In-Depth Notes on Wired and Wireless Local Area Networks

Why Use a LAN?

  • Information Sharing:

    • Enhances decision-making.
    • Reduces data duplication and inconsistency.

  • Resource Sharing:

    • Allows many clients to share expensive devices such as printers and scanners.

  • Software Sharing:

    • Software can be purchased per-seat; financial savings on licenses.
    • Systems like Office 365 use cloud storage, simplifying maintenance and upgrades.

  • Device Management:

    • Software updates and configuration become easier and more uniform.

LAN Components

  1. Clients:
    • Devices requesting information from servers.
  2. Servers:
    • Provide information or services to clients.
  3. Network Interface Cards (NICs):
    • Also known as network cards or adapters; operate at layers 1 and 2 of the OSI model.
    • Commonly integrated into motherboards; Ethernet NICs contain a unique MAC address.
  4. Network Cables:
    • Include various types (Category 3, 5, 5e, 6/6a, and fiber optic) with varying maximum data rates.
  5. Hubs/Switches/Access Points:
    • Connect various devices and can strengthen signals.
  6. Software:
    • Network Operating Systems (NOS) like Novell NetWare, Microsoft Windows Server, and Linux; crucial for network management.

Wired Ethernet

  • Based on IEEE 802.3 standards; predominant in LANs today.
  • Originally developed at Xerox PARC and standardized by a consortium (DIX).
  • Topologies:
    • Logical Topology: Conceptual operation of the network.
    • Physical Topology: Physical arrangement of devices.
Hub-based Ethernet
  • Known as shared or traditional Ethernet.
  • Logical bus topology: Devices receive all frames.
  • Physical star topology: Central hub connects all devices.
Switch-based Ethernet
  • Logical star topology: Only the intended destination receives the frame.
  • Switches manage MAC addresses and use forwarding tables to direct traffic.
  • Breaks collision domains for improved performance.

Switching Modes

  1. Store and Forward Switching:
    • Complete frame received before transmission; reduces errors but increases latency.
  2. Cut-Through Switching:
    • Transmission starts after reading destination address; lower latency, higher error possibility.
  3. Fragment-Free Switching:
    • Transmits after first 64 bytes are checked for errors; a balance of the first two modes.

Media Access Control

  • CSMA/CD (Carrier Sense Multiple Access with Collision Detection):
    • Devices check for transmission before sending signals to avoid collisions.

Wireless Ethernet

  • Known as Wi-Fi (Wireless Fidelity), defined by IEEE 802.11 standards.
  • Benefits include mobility and ease of installation.
Components of Wireless Ethernet
  • Access Points (APs):
    • Connect wireless clients to the wired network using radio waves.
    • Can use Power over Ethernet (PoE) for installations.
  • Topology:
    • Physical star; logical bus with media access controlled via CSMA/CA.

Wi-Fi Types and Specifications

  • 802.11 standards defined various enhancements over the years, from 802.11a in 1999 to 802.11ax in 2019, with increasing transmission speeds.
Security Protocols
  • WEP: Outdated and insecure.
  • WPA/WPA2: Recommended for stronger security against unauthorized access.

LAN Design Considerations

  • Best practice: wired LAN as primary and wireless as supplementary.
  • Assess site coverage, interference, and required equipment through a site survey.
  • LAN requirements can vary significantly based on specific functionality and performance needs.

Improving LAN Performance

  • Identifying Bottlenecks: Major obstacles in data flow can include server or circuit limitations.
  • Network Management Techniques:
    • Upgrade server hardware/software.
    • Enhance client devices or networking hardware.
    • Optimize circuit speed and add channels or access points as needed.
    • Promote off-peak usage to manage demand effectively.

Implications for Management

  • The evolution of LAN equipment into commonplace commodities.
  • Rise in demand for wireless in SOHO environments, driven by increased device connectivity and IoT influences on LAN design.