NETWORK DEVICES

Network Device

A physical device used to connect computers or other hardware in a network, enabling communication by forwarding, translating, or filtering data.

Purpose of Network Devices

To enable communication between networked devices and manage data transmission.

Hub

A simple device that broadcasts data to all connected devices without filtering or addressing.

Advantages of a Hub

Simple, cheap, and easy to install.

Disadvantages of a Hub

Causes network congestion and has no control over data direction.

Switch

A device that connects multiple computers within a LAN and forwards data only to the intended recipient using MAC addresses.

Advantages of a Switch

Reduces data collisions, increases efficiency, and improves network performance.

Disadvantages of a Switch

More expensive than hubs.

Router

A device that connects two or more networks and directs data packets between them.

Main Function of a Router

Routes data based on IP addresses to ensure data reaches the correct destination.

Types of Routers

Wired router, Wireless router, Core router, Edge router.

Wired Router

A router that connects directly to devices using Ethernet cables.

Wireless Router

A router that provides Wi-Fi connectivity to wireless devices.

Core Router

A high-capacity router used by ISPs to direct data within large networks.

Edge Router

A router that connects internal networks to external ones such as the Internet.

Modem

A device that modulates and demodulates analog and digital signals for Internet communication.

Function of a Modem

Converts data between analog (telephone or cable lines) and digital (computer) formats.

Difference Between Modem and Router

A modem connects to the ISP, while a router connects multiple devices to form a local network.

Network Interface Card (NIC)

A hardware component that connects a computer to a network and transmits/receives data packets.

Function of NIC

Converts analog-to-digital and digital-to-analog signals for communication.

Bridge

A device that connects and filters traffic between two LAN segments based on MAC addresses.

Purpose of a Bridge

Reduces network traffic and extends network segments.

Gateway

A device that connects different network environments and performs protocol translation between them.

Unique Feature of a Gateway

Operates across multiple OSI layers and handles data from dissimilar systems.

Firewall

A hardware or software-based security system that monitors and controls incoming and outgoing network traffic.

Main Function of a Firewall

Protects the network by preventing unauthorized access or attacks.

DTE (Data Terminal Equipment)

Devices that generate or receive digital data like computers and routers.

DCE (Data Circuit-Terminating Equipment)

Devices that transmit or receive data signals like modems and NICs.

Main Role of DTE

Produces and uses data in communication.

Main Role of DCE

Converts and transmits signals, providing timing and synchronization for communication.

Examples of DTE Devices

Computers, routers, servers, smartphones, printers.

Examples of DCE Devices

Modems, NICs, ISDN adapters, satellites, radio transmitters.

OSI Model

A reference model that defines how data is transmitted and received across networks in seven layers.

Data Flow in the OSI Model

Data moves down the sender’s layers (Application → Physical) and up the receiver’s layers (Physical → Application).

Data Encapsulation

Each OSI layer adds its own header or trailer to the data before transmission.

Data De-encapsulation

The receiver removes headers and trailers layer by layer until the data is readable by the application.

Importance of the OSI Model

Standardizes network communication and ensures interoperability between different systems and devices.

Difference Between DTE and DCE

DTE creates or receives data, while DCE manages signal conversion and timing to transmit it.