Local Area Networks (LAN) and High-Speed Networks: Fundamentals

Chapter 1: Local Area Network (LAN) Fundamentals

A local area network (LAN) includes the components, both software and hardware, that enable microcomputers, PCs, and peripherals within a limited geographical area to communicate with each other. LANs also facilitate the distribution and sharing of all system resources between different units.

Key Characteristics of a Local Area Network

• Limited geographical area
• High transmission speed (from 1 Mbit/s to 1 Gbit/s)
• Low error rate
• Entire network is owned and managed by the user

These LANs can be interconnected in various ways using repeaters, bridges, gateways, routers, or switches.

Local Area Network Objectives

• Allow secure communication at a reasonable cost
• Be structured in levels, allowing changes by level without affecting the rest of the network
• Ensure compatibility of products designed and manufactured by different companies
• Allow for better organization of the company

Following the philosophy of the ISO OSI model, communication between processes is performed at the same level.

Functional Objectives of Local Area Networks

• Data transparency: Upper levels should be free to use any combination of bits or characters
• Allow the addition or deletion of nodes easily and quickly
• Allow the use of adequate physical resources, physical environment, bandwidth, etc.

Advantages of Local Area Networks

• Distribution of peripherals (expensive resources)
• Distribution of information (mass storage)
• Email
• Fast transfer of information
• Ability to work in groups

Chapter 7: High-Speed Networks

High-speed networks incorporate the latest advances in equipment and systems.

Fast Ethernet

100-BASE-T Fast Ethernet operates at a speed of 100 Mbps and can use unshielded twisted pair (UTP), shielded twisted pair (STP), or fiber optic cable.

Features of Fast Ethernet

• Speed of 100 Mbit/s
• MAC sublayer identical to that of 10-BASE-T
• Frame format identical to that of 10-BASE-T
• Same wiring as 10-BASE-T (meeting EIA/TIA 568 standards)
• Greater consistency in error handling compared to 10-BASE-T

Note that Fast Ethernet does not work with coaxial cable and requires adapters that incorporate connections for RJ45 or fiber optics.

Gigabit Ethernet

Gigabit Ethernet is an extension of the IEEE 802.3 standard, increasing the speed of Fast Ethernet tenfold to 1 Gbps (1,000 Mbps). This speed increase is achieved by altering the physical characteristics while leaving the rest of the levels equal.

Gigabit Ethernet considers three transmission media:

• Long wavelength (Long Wave) laser with single-mode or multimode fiber
• Short wavelength (Short Wave) laser with multimode fiber
• 150-ohm shielded twisted pair cable