DCCN: Course objectives and Course Outcomes

 This course introduces students to the fundamental concepts of data communication and computer networks. It covers the basic components of network systems, transmission media, multiplexing, switching technologies, error detection and correction techniques, medium access control protocols, and network topologies. The course also explores Internet protocols, transport layer mechanisms, and application layer functions, providing students with a comprehensive understanding of how data is transmitted and processed across networks.

Course Objectives:

1. To introduce students to the basic components and concepts of data communication and networking.
2. To provide a comprehensive understanding of transmission media, multiplexing and switching.
3. To explain error detection and correction techniques, and medium access control.
4. To explain the functions and protocols associated with Internet layer, Transport and Application layers.
5. To understand the various network topologies and network devices.

Course Outcomes:

After successful completion of this course the student will be able:

1. To understand the fundamentals of data communication and computer networks.
2. To understand transmission media, multiplexing and switching.
3. To gain the ability to implement and analyze error detection and correction techniques and understand medium access control methods.
4. To be capable of describing Internet and Transport layer protocols.
5. To identify and explain the various components and topologies of data communication systems

DCCN:BOOKs

 book

Data-Communications-and-Networking-By-Behrouz-A.Forouzan

Computer Network (Andrew S Tanenbaum)

Type of connection

 Two types of connections

a. Point-to-point

b. Multipoint

In point-to-point connection the two devices are connected by a dedicated link. The entire capacity of

the link is reserved for transmission between those two devices.

A multipoint (also known as multidrop) connection is one in which more than two specific devices share

a single link. The capacity of the channel is shared either spatially or temporally.

Computer Network (Difination)

 Network: Definition:

• A network is set of devices (nodes) connected by communication links (media)
• A node can be a computer, printer or other device capable of sending and/or receiving data
• Link connecting the devices are often called communication channels
• Most network use distributed processing.

Distributed Processing Networks use distributed processing in which a task divided among multiple computers. Separate computers handle a subset instead of a single machine responsible for all aspects of a process.

Performance Performance can be measured in terms of transit time, response time, number of users, type of transmission medium, and capabilities of the connected hardware and the efficiency of the software.

Transit time The time required for a message to travel from one device to another.

Response time The time spent between an inquiry and a response

Reliability It is measured by the frequency of failure and time required to recover from a failure.

Security Network security is protecting data from unauthorized access.

Internetwork

 Connection of two or more networks by the use of internetworking devices which include routers

and gateways

 Internet is a generic term used to mean an interconnection of networks

 The Internet is the name of a specific worldwide network.

Notes on Protocols in Computer Networks

 

Definition of a Protocol

In computer networks, communication occurs between entities (devices, applications, or systems) that exchange information. For successful communication, entities must follow a protocol—a set of rules governing data exchange. A protocol defines:

• What is communicated (data format).

• How it is communicated (transmission method).

• When it is communicated (synchronization and speed).

Key Elements of a Protocol

1. Syntax

   • Refers to the structure or format of the data.

   • Example: A protocol may define:

     • First 8 bits = Sender’s address.

     • Next 8 bits = Receiver’s address.

     • Remaining bits = Actual message.

2. Semantics

   • Refers to the meaning of each part of the data.

   • Example:

     • Does an address field indicate the destination or a routing path?

     • What does a specific bit pattern represent (e.g., error code, control signal)?

3. Timing

   • Ensures synchronization and speed matching between sender and receiver.

   • Includes:

     • When data should be sent (e.g., flow control).

     • How fast data can be transmitted (e.g., matching sender/receiver speeds).

   • Example: If a sender transmits at 100 Mbps but the receiver processes at 1 Mbps, data loss occurs due to overload.

Importance of Protocols

• Enable standardized communication between different systems.

• Ensure reliable, efficient, and error-free data transfer.

• Facilitate interoperability between devices from different manufacturers.

Examples of Protocols

• HTTP (Hypertext Transfer Protocol) – Web communication.

• TCP/IP (Transmission Control Protocol/Internet Protocol) – Internet data transfer.

• Ethernet – LAN communication.

Conclusion

Protocols are essential for structured and efficient network communication, ensuring that devices interpret data correctly and synchronize transmissions effectively.

Client-Server Architecture

 Definition: Client-Server Architecture is a network architecture where multiple clients (users) request and receive services from a centralized server. The server hosts, manages, and delivers resources or services to clients over a network.

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Key Components:

• Client:

  • A device or software application that requests services or resources from the server.

  • Examples: Web browsers, mobile apps, desktop apps.

• Server:

  • A powerful system or software that provides services or resources to clients.

  • Examples: Web servers, database servers, file servers.

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Diagram:

          +-----------+         Request         +-----------+
          |           | ---------------------> |           |
          |  Client   |                        |   Server  |
          | (Browser) | <--------------------- | (Web/App) |
          +-----------+        Response        +-----------+
                |                                     |
          +-----------+                        +-----------+
          |  Client   |                        | Database  |
          | (Mobile)  |                        |  Server   |
          +-----------+                        +-----------+

You can imagine:

• Clients send requests to the server (like asking for a webpage).

• Server processes the request and sends a response back (like returning the webpage).

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Advantages:

• Centralized control.

• Easier maintenance and security.

• Scalability (add more clients easily).

Disadvantages:

• Server bottlenecks if overloaded.

• Single point of failure (if server goes down).

Data representation

Data Representation

Information can be in any form such as text, numbers, images, audio, and video.

1. Text

• Text is represented as a bit pattern.

• The number of bits in a pattern depends on the number of symbols in that language.

• Code is the set of bit patterns designed to represent text symbols.

ASCII (American Standard Code for Information Interchange)

• Developed by ANSI (American National Standards Institute).

• Uses 7 bits for each symbol.

Extended ASCII

• To make the size 1 byte (8 bits), an extra 0 is added to the left of the ASCII bit patterns.

• This does not change the value of the pattern.

Unicode

• Used to represent symbols or text in any language.

• Uses 32 bits to represent characters.

ISO (International Organization for Standardization)

• Designed a 32-bit pattern.

• Can represent up to 4,294,967,296 symbols.

2. Numbers

• Represented using bit patterns.

• Instead of ASCII, numbers are directly converted to binary.

3. Images

• Represented by bit patterns.

• An image is divided into a matrix of pixels (smallest element of an image).

• Each pixel is assigned a bit pattern.

• The size and value of the pattern depend on the image.

4. Audio

• Audio refers to the recording or broadcasting of sound or music.

• It is continuous, not discrete like text, numbers, or images.

5. Video

• Video refers to the recording or broadcasting of pictures or movies.

• It can be:

  • A continuous entity (like live streaming).

  • A combination of images (frames in a video).

Standards and Standard Organizations

 

Network Standards Organizations

Introduction to Standards

Standards are essential to ensure compatibility and interoperability between different systems and devices. They ensure that products from different manufacturers can work together as expected.

Why We Need Standards

• Create and maintain an open and competitive market for equipment manufacturers
• Guarantee national and international interoperability of data, telecommunication technology and processes
• Provide fixed quality and products to customers
• Allow products to be reused in different contexts
• Aid the design and implementation of ideas
• Provide guidelines to manufacturers, vendors, government agencies and other service providers to ensure interconnectivity

Types of Data Communication Standards

De facto (from the fact)

• Standards that have not been approved by an organized body
• Adopted as standards through widespread use
• Often established originally by manufacturers to define the functionality of a new product or technology

De jure (by law)

• Standards that have been legislated by an officially recognized body

Standards are developed through the cooperation of standards creation committees, forums, and government regulatory agencies.

Standards Creation Committees

ITU (International Telecommunications Union, formerly CCITT)

• Establishes standards for telecommunication in general and data systems in particular

ISO (International Standards Organization)

• Active in developing cooperation in scientific, technological, and economic activities
• Develops standards for many aspects of networking

ANSI (American National Standards Institute)

• Private nonprofit corporation affiliated with the U.S. federal government

IEEE (Institute of Electrical and Electronics Engineers)

• Aims to advance theory, creativity, and product quality in electrical engineering, electronics, radio, and related branches of engineering
• Oversees development and adoption of international standards for computing and communications
• Creates standards for wireless networking and networking hardware
• Website: http://standards.ieee.org/

EIA (Electronic Industries Association)

• Nonprofit organization devoted to promoting electronics manufacturing concerns
• Activities include public awareness education and lobbying efforts in addition to standards development
• Made significant contributions by defining physical connection interfaces and electronic signaling specifications for data communication

IETF (Internet Engineering Task Force)

• Develops standards specifically for the Internet

Forums

• Work with universities and users to test, evaluate, and standardize new technologies
• Speed acceptance and use of technologies in the telecommunications community
• It presents their conclusions to standard bodies.

Regulatory Agencies

• Purpose is to protect the public interest by regulating radio, television and wire/cable communications
• Have authority over interstate and international commerce as it relates to communication

Internet Standards

• Thoroughly tested specifications that are useful to and adhered to by those who work with the internet
• Formalized regulations that must be followed
• A specification begins as an Internet draft and may attain Internet standard status
• An Internet draft is a working document that may be published as Request for Comment (RFC)
• RFCs are edited, assigned a number, and made available to all interested parties

Components of Data Communication

 Q. What are the components of Data communication?

The following are the key components in a data communication system:

1. Message Message is the information to be communicated by the sender to the receiver.
2. Sender The sender is any device that is capable of sending the data (message).
3. Receiver The receiver is a device that the sender wants to communicate the data (message).
4. Transmission Medium It is the path by which the message travels from sender to receiver. It can be wired or wireless and many subtypes in both.
5. Protocol
   • It is an agreed upon set of rules used by the sender and receiver to communicate data.
   • A protocol is a set of rules that governs data communication.
   • A Protocol is a necessity in data communications without which the communicating entities are like two persons trying to talk to each other in a different language without knowing the other language.

These five components form the foundation of any data communication system. Each component must function properly for successful data transmission to occur. The transmission medium provides the physical or wireless path, while protocols ensure that both sender and receiver understand how to format, send, receive, and interpret the messages being exchanged.

Extra Question: Explain Protocol

Key Components of Data Communication

 

Components of Data Communication

The following are the key components in a data communication system:

1. Message Message is the information to be communicated by the sender to the receiver.
2. Sender The sender is any device that is capable of sending the data (message).
3. Receiver The receiver is a device that the sender wants to communicate the data (message).
4. Transmission Medium It is the path by which the message travels from sender to receiver. It can be wired or wireless and many subtypes in both.
5. Protocol
   • It is an agreed upon set of rules used by the sender and receiver to communicate data.
   • A protocol is a set of rules that governs data communication.
   • A Protocol is a necessity in data communications without which the communicating entities are like two persons trying to talk to each other in a different language without knowing the other language.

These five components form the foundation of any data communication system. Each component must function properly for successful data transmission to occur. The transmission medium provides the physical or wireless path, while protocols ensure that both sender and receiver understand how to format, send, receive, and interpret the messages being exchanged.

Extra Question

Q. Explain Protocol

Process of Data Communication

Q. 1 What is meant by Data Communication and explain its characteristics?

Q. 2 Define Data Communication.

1. Data communication is the process of exchanging information or data between two or more devices through a transmission medium.

2. Data communication forms the backbone of all computer networks and is essential for technologies like the internet, mobile phones, cloud computing, and virtually all digital services we use today.

Process of Data Communication

The basic process follows these steps:

1. The sender generates the message and converts it into a transmittable signal
2. The signal travels through the transmission medium
3. The receiver receives the signal and converts it back into an understandable message
4. The receiver acknowledges receipt if required by the protocol

Characteristics of Data Communication

The effectiveness of any data communications system depends upon the following four fundamental characteristics:

1. Delivery: The data should be delivered to the correct destination and correct user.
2. Accuracy: The communication system should deliver the data accurately, without introducing any errors. The data may get corrupted during transmission affecting the accuracy of the delivered data.
3. Timeliness: Audio and Video data has to be delivered in a timely manner without any delay; such a data delivery is called real time transmission of data.
4. Jitter: It is the variation in the packet arrival time. Uneven Jitter may affect the timeliness of data being transmitted.

Characteristics of Effective Data Communication

• Delivery: The system must deliver data to the correct destination
• Accuracy: The system must deliver data accurately, without alterations or errors
• Timeliness: The system must deliver data in a timely manner to be useful
• Jitter: Refers to the variation in packet arrival time, which should be minimized

Data and Information

 Data and information are related concepts but have distinct meanings:

Data

• Raw, unorganized facts, figures, or symbols
• Without context or interpretation
• Examples: numbers, text strings, dates, or binary code
• On its own, data typically lacks meaning or usefulness

Information

• Data that has been processed, organized, structured, or presented
• Has context, relevance, and purpose
• Provides meaning and value to the recipient
• Examples: reports, charts, tables with labeled data, or analyzed statistics

The key difference is that information is data that has been given context and meaning through processing, organization, or analysis. Data becomes information when it's transformed to be useful for decision-making or understanding.

For example, "98.6" is just a piece of data, but "The patient's temperature is 98.6°F, which is normal" is information because it provides context and meaning.

Here is the difference between Data and Information in a tabular format:

Data	Information
Derived from the Latin word "Datum"	Derived from the word "Informare"
Data is a raw fact	Processed form of data
May or may not be meaningful	Always meaningful
Input to any system may be treated as data	Output after processing data is information
Understanding is difficult	Understanding is easy
Data may not be in order	Information should be in order
Example: Survey data	Example: Census report