# Understanding Network Devices

In today’s world about 70% of human population use the Internet daily . But have you ever thought how we connect our Phones or PC or laptop or any devices to this World Wide Web . You connect to a ISP and they provide you a Network device which you use to surf web , pay bills , play Videogame or Learn something on the Internet . But what are these Network devices -

Network devices are machines which computers use to communicate and interact between themselves on a network . Depending on their functionality, these devices performs routing, protocol conversion, signal regeneration , packet switching etc. to ensure reliable, efficient, and secure communication.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769235025782/b80cd30e-1b0b-4959-83cd-a65c76b4e11f.png align="center")

Now lets talk about these Network Devices-

## Physical Layer Devices :

These devices works with electrical signal or optical signal , they don’t understand IP addresses or MAC addresses .

### Hub :

It acts as a connection point for multiple devices like-pc, phone , printer etc. and act as a junction point where data from one devices is broadcasted to others.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769236525627/87d06a71-f651-46c8-a82a-650a08685a11.png align="center")

### Repeater :

It is a hardware device that receives weak signal cleans it up , restores it’s original strength and retransmit it . It extends WIFI range and Ethernet cable over 100m .

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769236825318/0bea5cf8-e62f-4cd0-ac5a-40ff9f044ca2.png align="center")

### Modem :

A Modem or a Modular-DE modular is a important device which converts digital signal from our devices like- pc to analog signal for the transmission in the physical lines and vise-versa . It connects our PC to the ISP.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769237114093/d748ce0f-fd8a-4e77-a4c9-da95665e2627.png align="center")

## Data Link Layer Devices :

These Devices work with Physical Addresses.

### Switch :

Unlike a Hub, a Switch learns the MAC address of every connected device. It sends data **only** to the specific port where the destination device is connected.

### Bridge :

 Filters traffic based on MAC addresses to keep local traffic local, reducing congestion. Largely replaced by Switches (which are essentially multi-port bridges).

### Access Point :

Creates a wireless LAN , It acts as a bridge between wired Ethernet and wireless WiFi devices.

## **Network Layer Devices :**

These devices work with IP Addresses (Logical Addresses). They connect different networks together.

### Router :

Connects multiple networks (e.g., Home LAN to the Internet WAN). it uses IP Addresses to determine the best path for data packets to travel. It maintains a Routing Table to make these decisions.

## **Advanced Processing Devices :**

### **Gateway :**

A translator between two dissimilar networks. It can convert protocols, data formats, or architectures (e.g., connecting a TCP/IP network to a legacy Mainframe network).

### Firewall :

This is a Security Guard who Controls incoming and outgoing traffic based on security rules.

firewall Can be of two types - Hardware and Software .

It act as a barrier between a trusted network and an untrusted network like the Internet. It protects systems from unauthorized access, malicious threats, and can perform content filtering. 

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769260261350/9dc480fb-dba2-48ec-a502-4df29344f0da.png align="center")

## Confusion between devices :

### Switch vs Hub :

A **hub is like a loudspeaker** in a classroom. Whatever data comes in, it **sends to ALL computers** connected to it. Even if the message is for only 1 PC, **everyone gets it**.

but A **switch is like a teacher giving a note to only one student**. It sends data **only to the correct computer**, not all. It remembers devices using **MAC address**.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769260105528/405c60f5-9ea7-44f4-aec0-65d622d382ae.png align="center")

### Router vs Modem :

Modem Brings **internet from your ISP company to your home & Router** takes internet from modem and **shares it to multiple devices** like: PC , laptop , phones etc.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1769260153185/788d9573-9ebf-4a2f-89a5-d0cc0248023a.png align="center")