ITPC 105 Reviewer

ITPC 105 – Networking 1

Module 1: Computer Networks and Data Communications

Lesson 1: Introduction and History of Computer Networks

• Definition of Computer Network: A collection of interconnected computers and devices sharing information and resources.

Types of Computer Networks

1. Local Area Network (LAN):

   • Privately owned.

   • Links devices in a single office or campus (up to a few kilometers in size).

2. Metropolitan Area Network (MAN):

   • Extends over an entire city.

   • Example: Cable television networks.

3. Wide Area Network (WAN):

   • Spans regional, national, or global areas.

Key Components of Networks

• Computers/Nodes: Devices interconnected in a network.

• Networking Hardware:

  • Network adapter cards: Provide physical connections for computers.

  • Network hub/switch: Connection points for network cables. Hubs connect multiple PCs; switches connect segments intelligently.

  • Network cables: Unshielded twisted pair (UTP) for physical connections.

  • Wireless technology: Uses radio communications instead of cables.

• Networking Software: Enables communication among connected computers.

Networking History

• Early Communication: Began with Samuel Morse and the telegraph in 1844.

• Inventions:

  • Alexander Graham Bell: Telephone.

  • Emile Baudot: Developed printing telegraph.

• Regulatory Changes:

  • 1985: Bell Telephone Company (now AT&T) owned the telephone network.

  • 1975: FCC allowed devices that meet specifications to attach to phone systems.

Lesson 2: Importance of Computer Networks

1. File Sharing: Quick and easy file transfers.

2. Security: Password-protected directories limit access to authorized users.

3. Resource Sharing: Shared access to printers, fax machines, etc.

4. Communication: Network users can communicate via electronic mail.

5. Flexible Access: Access files from anywhere in the network.

6. Workgroup Computing: Concurrent document collaboration using workgroup software.

7. Error Reduction: Working from a single source reduces errors and promotes consistency.

Goals of Computer Networks

1. Overcoming Geographic Separation: Enables communication across cities and countries.

2. Information Sharing: Access to distributed databases.

3. Supporting Distributed Processing: Process data across various locations.

Advantages of Wireless Networking

• Pros: Mobility, ease of access, no cables.

• Cons: Security concerns and potential radio interference.

Lesson 3: Data Communication

• Definition: Exchange of data (0s and 1s) between devices via transmission media.

Characteristics of Data Communication

• Delivery: Data must reach the correct destination.

• Accuracy: Data must remain unchanged in transmission.

• Timeliness: Essential for applications requiring real-time data (e.g., video calls).

• Jitter: Variation in packet arrival time.

Components of Data Communication

1. Message: Information to be communicated.

2. Sender: Device transmitting the data.

3. Receiver: Device receiving the message.

4. Medium: Physical path for data transmission (cables, radio waves).

5. Protocol: Rules governing data communication.

System Transmission Modes

• Simplex: One-way transmission.

• Half-duplex: Two-way transmission but not simultaneous.

• Full-duplex: Simultaneous two-way transmission.

Elements of Data Communication System

1. Sender/Transmitter: Device initiating communication.

2. Message: Data or information for transmission.

3. Medium/Channel: Path for data transfer.

4. Receiver: Device receiving messages.

5. Encoder/Decoder: Converts signals between formats.

Lesson 4: Network Hardware Essentials

• Definition of Networking Hardware: Devices needed for communication between computers on a network.

• Common Hardware:

  1. Repeater: Regenerates signals over long distances.

  2. Hub: Multi-port device connecting multiple computers.

  3. Switch: Intelligent device managing traffic between ports.

  4. Router: Forwards data packets between networks.

  5. Network Bridge: Connects multiple networks as a single network.

  6. Wireless Access Points (WAP): Connects Wi-Fi devices to a wired network.

  7. Network Interface Controller (NIC): Physical connection for devices on a wired network. Contains a MAC Address for identification.

MODULE II

Network Architecture, Standards, Protocols, and Topologies

Lesson 1: Network Architecture

• Definition: Framework outlining how computers and devices are arranged and communicate.

Types of Network Architecture

1. Peer-to-Peer (P2P): Each node acts as both client and server. Resources are shared equally.

2. Client/Server: Central server manages resources and services for clients.

Differentiation of Clients

• Thick Client: Performs data processing with minimal server dependency.

• Thin Client: Relies heavily on the server for processing.

• Hybrid Client: Combines features of both thick and thin clients.

Switching Techniques

1. Circuit Switching: Establishes a dedicated connection before data transmission.

2. Message Switching: Stores messages before forwarding them.

3. Packet Switching: Breaks data into packets for transmission.

Lesson 2: Network Protocols

• Definition: Rules governing data exchange across networks.

Application Layer Protocols

• DHCP: Automates IP address assignment.

• DNS: Maps host names to IP addresses.

• FTP: Enables file sharing over networks.

• HTTP: Protocol for web content transfer.

• IMAP/IMAP4: Manages email access.

• POP3: Downloads emails to local clients.

• SMTP: Sends email.

• Telnet: Remote communication protocol.

• SNMP: Manages network devices.

Transport/Network Layers and Protocols

• TCP: Provides reliable data transmission.

• UDP: Offers an unreliable message service.

• IP/IPv6: Addresses and routes packets.

• ICMP: Sends error messages and operational info.

Network Topologies

• Definition: Schematic description of network arrangements.

Types of Network Topologies

1. Bus Topology: All devices connected along a single cable.

2. Ring Topology: Nodes arranged in a circle.

3. Star Topology: All devices connected to a central hub.

4. Mesh Topology: All nodes interconnected either fully or partially.

5. Tree Topology: Hierarchical arrangement with a root node.

6. Hybrid Topology: Combination of two or more types.

Switching and the OSI Model

• Multiplexing: Allows multiple data streams over a single channel (MUX and DEMUX).

Types of Multiplexing

1. Frequency Division Multiplexing (FDM): Combines analog signals.

2. Wavelength Division Multiplexing (WDM): For high data rates over fiber-optic cables.

3. Time Division Multiplexing (TDM): Divides time for data transmission.

4. Code Division Multiplexing (CDM): Uses unique codes for simultaneous data transmission.

OSI Model Layers

1. Physical Layer: Activates physical link and translates bits.

2. Data Link Layer: Manages frame creation and communication through hardware.

3. Network Layer: Determines routing and addressing.

4. Transport Layer: Ensures reliable data delivery and error management.

5. Session Layer: Manages sessions between devices.

6. Presentation Layer: Formats data for transfer.

7. Application Layer: Supports user applications and services.