Class 07, Database, ESSENTIAL of (CS/IT/IS), for 1st level students of College of Computers, ESSENTIAL of (CS/IT/IS) class 07 (Networks)

1. SEIYUN UNIVERSITY
College of Applied Science – CS department
Instructor: Dr. Mazin Md. Alkathiri
Information technology Department
Faculty of Applied Sciences
Seiyun University – Yemen
Jan 2024

2. SEIYUN UNIVERSITY
College of Applied Science – CS department
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3. SEIYUN UNIVERSITY
College of Applied Science – CS department
• The term telecommunication means communication at
a distance.
• The word data refers to information presented in
whatever form is agreed upon by the parties creating
and using the data.
• Data communications are the exchange of data
between two devices via some form of transmission
medium such as a wire cable.
DATA COMMUNICATIONS
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4. SEIYUN UNIVERSITY
College of Applied Science – CS department
1.4
Figure 1.1 Components of a data communication system

5. SEIYUN UNIVERSITY
College of Applied Science – CS department
• A network is a set of devices (often referred to as
nodes) connected by communication links.
• A node can be a computer, printer, or any other device
capable of sending and/or receiving data generated by other
nodes on the network.
• A link can be a cable, air, optical fiber, or any medium
which can transport a signal carrying information.
NETWORKS
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6. SEIYUN UNIVERSITY
College of Applied Science – CS department
• Computer systems and peripherals are connected to
form a network. They provide numerous advantages:
• Resource sharing such as printers and storage devices
• Exchange of information by means of e-Mails and FTP
• Information sharing by using Web or Internet
• Interaction with other users using dynamic web pages
• IP phones
• Video conferences
• Parallel computing
• Instant messaging
Applications
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7. SEIYUN UNIVERSITY
College of Applied Science – CS department
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Network Criteria
• Performance
• Depends on Network Elements
• Measured in terms of Delay and Throughput
• Reliability
• Failure rate of network components
• Measured in terms of availability/robustness
• Security
• Data protection against corruption/loss of data due
to:
• Errors
• Malicious users

8. SEIYUN UNIVERSITY
College of Applied Science – CS department
• Type of Connection
• Point to Point - single transmitter and receiver
• Multipoint - multiple recipients of single transmission
• Physical Topology
• Connection of devices
• Type of transmission - unicast, mulitcast, broadcast
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Physical Structures

9. SEIYUN UNIVERSITY
College of Applied Science – CS department
• is a unicast connection. There is a dedicated link between an
individual pair of sender and receiver.
• The capacity of the entire channel is reserved only for the
transmission of the packet between the sender and receiver.
Types of connections:(A) point-to-point
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10. SEIYUN UNIVERSITY
College of Applied Science – CS department
• also called multidrop line configuration.
• a single link is shared by multiple devices.
• the channel capacity is shared temporarily by every
device connecting to the link.
Types of connections: (B) Multipoint
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11. SEIYUN UNIVERSITY
College of Applied Science – CS department
• A Network Topology is the arrangement with which
computer systems or network devices are connected to each
other.
• Topologies may define both physical and logical aspect of the
network.
Categories of topology
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12. SEIYUN UNIVERSITY
College of Applied Science – CS department
• In this type of topology, a host is connected to one or multiple
hosts.
• This topology has hosts in point-to-point connection with every
other host or may also have hosts which are in point-to-point
connection with few hosts only.
A fully connected mesh topology (five devices)
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13. SEIYUN UNIVERSITY
College of Applied Science – CS department
• All hosts in Star topology are connected to a central device,
known as hub device, using a point-to-point connection.
• That is, there exists a point to point connection between hosts and hub.
A star topology connecting four stations
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14. SEIYUN UNIVERSITY
College of Applied Science – CS department
• In case of Bus topology, all devices share single
communication line or cable.
• Bus topology may have problem while multiple hosts sending
data at the same time.
A bus topology connecting three stations
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15. SEIYUN UNIVERSITY
College of Applied Science – CS department
• In ring topology, each host machine connects to exactly two
other machines, creating a circular network structure.
• When one host tries to communicate or send message to a host
which is not adjacent to it, the data travels through all
intermediate hosts
A ring topology connecting six stations
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16. SEIYUN UNIVERSITY
College of Applied Science – CS department
• A network structure whose design contains more than one topology is said to
be hybrid topology.
A hybrid topology: a star backbone with three bus
networks
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17. SEIYUN UNIVERSITY
College of Applied Science – CS department
1.17
Categories of Networks
• Personal Area Network (PANs)
• Local Area Networks (LANs)
• Metropolitan Area Networks (MANs)
• Wide Area Networks (WANs)

18. SEIYUN UNIVERSITY
College of Applied Science – CS department
• A Personal Area Network (PAN) is smallest
network which is very personal to a user.
• This may include Bluetooth enabled devices or infra-
red enabled devices.
• PAN has connectivity range up to 10 meters.
• PAN may include wireless computer keyboard
and mouse, Bluetooth enabled headphones,
wireless printers and TV remotes.
Personal Area Network
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19. SEIYUN UNIVERSITY
College of Applied Science – CS department
• A computer network spanned inside a building and
operated under single administrative system is generally
termed as Local Area Network (LAN).
• Usually, LAN covers an organization’ offices, schools,
colleges or universities.
• Number of systems connected in LAN may vary from as
least as two to as much as 16 million.
• LAN provides a useful way of sharing the resources
between end users.
• The resources such as printers, file servers, scanners, and
internet are easily sharable among computers.
• LAN can be wired, wireless, or in both forms at once.
Local Area Network
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20. SEIYUN UNIVERSITY
College of Applied Science – CS department
LAN
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21. SEIYUN UNIVERSITY
College of Applied Science – CS department
• The Metropolitan Area Network (MAN) generally
expands throughout a city such as cable TV
network.
• Metro Ethernet is a service which is provided by
ISPs.
• This service enables its users to expand their Local
Area Networks. For example, MAN can help an
organization to connect all of its offices in a city.
• Backbone of MAN is high-capacity and high-
speed fiber optics.
Metropolitan Area Network
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22. SEIYUN UNIVERSITY
College of Applied Science – CS department
MAN
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23. SEIYUN UNIVERSITY
College of Applied Science – CS department
• As the name suggests, the Wide Area Network (WAN) covers a
wide area which may span across provinces and even a whole
country.
• Generally, telecommunication networks are Wide Area
Network.
• These networks provide connectivity to MANs and LANs.
• Since they are equipped with very high speed backbone, WANs use
very expensive network equipment.
Wide Area Network
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24. SEIYUN UNIVERSITY
College of Applied Science – CS department
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