Computer Networks Overview

Overview

This lecture introduces computer networks, their types, benefits, network topologies, and basic network architectures.

Introduction to Computer Networks

• A computer network connects two or more computers using communication channels (wired or wireless).
• Computer networks allow sharing of information and hardware resources among connected devices.
• Like railway networks, computer networks facilitate movement (of data) between nodes (computers).

Benefits of Computer Networks

• Enable sharing of data, applications, and hardware (e.g., printers) among multiple users.
• Reduce data redundancy by storing common files centrally for access by multiple users.
• Lower costs by sharing hardware (e.g., one modem provides internet to several devices).
• Improve security via tools like firewalls to protect data and prevent unauthorized access.

Types of Computer Networks

• Personal Area Network (PAN): Connects devices within ~10 meters, typically for personal use (e.g., laptop and smartphone).
• Local Area Network (LAN): Covers a small area like a room or building; provides fast data transfer; uses wired (LAN) or wireless (WLAN) methods.
• Metropolitan Area Network (MAN): Spans a city; connects multiple LANs using wired or wireless communication (e.g., bank ATMs).
• Wide Area Network (WAN): Connects computers over long distances (even continents) using technologies like satellite links.

Network Topologies

• Network topology: The arrangement of devices and connections in a network.
• Logical topology: Defines data flow between network components.
• Physical topology: Defines physical arrangement of devices.

Types of Topologies

• Point-to-Point: Direct connection between two devices.
• Bus Topology: All computers connect to a main cable (backbone); failure of the main cable breaks the network.
• Star Topology: Each device connects to a central server or hub; easy to add devices; network fails if hub fails.
• Ring Topology: Devices arranged in a circle; data circulates until it reaches its destination; one device failure can break the network.
• Tree Topology: Combines star and bus; hierarchical parent-child structure; difficult to manage and needs more cabling.
• Mesh Topology: Devices interconnect arbitrarily; high reliability but costly; common in wireless networks.

Network Architectures

• Peer-to-Peer (P2P): All connected devices have equal roles; no central server.
• Client-Server: Central server provides services to client computers, controls access, and manages resources.

Key Terms & Definitions

• Computer Network — A system of interconnected computers sharing resources and information.
• PAN (Personal Area Network) — A network for personal devices within a short range.
• LAN (Local Area Network) — A network within a limited area like a building.
• MAN (Metropolitan Area Network) — A network spanning a city.
• WAN (Wide Area Network) — A network covering large geographic areas.
• Topology — The physical or logical arrangement of network components.
• Peer-to-Peer Network — Network where each computer has equal status.
• Client-Server Network — Network with central server serving multiple clients.

Action Items / Next Steps

• Review the different types of computer networks and their topologies.
• Memorize key advantages of each network type and topology.
• Prepare for a quiz on network terminologies and architectures.