Computer Networking Concepts

Computer Networking Concepts

• Computer networking connects computers to share resources like browsing the web, sending emails, and sharing files.
• Organizations use networks for tasks like word processing, scientific computing, and control processing.
• Networks are categorized by geographical scope.

Network Categories

• Personal Area Network (PAN): Smallest network, connects compatible personal devices like wireless earphones to smartphones or computers to printers.
• Local Area Network (LAN): Connects devices within a building or a limited area (company, house, etc.), sharing resources.
• Campus Area Network (CAN): Connects multiple buildings on a campus (university, organization), combining LANs.
• Metropolitan Area Network (MAN): Connects buildings across a city, wirelessly connecting elements (traffic lights, parking meters).
• Wide Area Network (WAN): Largest network, spans cities, provinces, or countries, composed of LANs and MANs.

Network Architecture

• A diagram showing the structure of network devices, aiming to meet client connectivity needs.
• Common network types include:
  • Access networks: Connects devices and users within a campus or branch.
  • Data center networks: Links multiple servers and applications for user access.
  • Wide Area Networks (WANs): Connects users to programs and services (e.g., hospital employees accessing health applications).
• Network architecture diagrams represent network structure and connected devices.

The Open Systems Interconnection (OSI) Model

• A seven-layered model for interlinking different network types.
• Defines standards for networking to ensure compatibility among different network components and software.
• Layers from physical connection to application interface.
• Layers define network functions from physical to application level.

OSI Model Layers

• Physical Layer: Electrical and mechanical connections to the network.
• Data Link Layer: Handles error recovery, flow control, and sequencing for terminal connections. This layer defines MAC addresses.
• Network Layer: Network controller that receives outgoing messages. Combines messages and segments into packets with routing information.
• Transport Layer: Responsible for end-to-end delivery of messages between devices, ensuring message integrity, and segmenting and reassembling packets.
• Session Layer: Provides control for starting, managing, and ending connections.
• Presentation Layer: Accepts and structures messages, converting data, and handling compression and encryption.
• Application Layer: Interacts with application programs, handling requests and identifying information to support them.

Network Types and Devices

• Wired Networks: Use cabling and connectors for network connection.
• Wireless Networks: Use radio signals for connections.
• Wired Network Devices:
  • LAN Ethernet Cable: Connects devices within a local area network, limited by length and quality.
  • Hub: Interconnects network devices, causing broadcast of data to all connected devices.
  • Switch: Creates direct connections from sender to receiver, preventing broadcast of data.
  • Cable Modem: Connects a home network (broadband) to internet service providers (ISP).
  • Servers: Provide resources, data, and programs to other computers or clients on a network.
  • Firewall: Monitors and secures network traffic to enforce security policies.
• Wireless Network Devices:
  • Wireless Access Point: Connects devices to wired LANs, providing wireless connection.
  • Wireless Router: Combines a router, switch, and wireless access point, enabling wireless LAN connection to an ISP.

Network Topologies

• Point-to-Point: Simplest, connects two devices directly.
• Token Ring: Deterministic transmission, each station has time intervals to transmit.
• Bus: Computers sharing a common transmission medium (coaxial cable), allowing all devices to see each other's transmissions.
• Star: Devices connect to a central switch or hub, common in modern networks.
• Mesh: Networking devices directly connected, with various paths between devices (fully or partially meshed).