Unit 2: Data Communication and Networking (15 Hours)

Unit 2: Data Communication and Networking (15 Hours)

2.1 Basic Elements of Communication System

A communication system consists of several basic elements:

• Sender: The device or person who initiates the communication process.
• Message: The information that is being communicated.
• Medium: The channel through which the message is transmitted (e.g., wired, wireless).
• Receiver: The device or person that receives and interprets the message.
• Feedback: The response from the receiver back to the sender, which helps to confirm the message has been received and understood.

2.2 Concept of Communication System

A communication system is a collection of hardware and software components that facilitate the exchange of information between users. It encompasses various processes, including the transmission of data, encoding, modulation, and error detection.

2.3 Block Diagram of Communication System/Model

A typical block diagram of a communication system includes the following components:

• Information Source: Generates the message.
• Transmitter: Encodes and modulates the message for transmission.
• Channel: The medium through which the message travels (e.g., air, cable).
• Receiver: Demodulates and decodes the message.
• Destination: The final user or device that receives the information.

2.4 Elements of Data Communication/Transmission

• Data: The information to be communicated.
• Transmission Medium: The physical path through which data is transmitted (e.g., copper wires, fiber optics).
• Protocol: A set of rules governing data transmission (e.g., TCP/IP, HTTP).
• Modulation: The process of converting digital data into analog signals for transmission.

2.5 Simplex, Half Duplex, and Full Duplex Communication Modes

• Simplex: Communication is one-way only. For example, a keyboard sends data to a computer but cannot receive data back.
• Half Duplex: Communication is two-way, but not simultaneous. For example, walkie-talkies allow one person to talk while the other listens.
• Full Duplex: Communication is two-way and simultaneous. For example, a telephone conversation allows both parties to speak and listen at the same time.

2.6 Concept of LAN and WAN

• LAN (Local Area Network): A network that covers a small geographic area, such as a home, office, or campus. LANs typically have high data transfer rates and low latency.
• WAN (Wide Area Network): A network that covers a large geographic area, such as a city, country, or global connections. WANs often use leased telecommunication lines and have lower data transfer rates compared to LANs.

2.7 Transmission Medium: Guided and Unguided

• Guided Transmission Media: Physical media that guide the signal along a specific path. Examples include twisted pair cables, coaxial cables, and fiber optic cables.
• Unguided Transmission Media: Wireless media that transmit signals through the air. Examples include radio waves, microwaves, and infrared signals.

2.8 Transmission Impairments Terminology

• Jitter: Variability in packet arrival times, leading to uneven data transmission.
• Singing: Interference caused by overlapping frequencies.
• Echo: A delayed reflection of the transmitted signal that can cause confusion in communication.
• Crosstalk: Interference from adjacent channels or wires.
• Distortion: Alteration of the original signal, leading to inaccuracies.
• Noise: Unwanted electrical signals that interfere with data transmission.
• Bandwidth: The maximum data transfer rate of a network, usually measured in bits per second (bps).
• Number of Receivers: The number of devices that can receive the transmitted data, affecting network performance.

2.9 Basic Concept of Network Architecture: Client-Server and Peer-to-Peer

• Client-Server Architecture: A centralized model where a server provides resources or services to multiple clients. Clients request services, and the server responds. This architecture is common in web applications.
• Peer-to-Peer Architecture: A decentralized model where each device (peer) acts as both a client and a server. Peers can share resources without a centralized server, commonly used in file-sharing networks.

2.10 Some Basic Terms and Tools Used in Computer Network

• IP Address: A unique identifier assigned to each device on a network, allowing for communication between devices.
• Subnet Mask: A number that defines the network and host portions of an IP address, used to determine which part of the address refers to the network and which part refers to the host.
• Gateway: A device that connects two different networks, serving as a translator between different protocols.
• MAC Address: A hardware address that uniquely identifies each device on a local network.
• Internet: A global network of interconnected computers that communicate using standardized protocols.
• Intranet: A private network that uses internet technologies to share information within an organization.
• Extranet: A controlled private network allowing access to specific outsiders, such as partners or suppliers.

2.11 Network Tools: Packet Tracer, Remote Login

• Packet Tracer: A simulation tool used for designing and troubleshooting network topologies, providing a visual representation of network configurations and protocols.
• Remote Login: A method that allows users to access and control a computer or network device remotely, using protocols like SSH (Secure Shell) or Telnet.

2.12 Network Connecting Devices: NIC, Modem, Router, Switch

• NIC (Network Interface Card): A hardware component that allows a device to connect to a network, either wired or wireless.
• Modem: A device that modulates and demodulates signals for data transmission over telephone lines or cable systems, allowing access to the internet.
• Router: A device that routes data packets between different networks, determining the best path for data transmission.
• Switch: A device that connects multiple devices on a local area network, allowing them to communicate with each other.

2.13 Network Topologies: Bus, Ring, and Star Topology

• Bus Topology: All devices are connected to a single central cable (the bus). It is easy to set up but can lead to performance issues if the bus fails.
• Ring Topology: Each device is connected to two others, forming a circular data path. Data travels in one direction, which can simplify data handling but can be disrupted if one device fails.
• Star Topology: All devices are connected to a central hub or switch. It is easy to manage and troubleshoot but can be affected if the hub fails.

2.14 Basic Concept OSI Reference Model

• The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven layers:
  1. Physical Layer: Concerned with the transmission of raw data bits over a physical medium.
  2. Data Link Layer: Provides node-to-node data transfer and error detection/correction.
  3. Network Layer: Manages routing and forwarding of data packets.
  4. Transport Layer: Ensures complete data transfer and error recovery.
  5. Session Layer: Manages sessions and controls dialog between applications.
  6. Presentation Layer: Translates data formats and encryption.
  7. Application Layer: Provides network services to end-users and applications.

2.15 Internet Protocol Addressing

• Internet Protocol Addressing involves assigning unique addresses to devices on a network, enabling them to communicate. There are two main versions:
  • IPv4: Uses 32-bit addresses, providing approximately 4.3 billion unique addresses.
  • IPv6: Uses 128-bit addresses, allowing for a vastly larger address space to accommodate the growing number of devices connected to the internet.