Kingdom of Saudi Arabia
Prince Norah bint Abdul Rahman University
College of Computer Since and Information System
NET331
INTRODUCTION
T.Najah Al_Subaie
NET331
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Instructor:
T.Najah AL-Subaie
Course URL:
http://net331.wikispaces.com/
Text Book:
Behrouz A Frouzan ,”Data Communications and
Networking”, McGraw Hill, Fourth Edition.
Tanebaum, ”Computer Networks “, Prentic-Hall
Course Objectives
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Understanding the basics of computer Networks.
Understanding the types of network architectures
Understanding the principles of the layering
concepts.
Understanding the importance of networks in
different applications.
Grading
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2 Quizzes: 10%
Reading Summaries: 5%
Mid term : 20%
Home Works : 10%
Presentation: 5%
Final exam: 50%
Chapter 1
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Data communications.
Networks.
Protocols and Standard.
DATA COMMUNICATIONS
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Telecommunication

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Data

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Means communication at a distance.
Refers to information presented in whatever form is
agreed upon by the parties creating and using the data.
Data communications
 The
exchange of data between two devices via some
form of transmission medium such as a wire cable.
DATA COMMUNICATIONS

Data communication system has five components:
 Message
 Sender
 Receiver
 Transmission
 Protocol
medium
Components of Data Communication
Data Representation
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Text
Numbers
Images
Audio
Video
Data Flow
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Communication between two devices can be:
 Simplex
 The
communication is unidirectional; only one of the two
devices can transmit.
 Keyboard , monitor.
 Half
Duplex
 Each
station can both transmit and receive , but not at the
same time.
 Walkie-talkies phones.
 Full
Duplex
 Both
stations can transmit and receive simultaneously.
Data Flow
Network
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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.
Network

Distributed Processing
 Task

is divided among multiple computers.
Network Criteria
 Network
must meet a number of criteria:
 Performance
 Reliability
 Security
Network Criteria

Performance

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
Reliability
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Can be measured in many ways:
 Transmission time
 Response time.
Performance metrics:
 Throughput and delays.
 Throughput: network throughput is the average rate of
successful message delivery over a communication channel
Measured by frequency of failure, time required to recover from
a failure and other.
Security

Includes protecting data from unauthorized access.
Physical Structures
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Type of connection:
 Point
to point.
 Provides
a dedicated link between two devices.
 Entire capacity of the link is reserved for transmission
between those two devices.
 Example: the connection between the remote control and the
television control system.
 Multipoint.
 More
than two specific devices share a single link.
 Share the capacity of the channel
Types of connections: point-to-point
and multipoint
Physical Structures
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Physical topology
 Refers
to the way in which a network is laid out
physically.

Four basic topologies:
 Mesh
 Star
 Bus
 ring
Categories of Topology
Mesh
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Every device has a dedicated point to point link to
every other device.
For a network with n nodes. The number of physical
links is n(n-1)/2
Pros
Cons
A fully connected mesh topology (five
devices)
Star Topology
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Each device has a dedicated point to point link only
to a central controller called a hub.
Number of links:
Pros.
Cons.
A star topology connecting (four
stations)
Bus Topology
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The devices are connected to one long cable.
Pros.
Cons.
A bus topology connecting (three
stations)
Ring Topology
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Each device has a dedicated point to point
connection with only the two devices on either side
of it.
Pros.
Cons.
A ring topology connecting six
stations
A hybrid topology: a star backbone
with three bus networks
Network Models
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Network models are defined by a standards.
Standards are needed to allow heterogeneous
devices to communicate with each other.
Two standards for network models:
 OSI
(Open System Interconnection) Model.
 Internet Model.
Network Categories
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Categories of the networks based on their sizes:

Local Area Network
Privately owned and links the devices in a single office, building.
 Size : few kilometers.
 Usually used to share resources between personal computers.

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Wide Area Network
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Metropolitan Area Network

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Provides long distance transmission of information. (e.g. country)
A network with a size between a LAN and WAN. (e.g. city)
Internet

Two or more connected networks.
Protocols and Standards
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Protocols:
Set of rules that govern data communications.
Standards:
Agreement upon rules.
Homework

Summarizing Chapter 1 in the text book ( Data
communication and networking) .