Introduction to Computer Networks - Chapter 1

Computer Networks

• Computer networks connect multiple devices to share resources and communicate.
• Key components include Network Interface Card (NIC), Hub, Switch, Router, Modem, Repeaters, Firewalls, and Servers.

Introduction to Networks

• Chapter 1 covers fundamental network concepts.

Computer Network Components

• Network Interface Card (NIC): Hardware component connecting a computer to a network.
• Hub: Hardware device distributing network connections among multiple devices. It broadcasts requests to the entire network.
• Switch: Hardware device connecting multiple devices on a network. More advanced than a hub.
• Router: Hardware device connecting a Local Area Network (LAN) to an internet connection. Receives, analyzes, and forwards incoming packets to another network.
• Modem: Hardware device connecting a computer to the internet over existing telephone lines.
• Repeater: Networking device amplifying and regenerating incoming signals, thus extending network distances.

Network Interface Card (NIC)

• A NIC is hardware that connects a computer to a network.

Hub

• A hub is hardware that divides network connections among multiple devices.
• Hubs broadcast network requests to all connected devices.

Switch

• A switch is more sophisticated hardware that connects multiple network devices.
• Switches do not broadcast requests. They only transmit to the required device.

Router

• A router connects a LAN to an internet connection.
• It analyzes and forwards incoming network packets.

Modem

• Modems connect computers to the internet using existing telephone lines.

Repeater

• Repeaters boost signal strength, enabling network expansion.

Firewall

• A device, either hardware or software-based, that controls incoming and outgoing network traffic.
• Firewalls use security rules to accept, reject, or drop specific traffic.
• They act as barriers between a protected network and untrusted networks (like the internet).

Servers

• Computers with operating systems holding shared data on a network.
• Common servers include file servers, mail servers, print servers, web servers, fax servers, application servers, and telephony servers.
• Proxy servers handle tasks for other network devices, particularly for internet connections.

IEEE

• The Institute of Electrical and Electronics Engineers (IEEE) is the world's largest technical professional organization.
• It sets standards for computer networks, enabling smooth communication between various devices.

Ethernet

• Ethernet is a standard wired networking technology used in LANs and WANs.
• It establishes a common language for devices to format and send data.
• Ethernet cables transmit data. A standard wired network connecting devices together.

Communication Media

• Twisted pair cable, coaxial cable, fiber optic cable, and wireless are examples of network media.
• These transmit signals between network devices.

Twisted-pair cable

• Consists of multiple individually insulated wires twisted together in pairs.
• Common connector types include RJ-11 and RJ-45.

Straight-through cable

• Used for connecting devices at different network layers (e.g., connecting a computer to a switch).
• Often called patch cables.

Crossover cable

• Used to connect devices operating at the same network layer (e.g., connecting two computers directly).
• Wiring standards differ on each end of the cable.

Rolled/Console cable

• Used to connect a computer terminal to a router's console port.
• This cable is typically flat and light blue to distinguish it.

Fiber Optic cable

• Transmits digital signals using light impulses rather than electricity.
• Immune to EMI and RFI.
• Can carry signals farther than traditional electrical cables.

Wireless Technologies

• Technologies like Bluetooth and Wi-Fi enable wireless communication between devices.
• Bluetooth connects multiple devices in a short range. Wi-Fi uses access points to connect wireless devices to a wired LAN.

Half-duplex Ethernet

• Uses only one wire pair at any given time for transmitting or receiving digital signals.

Full-duplex Ethernet

• Uses two wire pairs simultaneously for transmitting and receiving signals.

Simplex, Half-duplex, and Full-duplex Comparisons

• Simplex transmits only in one direction.
• Half-duplex transmits in either direction but not both at once.
• Full-duplex transmits in both directions simultaneously.

Network Communication Types

• Unicast: Message sent from one sender to one receiver.
• Broadcast: Message sent from one sender to all recipients in the network.
• Multicast: Message sent from one sender to a specific group of recipients.