Network Devices Explained - Hub, Switch, Router, Firewall, etc.

Cisco is a critical player in providing IT infrastructure solutions to thousands of organizations. As a part of the learning and development of its network hardware devices and other products, Cisco also offers certification programs starting with CCNA for beginners comes under Cisco enterprise training and certification.  

It covers the core networking concepts, and students learn and build a strong foundation for grasping advanced technologies. In this article, we will explain core network devices in computer networks, and look at their working and uses.

List Network Hardware Devices

This is the first topic of the Cisco CCNA course syllabus. Here is the list of important devices used in networking, there may be more peripherals and components.

1. Hub

2. Switch

3. Bridge

4. Router

5. Firewall

6. Intrusion Prevention System (IPS)

7. Wireless Access Point (WAP or AP)

8. Wireless LAN Controller (WLC)

9. Cisco Digital Network Architecture (DNA)

10. Advanced Programmable Interrupt Controller (APIC)

11. Cisco Nexus Switches

12. Cisco IP Phones

13. Cisco Storage Devices (UCS)

In this blog, we will be covering the main components of computer networks and their role & function, which are a part of CCNA, and will understand them based on real scenarios and device configurations.

This will help you to better understand the network hardware devices and how they work in the production environment. Additionally, if you want to learn concepts with hands-on practice via instructor led live CCNA training. Feel free to contact our learning advisor for any further details.

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Types of Network Devices

There are different types of network devices in an IT infrastructure each serving its role. Here is the list of some network devices that lay down the foundation of networking:

● Router: Connects multiple networks, directing data packets between them and managing traffic.

● Switch: Connects devices within a local network, forwarding data only to the intended recipient to improve efficiency.

● Hub: A basic device that connects multiple Ethernet devices, broadcasting data to all connected devices, which can lead to network congestion.

● Bridge: Connects and filters traffic between two or more network segments, reducing collision domains and improving performance.

● Access Point: Provides wireless connectivity to a wired network, allowing devices to connect without cables and expanding network coverage.

● Firewall: Monitors and controls incoming and outgoing network traffic based on predetermined security rules, protecting the network from unauthorized access.

● Modem: Modulates and demodulates signals for data transmission over telephone lines or cable systems, connecting a local network to the internet.

Network Hardware Devices - Role and Functions

Let us now understand these networking devices in detail.

Network Router

Routers are the core component of the networking devices that you see in the organization's data centers branch offices or small home office network.

The router in the computer network operates on the network layer which is Layer 3 of the OSI model.

The primary role of a router is to connect two or more different networks which facilitates the exchange of data packets between the networks.

The network router can make decisions based on the destination IP addresses present in the received packets. It determines the most appropriate outgoing interface based on the existing routing table for forwarding those packets to the next router in the network.

These routing tables are formed with the help of static routes or routing protocols like OSPF, EIGRP or BGP etc.

We will understand the functionality of the router based on the below scenario. Understanding IP addressing is essential before proceeding as these are the critical elements of network building blocks.

In a corporate network or a small home office network, typically router's interface connects to an internal network called the local area network (LAN) and the other interface connects to the internet or WAN or network gateway. 

When an internal device which is a part of the LAN in a computer network initiates a data packet, this router first receives these data packets and looks up the destination IP address present inside the data packets.

Based on the routing table (As depicted in the below diagram, here routing table is built from a configured default route) it then forwards them to the appropriate interface to send on the internet.  

The return data packets are received by the router and forwarded to the same devices that generate those data packets. 

Here is the Cisco network router configuration:

In this example, the router in the computer network has two interfaces. The router network interface GigabitEthernet0/0 is connected to the LAN with the IP address 192.168.1.1, and the network interface GigabitEthernet0/1 is connected to another network called Internet with the IP address 10.0.0.1. 

The "ip route" command sets the default gateway for the network router, specifying that any traffic with unknown destinations should be forwarded to the IP address 10.0.0.254. Sometimes this refers a gateway in a computer network or just a gateway network.

Switch in Computer Network

The switches that are operated at Layer 2 and Layer 3 of the OSI model have different functionalities. Here are some of the Cisco switch models. 

Layer 2 switches operate at the data link layer (Layer 2) and primarily focus on forwarding Ethernet frames based on MAC addresses.

They build and maintain MAC address tables to learn which devices are connected to which switch ports. Layer 2 switches are responsible for local network segmentation, improving network performance, and reducing collision domains.

Let's take a scenario to understand the functional role of another network hardware device i.e. switch

In an office network, a Layer 2 switch connects multiple computers and devices within a LAN.

When a device sends data to another device within the same LAN, the Layer 2 switch examines the MAC addresses in the Ethernet frames and forwards them to the correct destination port.

Devices in the same VLANs can communicate with each other while devices in different VLANs require their respective VLAN gateway IP addresses configured either on Layer 3 switch or a router. 

Here is the configuration of a Layer 2 switch.

In this example, the switch has two ports configured as access ports. Port FastEthernet0/1 is assigned to VLAN 10 (Sales), and port FastEthernet0/2 is assigned to VLAN 20 (Marketing). The "vlan" command is used to create the VLANs and assign names to them.

Layer 3 switches in computer networks, also known as multilayer switches, combine the features of Layer 2 switches with routing capabilities found in routers. They can perform routing functions at wire speed and facilitate inter-VLAN communication by routing traffic between different VLANs.

A this point you may be wondering if we already have routers that work at layer 3 then what these layer 3 switches do and what are the differences between router and switch.

Sometimes in a network, it is required to have multiple VLANs for various reasons. In that case, a Layer 3 switch can be configured as a default gateway for these VLANs. These VLANs can then route traffic between each other on the switch. It examines the IP addresses in packets and forwards them based on the routing table entries.

Here is the configuration of a Layer 2 switch.

In this example, the switch has a trunk port (GigabitEthernet0/1) to carry VLAN traffic. Two VLAN interfaces (Vlan10 and Vlan20) are configured with IP addresses. The "ip routing" command enables routing functionality on the Layer 3 switch. These IP addresses are the gateways on the devices in their respective VLANs,

The above-mentioned switches are Cisco catalyst switches and mostly you can use them as access switches in live production environments where users are directly connected. You can learn about these switches with some basic training and hands-on exercises.

There are several other types of network hardware devices used and offered by Cisco from their data center product portfolio. 

There are heavy-duty data center cisco nexus switches, you can use these switches where they can handle a high volume of network traffic and scalability is not a challenge. These nexus switches also come up with fully functional automation through software software-defined networks called cisco aci switches used in plug-and-play environments.

Once you are comfortable with cisco access switches you can go ahead and start learning Cisco Nexus and aci switches either through self-paced videos or via instructor-led live training. Learning these skills will keep you on top and will give you much more opportunities in the near future. 

Next-Generation firewalls

Next-generation firewalls (NGFWs) and Intrusion Prevention Systems (IPS) are the security of network hardware devices or software designed to protect vulnerable networks from malicious activities, unauthorized access, and threats.

Cisco Firepower is a cutting-edge security solution for protecting networks from advanced threads and attacks. It is a relatively new device so there is not much training available on the internet for free.

However, organizations are deploying at large scale. Live training on cisco firepower will equip professional candidates to manage, operate, and implement such security solutions. Even professionals who are already working on such devices, they required to test some features on proof of concept firepower virtual labs before deploying on production equipments.

Here just focus on basic network hardware types and initial configuration of these devices, but you can certainly go ahead and learn more about it either from Cisco or UniNets live training. 

The picture below is the Cisco Firepower 1000 series appliances, this is considered as NGFW.

NGFWs combine traditional firewall features (such as stateful packet inspection) with advanced capabilities such as application-layer filtering, user identity awareness, and threat intelligence.

They inspect network traffic at multiple layers, including application, transport, and network layers, to enforce security policies and prevent unauthorized access. Below are a couple of scenarios where IPS or NGFW is used.

Scenario 1: In an enterprise network, an NGFW is deployed at the network perimeter to inspect incoming and outgoing traffic. It can block malicious websites, detect and prevent intrusions, and provide granular control over network applications and user access.

IPS systems monitor network traffic for suspicious patterns or known attack signatures. They analyze packets in real-time to identify and block malicious activities.

Scenario 2: In a data center environment, an IPS is deployed to monitor traffic between servers. It can detect and prevent attacks like DDoS, SQL injection, and buffer overflow by inspecting the content of network packets.

Here's a simplified example of configuring access control policies on a Cisco NGFW (ASA):

In this example, an access control list (ACL) is created to permit web traffic (TCP ports 80 and 443). Another ACL denies all IP traffic.

A class map is defined to match the web traffic ACL, and a policy map is created to inspect HTTP and HTTPS traffic. The policy is then applied to the outside interface, and the access-group command applies the blocking ACL to the outside interface.

WiFi Network Devices - Access points

Access points (APs) are the wireless network hardware devices that are used to send Wi-Fi signals for providing wireless connectivity to the wireless devices in a specified area.  They act as a bridge between wireless devices and the wired network infrastructure.

The picture below is the Cisco Wireless Aironet 3600 series access points. 

In a Wi-Fi network, access points are strategically placed throughout an office building to ensure reliable wireless coverage. All the wireless components of computer networks supported devices such as laptop, phones, etc. try to connect to a wireless network, they first get themself attached to the nearest available access point.

The access point handles the transmission of data packets between wireless devices and the other network devices.

Here's a simplified example of configuring a Cisco Aironet access point:

In this example, the WiFi network access point has a wireless interface (Dot11Radio0) configured with the SSID "ExampleNetwork." The network interface GigabitEthernet0 is configured as a trunk port to carry multiple VLANs. The BVI1 interface is configured with an IP address for management purposes.

Controllers (Cisco DNA Center and WLC)

Controllers are network management devices that provide centralized management and control of various network components in computer networks, such as access points and switches.

Cisco DNA Center is a software-based network hardware type controller that enables centralized management, automation, and assurance for enterprise networks. It provides a single dashboard for managing types of network devices, implementing policies, and monitoring network health.

The picture below is the dashboard of DNAC.

The computer network hardware devices such as routers, switches, firewalls, access points, etc. are being managed and monitored by DNA Center.

It is preferably used in a large enterprise environment where it is difficult to manage them manually.

With the help of DNA, network engineers can perform various functions such as upgrading IOS on devices from a centralized location, and can also troubleshoot network issues without logging into each device.

As Cisco DNA Center is a software-based controller, there is no specific configuration example. However, typical tasks performed through the Cisco DNA Center include:

● Adding network devices (routers, switches, access points) to the inventory.

● Creating network profiles for devices and applying standardized configurations.

● Defining policies for network access, security, and quality of service.

● Monitoring network health, performance, and security.

● Automating network operations and deploying software updates.

The Cisco Wireless LAN Controller is a specialized controller designed for managing wireless networks. You can also learn further about it from a video course.

It centralizes the configuration, security, and management of access points. The picture below is the Cisco Wireless LAN Controller 5500 series. 

In a wireless network deployment, it's easy to configure and setup Cisco WLC which is used to manage multiple access points. It handles tasks such as AP discovery, client authentication, and radio resource management to ensure efficient and secure wireless connectivity. The WLC training videos explain the full process of discovery and authentication with hands-on exercises starting with the initial setup.

Network Hardware Types - Endpoints

Endpoints are also types of network hardware devices connected to the user ports of the switch in a computer network. These devices are the ones who send and receive the data for the end users such devices include laptops, desktops, cameras, phones, etc. 

In a typical office network, endpoints can include employee workstations, laptops, and mobile devices. Applications run on these devices to perform tasks like sending emails, sharing files, browsing the internet etc. 

Network Servers

Servers are high-end computer network hardware devices that provide resources such as CPU, RAM, Hard disk for storage, etc. for executing various services on a network. They are designed to handle specific tasks and deliver resources efficiently.

Basically there are 2 most popular i.e. open source Linux servers and proprietary Windows servers. In Linux, there are several flavors like Ubuntu, Redhat, kali, use, etc. with their release versions and similarly, in Windows we have Windows 2010, 2012, 2016, etc. 

Scenario: In an enterprise network hardware types like servers play a crucial role in providing various services. These services include storage, computing, web hosting, email service, database, etc. 

Power over Ethernet (PoE)

PoE is a technology that provides power and data to the end network components in computer networks over the same ethernet cable.

With PoE, power-sourcing equipment (such as PoE switches) can deliver electrical power to PoE-enabled devices without the need for separate power cables.

The picture below is the Cisco Catalyst c2960x 48 port PoE switch, a normal twisted pair ethernet cable is required to connect from switch ports to the end devices such as access point (access point does not require any other external power) to withdraw power.

In a network deployment, PoE is commonly used to power up the components of computer networks such as IP phones, wireless access points, and security cameras etc.

This eliminates the need for additional power outlets near these devices and simplifies cabling.

Here's an example configuration for a Cisco PoE switch:

In this example, GigabitEthernet0/1 is configured to automatically detect and provide power to a connected PoE device. GigabitEthernet0/2 is configured to deliver a static amount of power (15,000 milliwatts) to the connected device.

Network Devices- Summing Up!

Network devices are essential components that facilitate communication and data transfer within a network. Key devices include routers, which direct traffic; switches, which connect devices within a network; and access points, which enable wireless connectivity.

Proper configuration of these devices ensures efficient network performance, security, and reliability, making them crucial for both small and large-scale networks. Understanding their functions and configurations is vital for effective network management and optimization.