Network Devices Explained: A Simple Guide

Introduction

Think of your home or office network as a city. Your computers, printers, and phones are the buildings, but what connects them? The roads, intersections, and traffic signals, these are the network devices.  

Simply put, network devices in computer networks are the physical components that connect electronics, allowing them to communicate and share resources.  From the router that brings the internet into your home to the switch that directs traffic between your devices, these components form the backbone of any functional network. 

This tutorial will introduce you to the most common network devices, explaining their specific functions, types, and how they work together to keep us all connected. 

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Repeater

A repeater strengthens and retransmits signals over the same network to avoid corrupt messages from being received.

Hub

A hub is essentially a multiport repeater on a given LAN that broadcasts messages to all connected devices without filtering data.

Bridge

A bridge is like a repeater that can filter data and connect two separate LANs.

Switch

Switches are multiport bridges with the ability to perform error checks and forward data to the intended port only.

Router

A router network device directs data packets between networks using their IP addresses, ultimately connecting LANs and WANs.

Other network devices include gateways, NICs, routers, etc.

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Hubs and Types of Hubs

A hub is a device that makes room for multiple connections in a computer network between both computers and other hardware devices. It links all the stations and operates on the physical layer of the OSI model. For example, an aux hub allows multiple mics to connect to the speakers in a sound system.

However, hubs cannot filter the received information, only relay it. Packets are forwarded to all devices connected to the network. All connected hosts share the collision domain. This may lead to inefficiency.

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Hubs are furthermore classified as below.

1. Active Hub: Like repeaters, active hubs regenerate and amplify received messages before broadcasting them to hosts. They have an internal power supply and are both connecting center and repeater. This allows them to expand the distance between nodes and increase LAN size.
2. Passive Hub: Connect nodes by collecting wiring from nodes and power supply from active hubs. Broadcasted messages are neither regenerated nor amplified, meaning that they cannot contribute to optimizing nodal distance and hence limit LAN size. They are just connectors.
3. Intelligent Hub: Active hubs that allow network management via traffic monitoring, providing flexible data rates, port configuration, etc.

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Bridge and Types of Bridges

The bridge is a device that connects two separate LANs using different protocols or two segments of a LAN. It accepts all data packets and amplifies them before selectively relaying information to the intended host using the MAC addresses of the source and destination. Therefore it acts like an intelligent repeater that connects smaller networks to form extended LANs. It has singular input and output and is a two-port device.

It is important to note that bridges do not filter data; they relay information selectively based on addresses, reducing collision and traffic.

Bridges are generally classified into two types, as given below:

1. Transparent Bridges: The end systems on the network are oblivious to the existence of these bridges and their configuration; they act like 'plug-and-play' bridges. These are self-updating and maintain a table of terminal addresses. Disconnecting transparent bridges does not require reconfiguration.
2. Source Routing Bridges: Used in Token Ring networks, the source system performs the routing action while the frame specifies which route to follow. So effectively, not only does the frame contain source and destination addresses, but also the bridge address. The host can send a special discovery frame using all possible paths to the destination to discover the frame.

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Switch and Types of Switches

Like the Bridge, the Switch also operates on the data link layer. As mentioned earlier, a switch is a multiport bridge that can error-proof packets before forwarding them. Along with being efficient due to reduced traffic as a multiport device, it is also more precise as it only forwards 'good' packets to the 'right' host destination. This segments the collision domain while the broadcast domain remains the same.

Switches can be classified and sub-classified as follows:

1. Unmanaged Switches: Plug-and-play switches that do not require configuration or to be watched. These are most commonly used in home networks or small-scale networks as they use small cable connections in limited spaces. For example, they connect a PC to a Printer in a home office. They may be used for expansion to a larger network. Unmanaged switches are the most cost-effective option.
2. Managed Switches: Designed to deliver the most comprehensive set of features such as the best application experience, highest levels of security, management of the network, and scalability. Centralized management makes this an ideal and necessary cost for large networks. Scalability makes it suitable for expanding networks.
3. 1. Smart Switch: Also known as partially managed switches, these switches are easily set up and managed. Typically suited for small- to medium-sized networks, it can accept VLAN(Virtual LAN) configuration. They offer limited levels of security.
   2. Enterprise Managed Switches: Going by the tag of fully managed switches, these can fix, copy, transform, and display different network configurations, along with a web interface SNMP agent and command-line interface. Best suited for organizations with a large volume of ports, nodes, and switches, these are significantly more expensive than smart switches.

3. LAN Switches: They connect points on a LAN and reduce network traffic by broadcasting a data packet to its recipient alone. They can also be called Ethernet Switches/Data Switches.
4. PoE (Power over Ethernet) Switches: Designed to disentangle the cabling process, PoE Switches allow data and power to be integrated on the same cable. Therefore devices can receive both power and data simultaneously.
5. Layer 2 Switches: These switches operate at the 2nd Layer- Data Link Layer of the OSI (Open Systems Interconnection) model. They relay data between devices on the same segment of a network.
6. Layer 3 Switches: These switches operate at the 3rd layer- The network Layer of the OSI model. With the ability to route data among separate segments in a network, Layer 3 switches are used in complex expanded networks.
7. Rack-Mounted Switch: designed to attach to data racks, rack switches are ideal for use at large networks and data centers.
8. Desktop Switches: Smaller than rack-mounted switches, desktop switches are to be used on desktops or small-network/ work environments.
9. Modular Switches: Easily manageable and customizable, these switches come with a modular design. They are useful in large data centers and networks.

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That brings us to the end of Switches, but before we attempt to conclude, it might be useful to outline a few more devices.

Gateway is like a path or passage, as suggested by the literal meaning of the word, that allows separate networks to connect. Since these networks operate on separate networking models or protocols, a gateway converts data packets received from a system according to, before interpreting and transferring it to the other system. This is why they are also known as protocol converters.

Brouter stands for bridging router- meaning that it can work at Layer 2 (data link) or Layer 3 (network) by combining a router's and a bridge's functions. It can route packets as well as filter network traffic across a LAN.

And finally, the NIC, which is an interface card for the network, is a Layer 2 device that connects the host and the network itself. The card has a pre-inscribed distinct ID and a connector allowing the computer to connect to the router. The purpose of a NIC is to make room for setting up a LAN.

Conclusion 

In conclusion, the various network devices we've covered, from routers and switches to modems and firewalls—are the essential physical building blocks of any functional network.  

While each component has a unique role, they all work together as a team to direct traffic, translate signals, and keep our data flowing securely. A solid grasp of these network devices in computer networks is the first and most crucial step toward understanding how we all stay connected in a digital world. 

FAQs

1. What are network devices and what is their primary role? 

Network devices are the physical, electronic components that form the backbone of any computer network.  Their primary role is to connect various hardware endpoints (like computers, printers, and servers) and manage the flow of data between them. Think of network devices in computer networks as the traffic control system—the roads, signs, and signals—that allows data to travel from a source to a destination efficiently and securely. 

2. Do printers and computers count as Network Devices? 

No, while printers, fax machines, and computers are essential hardware devices on a network, they are not to be confused with network devices themselves. These endpoints are called hosts or clients. The actual network devices in computer networks are the 'middlemen'—like switches, routers, and hubs—that connect these host devices to each other and facilitate communication. For example, a hub is a network device that connects a host computer to a printer. 

3. What is the OSI model and why is it important for understanding network devices in computer networks? 

The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven abstract layers. It's incredibly important because it helps us understand the specific roles and responsibilities of different network devices. By knowing which layer a device operates on, we can understand exactly what kind of data it processes and how it contributes to the overall function of network devices in computer networks. 

4. What are Layers in the OSI model? 

The Open Systems Interconnection (OSI) model defines 7 layers over which computer systems and network devices communicate over a network. Each layer has a specific function, and understanding them is key to understanding network devices in computer networks. The 7 layers are: 

• Layer 1: Physical Layer (e.g., cables, hubs) 

• Layer 2: Data Link Layer (e.g., switches, bridges) 

• Layer 3: Network Layer (e.g., routers) 

• Layer 4: Transport Layer (manages data transfer, e.g., TCP/UDP) 

• Layer 5: Session Layer (manages sessions between applications) 

• Layer 6: Presentation Layer (data translation and encryption) 

• Layer 7: Application Layer (human-computer interaction, e.g., web browsers) 

5. What is the fundamental difference between a hub, a switch, and a router? 

This is a classic question when learning about network devices. 

• Hub (Layer 1): A hub is the simplest and least intelligent device. It receives data on one port and broadcasts it to every other port. This creates a lot of unnecessary traffic. 

• Switch (Layer 2): A switch is smarter. It learns the MAC addresses of the devices connected to it and sends data only to the intended recipient. 

• Router (Layer 3): A router is the most intelligent of the three. It connects different networks together (like your home network to the internet) and uses IP addresses to direct traffic between them. 

All three are fundamental types of network devices in computer networks. 

6. How does a modem fit in with other network devices like routers? 

A modem (Modulator-Demodulator) and a router are both crucial network devices, but they perform different jobs. A modem's job is to translate the signals from your Internet Service Provider (ISP) into a digital signal your computer can understand. A router's job is to create a local network and share that single internet connection among multiple devices. Many modern consumer-grade network devices in computer networks are combination modem-router units. 

7. At which OSI layer do common network devices like hubs, switches, and routers operate? 

Understanding the operating layer is key to understanding these network devices. 

• Hubs operate at Layer 1 (Physical Layer). They only deal with electrical signals (bits) and don't understand data structures. 

• Switches operate at Layer 2 (Data Link Layer). They work with data frames and use MAC addresses to make intelligent forwarding decisions. 

• Routers operate at Layer 3 (Network Layer). They work with data packets and use IP addresses to route traffic between different networks. 

These are the most fundamental network devices in computer networks and their respective layers. 

8. What is a bridge and what is its main function in computer networks? 

A bridge is one of the simpler network devices used to connect two or more separate network segments, making them appear as a single network. Its main function is to filter traffic between these segments. By reading the MAC address of each data frame, a bridge learns which devices are on which segment and will only forward traffic across the bridge if the destination device is on the other side. Using a bridge is a basic way to manage traffic among network devices in computer networks. 

9. At which layer does the Bridge operate? 

A Bridge is one of the key network devices that operates with MAC (media access control) addresses at Layer 2, the Data Link Layer, of the OSI model. By working at this layer, it can make intelligent decisions about whether to forward a data frame to another network segment, unlike a Layer 1 hub which just broadcasts everything. This makes it a crucial component among the foundational network devices in computer networks. 

10. What is a repeater and how does it help a network? 

A repeater is a Layer 1 network device used to regenerate and re-transmit a signal. In any network, a signal can weaken over long distances (a phenomenon called attenuation). A repeater takes a weakened signal, cleans it up, and broadcasts it again at its original strength, effectively extending the distance the network can cover. Repeaters are simple but essential network devices for large physical areas, ensuring that all network devices in computer networks can communicate effectively. 

11. Can a repeater filter data packets to prevent corruption? 

No, a repeater is one of the simpler network devices that only amplifies the electrical signal it receives without cleaning or filtering the data itself. Therefore, it cannot help in selective data broadcast or prevent corruption within the data packet. Its purpose is to combat signal degradation (loss of amplitude) over distance. To intelligently filter data, you need more advanced network devices in computer networks like a switch or a router. 

12. What is a gateway and how is it different from a router? 

A gateway is a network device that acts as an entry/exit point for a network, connecting two networks that use different communication protocols. While all routers are gateways (connecting a LAN to the internet's WAN), not all gateways are routers. A gateway can also translate between different protocols, like connecting a voice over IP (VoIP) network to the traditional telephone network. It's a versatile type of network device among the many network devices in computer networks. 

13. What is a Wireless Access Point (WAP) and how does it work? 

A Wireless Access Point (WAP) is a network device that allows wireless-capable devices (like laptops and smartphones) to connect to a wired network. It acts as a central transmitter and receiver of wireless radio signals. A WAP essentially converts the wired Ethernet signal from a router into a wireless Wi-Fi signal. It's one of the most common network devices today, essential for providing Wi-Fi coverage in homes and offices and connecting wireless clients to the broader world of network devices in computer networks. 

14. What is a Network Interface Card (NIC) and is it essential? 

A Network Interface Card (NIC) is a hardware component, typically a circuit board, installed in a computer so that it can be connected to a network. It provides the physical connection (like an Ethernet port or a Wi-Fi antenna) and the low-level addressing system (the MAC address). A NIC is absolutely essential; without it, a computer cannot physically or logically connect to other network devices. It's the fundamental component that makes a computer one of the addressable network devices in computer networks. 

15. Is a firewall considered one of the core network devices in computer networks? 

Yes, a firewall is absolutely considered one of the most critical security-focused network devices. Its job is to monitor incoming and outgoing network traffic and decide whether to allow or block specific traffic based on a defined set of security rules. A firewall can be a hardware device, a software program, or a combination of both. It acts as a barrier between a trusted internal network and an untrusted external network (like the internet), making it an essential security layer for all network devices in computer networks. 

16. What is the difference between managed and unmanaged network devices? 

The difference between managed and unmanaged network devices, particularly switches, comes down to control and features. 

• Unmanaged Devices: These are simple, plug-and-play devices with no configuration options. They are common in home networks. 

• Managed Devices: These offer advanced features and allow a network administrator to configure, monitor, and manage the network. This includes setting up VLANs, prioritizing traffic (QoS), and enhancing security. 

Choosing between them depends on the complexity of your requirements for network devices in computer networks. 

17. How do I choose the right network devices for a home setup? 

Choosing the right network devices for your home depends on your needs:  

• Router: Get a modern Wi-Fi router (Wi-Fi 6 or newer) that can handle the internet speed you're paying for and has enough LAN ports for your wired devices. 

• Modem: You'll need one that's compatible with your ISP. Often, this is a combination modem-router. 

• Switch: If you run out of ports on your router, a simple unmanaged Gigabit switch is an inexpensive way to add more wired connections. 

For most homes, these are the only network devices in computer networks you'll need. 

18. How have network devices evolved over the years? 

Network devices have evolved dramatically, moving from simple, "dumb" hardware to highly intelligent, software-defined systems. Early hubs gave way to more efficient switches. Routers have become incredibly powerful, with advanced security and traffic management features. The biggest evolution in network devices in computer networks is the rise of Software-Defined Networking (SDN), where the control logic is separated from the physical hardware, allowing for more flexible and centralized management of the entire network. 

19. Can a single piece of hardware act as multiple network devices? 

Yes, absolutely. Most consumer-grade "routers" you buy for your home are actually combination devices that perform the functions of multiple network devices. A typical home Wi-Fi router is a router (connects your LAN to the internet), a switch (provides multiple Ethernet ports), and a Wireless Access Point (creates the Wi-Fi network). This convergence makes setting up home network devices in computer networks much simpler and more cost-effective. 

20. Why is a deep understanding of network devices important for an IT career? 

A deep understanding of network devices is a non-negotiable, foundational skill for virtually any career in IT, from system administration to cybersecurity. Knowing how these components work allows you to design, build, and troubleshoot networks effectively. This knowledge of network devices in computer networks is critical for ensuring data flows efficiently and securely, which is the backbone of all modern business operations. At upGrad, our IT and software engineering programs emphasize these core networking principles to build a strong foundation for a successful tech career.