetrate through walls or other
obstacles.
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14. UTP Cables - T568A and T568B

Each wiring scheme defines the pinout, or order of wire
connections, on the end of the cable.

On a network installation, one of the two wiring schemes
(T568A or T568B) should be chosen and followed.

15. Straight Through

It maps a wire to the same pins on both ends of the cable.

Two devices directly connected and using different pins for transmit and
receive are known as unlike devices. They require a straight-through
cable to exchange data.
•PC to Switch
•Switch port to router port
•Hub port to PC

16. Cross-over

A crossover cable uses both wiring schemes. T568A on one end of the cable and
T568B on the other end of the same cable.

Devices that are directly connected and use the same pins for transmit and receive, are
known as like devices. They require the use of a crossover cable to exchange data.
•Switch port to switch port
•Switch port to hub port
•Hub port to hub port
•Router port to router port
•PC to router port
•PC to PC

17. UTP Cable Termination

UTP and STP cable is usually terminated into an
RJ-45 connector.

18. Terminating UTP at patch panels and wall jacks.

19. Cable Testing

It is important to verify that the cable operates
correctly and meets connectivity standards

20. Cable Testing

Continuity test
•verifies that there is end-to-end connectivity.

Common cabling faults - opens and shorts.
•An open circuit occurs when the wire is not properly pushed into
the connector and there is no electrical contact. An open can also
occur if there is a break in the wire.
•A short occurs when the copper conductors touch each other. As
the electric pulse travels down the wire, it will cross onto the
touching wire. This creates an unintended path in the flow of the
signal to its destination.

21. Cable Best Practices

Adhere to the standards required for that network

Always follow the rules for cable termination and
test to verify that the termination has been done
properly.

Organized cabling system that can be easily
understood by installers, network administrators,
and any other technicians who deal with cables.