Transcript Slide 1

Cyberspace
Internet Components
With this presentation we intend to present the
different components/equipments that allow us
to connect and browse the Web.
Communication protocols
Internet connection equipment
Transmission Means
Transmission Means
A physical means of transmission in a computer
network is the communication channel, by
which, computers send and receive signals that
encode information.
The most currently used is the wireless.
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Electric cables
Optical cables
Wireless
Electric cables
The copper cable transmit electrical signals at a high
frequency to relatively long distances.
They are vulnerable to external electromagnetic
interference.
Copper cables are composed of four pairs of copper wires
that are twisted together, protecting transmissions from
Main conductor
Shield
outside interference.
Copper wire
Copper wire webbing
Dielectric
Solid plastic
Externel protection
Anti-fire flexible polyvinyl chloride
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Electric versus Optical cables
Transmission Means
Optical cables
The optical fiber cables using the phenomenon
of total internal refraction of light beams to
pass over long distances.
A very thin glass core, made of silica with high
purity is surrounded by a layer (also silica)
with refractive index lower cladding call,
which causes the light transmitted by the fiber
core is reflected the inner walls of the cable.
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Electric versus Optical cables
Transmission Means
Electric Cables Vs Optical Cables
Optical Cables
Advantages
Disadvantages
•Thickness allows the inclusion of a
large volume of wire in one cable.
• Immune to electromagnetic
interference.
• High transmission rate.
• Carry digital signals without loss.
• Expensive material.
• More susceptible to
external interference.
Electric Cables • Cheap material.
• Good resistance
to external interference.
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• Loss of transmission signal
over long distances.
• Vulnerable to electromagnetic interference.
Transmission Means
Wireless
It is a technology that don’t uses wires
to transmit data to another device.
Examples of wireless technologies:
–Bluetooth
– Infrared
– Wi-Fi
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Transmission Means
Bluetooth
Bluetooth is a communication protocol that allows the
connection via a radio frequency at short ranges,
between devices such as mobile phones,
laptops, computers, printers, digital cameras and game
consoles.
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Transmission Means
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Infrared
Another type of wireless transmission medium is based
on infrared light. Basically functions as the
communication system using optical fiber, but the beam
is transmitted through free space (light waves) instead
of fiberglass. The signal is converted to digital format
and transmitted through free space.
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Transmission Means
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Wi-Fi
Bluetooth is a communication protocol that allows the
connection via a radio frequency at short ranges,
between devices such as mobile phones,
laptops, computers, printers, digital cameras and game
consoles.
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Transmission Means
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Internet evolution
• 1960 - Introduction of modems that allowed the
connection of terminals to central computers.
• 1980- The need for transferring large files and
graphics led to the introduction of faster modems.
• 1990- The speeds increased to 56kbps modems.
• 2000- The high-speed services or broadband
becomes necessary.
• Use of transmission media (twisted pair, coaxial
cable, wireless or fiber optic).
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Modem
Switch
Router
Bridge
Modem
• Modem electronic equipment is one which has the
function, modulation and demodulation (through
which digital signals to recover the originally built).
• There are certain characteristics that distinguish each
other's modem:
• Bps: (Bytes per second) The more bps modem to allow
the faster the transmission and receipt of information.
• Voice/data: Transmission and reception of audio
signals. This is a mixture of the modem with the sound
card.
• Auto-answer: Allows the computer
to receive calls without the user.
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Internet connection equipment
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Modem
• There are two common types of modem:
• Broadband modems: The broadband modems are
connected to a cable or DSL (Digital Subscriber
Line) and provide access to high-speed Internet.
• Dial-up modems: Dial-up modems are connected
to the Internet using a telephone line, usually at
much lower than that of broadband modems.
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Switch
A switch is a device used in computer networks to
forward frames.
The switch functions are performed more quickly by
sending multiple packets simultaneously.
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Internet connection equipment
Bridge
Bridge is the term used in computing to describe a
device that connects two or more networks that use
different protocols or equal to two segments of the
same network using the protocol memo.
Bridges are used to interconnect two networks, such
as connection of a network of a building to another.
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Internet connection equipment
Router
The Router is a device that a packet switching network
information, is responsible for forwarding these from its
origin to its destination.
Routing is a function associated with the network layer in
a simple model of network programming, the OSI (Open
Systems Interconnection).
For home and office computers
that have a fast connection
to the Internet via cable, satellite
or DSL, the router can function
as a hardware firewall.
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Internet connection equipment
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Communication protocols
• In computer networks, a protocol is an objective set of
specifications that computers understand.
• Technically, it is a standard set of rules that
characterize the format, timing, sequence, and also
the detection of errors and failures in the transmission
of information between computers.
• Thus, two or more computers to communicate over a
network, must speak the same language, ie using the
same protocol.
• For communication to exist there must be at least one
channel, a transmitter and a receptor and ensure that
both have the option of using a common protocol.
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HTTP/HTTPS
FTP
POP
STMP
Communication protocols
• HTTP/HTTPS:
– The HyperText Transfer Protocol is an application
responsible for processing requests and responses
between client and server on the World Wide Web.
– He arose from the need to distribute information over
the Internet and that this distribution was possible was
necessary to create a standardized way of
communication between clients and Web servers and
understood by all computers connected to the Internet.
– The main idea is to create an HTTPS secure channel
over an insecure network. This ensures reasonable
protection of persons who perform illegal wiretaps
(called eavesdroppers) attacks and man-in-the-middle
(man-in-the-middle), since the encryption has been
properly used and that the server certificate is verified
and reliable.
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Communication protocols
• FTP
– File Transfer Protocol (FTP) is a standard network
protocol used to transfer files from one host to
another host over a TCP-based network, such as
the Internet.
– It is often used to upload web pages and other
documents from a private development machine
to a public web-hosting server.
– FTP is built on a client-server architecture and uses
separate control and data connections between
the client and the server.
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Communication protocols
• POP
– Post Office Protocol (POP) is an application-layer
Internet standard protocol used by local e-mail
clients to retrieve e-mail from a remote server over
a TCP/IP connection.
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Communication protocols
• STMP
– Simple Mail Transfer Protocol (SMTP) is the
standard protocol for sending e-mails over the
Internet.
– It is a relatively simple protocol, based on plain
text, where one or more recipients of a message
are specified (and in most cases verified to exist)
and then, the message transferred.
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