What is a Network Switch? Classification, Functions, and How It Works

What is a Network Switch?

A network switch is an intelligent networking device that primarily operates at the Data Link Layer (Layer 2) of the OSI model. It connects devices within a Local Area Network (LAN) and selectively forwards data between them based on the destination device’s MAC (Media Access Control) address.

Structure of a Network Switch

1. Hardware Components:

• Device Casing: The outer shell that protects the internal electronic components from environmental factors. It is usually made of plastic or metal.
• Power Supply: Provides the necessary power for the switch to function. It can be built-in or external.
• Ports: The connection points for various network devices via network cables. The number and type of ports (Ethernet, Gigabit Ethernet, SFP, etc.) vary depending on the switch model.

2. Electronic Circuit Components:

• CPU: The central processing unit acts as the “brain” of the switch, managing MAC address tables, VLANs, and other network functionalities.
• Memory: Stores essential data such as MAC address tables, switch configurations, and temporary data. It includes RAM (Random Access Memory) and ROM (Read-Only Memory).
• Motherboard: The main circuit board that connects all electronic components within the switch.
• System Bus: The internal data transmission pathway that allows communication between electronic components.
• Switching Chip: The most crucial component responsible for processing and forwarding data packets between ports.

Features of a Network Switch

Packet Forwarding

• This is the core function of a switch.
• When a data packet arrives at a switch port, the switch examines the destination MAC address.
• Based on its MAC address table, the switch determines the appropriate port for the destination device and forwards the packet accordingly.
• This process reduces unnecessary network traffic and improves performance.

Port-Based Connectivity

• Each port functions as a dedicated connection point for a single network device.
• This allows simultaneous connections between multiple devices without data collisions.
• Each port creates a separate collision domain, minimizing data interference.

Traffic Segmentation

• Switches can divide the network into smaller segments called collision domains.
• This reduces data collisions and improves overall network performance.
• VLAN (Virtual LAN) support enhances security and network management flexibility.

Broadcast Control

• Broadcast packets are sent to all devices in the network.
• Switches regulate the scope of broadcast packets, preventing excessive propagation and network congestion.
• This improves network efficiency and reduces bottlenecks.

Layer 2 Features:

• Operates primarily at the Data Link Layer (Layer 2) of the OSI model.
• Layer 2 functionalities include:

– Packet forwarding based on MAC addresses.

– VLAN support.

– Spanning Tree Protocol (STP) to prevent network loops.

Layer 3 Features:

• Some switches (Layer 3 switches) have routing capabilities, operating at the Network Layer (Layer 3).
• Layer 3 functionalities include:

– Inter-subnet routing.

– Packet processing and forwarding based on IP addresses.

Quality of Service (QoS):

• QoS prioritizes critical data traffic, ensuring smooth performance for latency-sensitive applications like VoIP (Voice over IP) and video streaming.
• Switches classify and prioritize traffic based on parameters such as IP address, port, or protocol type.

How Does a Switch Work?

Receiving Data Packets

• When a device within the network (e.g., a computer) sends data to another device, the data is divided into packets.
• These data packets are transmitted to the switch via network cables and connection ports.

Identifying MAC Addresses

• The switch examines the destination MAC address within the data packet.
• A MAC address is a unique identifier assigned to each network device.
• The switch utilizes a MAC address table to store information about the MAC addresses of devices connected to each of its ports.

Forwarding Data Packets

• Based on the destination MAC address, the switch searches the MAC address table to determine the port associated with the target device.
• The switch forwards the data packet only to that specific port, rather than broadcasting it to all ports like a hub.
• This reduces unnecessary network traffic and improves performance.

Collision Management

• Each port on a switch creates a separate collision domain.
• This helps minimize data collisions when multiple devices send data simultaneously.
• The switch employs techniques like CSMA/CD (Carrier Sense Multiple Access with Collision Detection) to detect and manage collisions.

Full-Duplex Communication

• Switches support full-duplex communication, allowing devices to send and receive data simultaneously.
• This enhances data transmission speeds and network performance.

Collision Detection

• In case of a collision, the switch detects it and sends a notification signal to the affected devices.
• These devices will pause transmission and attempt to resend the data after a random delay.

What is the difference between hub and switch and router and bridge?

Switch vs. Router

A network switch and a router are both essential networking devices, but they serve different purposes. A switch operates at the data link layer (Layer 2) of the OSI model, connecting devices within the same local area network (LAN) and facilitating efficient data transmission between them.

On the other hand, a router operates at the network layer (Layer 3) and is responsible for routing data between different networks. It enables devices to access the internet and communicate with external networks. Simply put, a switch is used for managing data within a LAN, while a router connects different networks and directs data traffic between them.

Switch vs. Hub

Both switches and hubs are used to connect multiple devices within a LAN, but they function differently. Hubs operate at the physical layer (Layer 1) of the OSI model, broadcasting data indiscriminately to all connected devices, which can lead to network congestion and reduced performance.

Switches, on the other hand, operate at the data link layer (Layer 2), identifying the MAC addresses of connected devices and forwarding data only to the intended recipient. This optimizes bandwidth usage and minimizes network collisions.

Switch vs. Bridge

Both Switches and Bridges operate at the Data Link Layer (Layer 2) of the OSI model, facilitating network connectivity and managing data flow. However, there are key differences between them:

Bridge is a simple device, typically with 2 to 4 ports, used to connect two network segments and filter data based on MAC addresses. It helps divide networks to reduce congestion but has slower processing speeds since it uses software for data analysis.

Switch is a more advanced device with multiple ports and faster data processing capabilities, thanks to hardware-based processing (ASIC). Switches can directly send data to the destination device without causing congestion, optimizing network performance.

In summary, Bridges are suitable for small networks, while Switches are a more efficient solution for large networks with high data transmission demands.

Comparison Table: Differences Between Switches, Routers, Hubs, and Bridges

Feature	Switch	Router	Hub	Bridge
Operating Layer (OSI)	Layer 2 (Data Link) and some Layer 3 (Network)	Layer 3 (Network)	Layer 1 (Physical)	Layer 2 (Data Link)
Main Function	Connects devices in a LAN, selectively forwards data	Connects different networks, routes data between them	Broadcasts data to all ports	Connects two LAN segments
Operation Method	Uses a MAC address table to determine the destination device	Uses routing tables and IP addresses to determine the path	Broadcasts data to all ports without filtering	Uses a MAC address table to filter and forward data between network segments
Performance	High	High	Low	Medium
Collision Domain	Each port creates a separate collision domain	No collision domain	All ports share the same collision domain	Two ports belong to different collision domains
Broadcast Domain	One broadcast domain (unless VLAN is used)	Creates separate broadcast domains for each connected network	One broadcast domain	One broadcast domain
MAC Address Learning	Yes	Yes (for LAN interfaces)	No	Yes
Routing Capability	Some Layer 3 Switches can perform routing	Yes	No	No
Applications	LAN networks, data centers	Connecting LANs to WANs, interconnecting LANs	Small, simple LANs (now rarely used)	Connecting two small LAN segments

Types of Network Switches

Unmanaged Switches are the simplest type, commonly used in home or small office networks. They operate on a “plug-and-play” principle, requiring no complex configuration. The biggest advantage of unmanaged switches is their affordability and ease of use.

Belden is a globally renowned cable brand that provides unmanaged switches with simple connectivity and easy plug-and-play functionality.

Managed Switches offer advanced features, allowing users to customize and manage networks flexibly. They are commonly used in large enterprises requiring high performance and security. Managed switches support features like VLAN, QoS, and STP to optimize network performance.

Layer 2 Switches operate at the data link layer in the OSI model. They forward data based on MAC addresses, reducing conflicts and improving network performance. These switches are suitable for standard LAN networks.

Layer 3 Switches have routing capabilities, functioning at the network layer in the OSI model. They can forward data between subnets, similar to routers. Layer 3 switches are often used in complex networks requiring flexible routing.

PoE Switches provide power over Ethernet cables, simplifying the installation of devices such as IP cameras and VoIP phones. They help save costs and installation space while increasing network flexibility. PoE switches are increasingly popular in surveillance systems and wireless networks.

Stackable Switches allow multiple switches to be combined into a single logical device, enhancing performance and manageability. They are commonly used in large enterprise networks that require high scalability. This switch type simplifies network management and reduces downtime.

Data Center Switches are specially designed for data centers, where high performance and reliability are essential. They support advanced technologies such as 10GbE, 40GbE, and 100GbE, ensuring rapid data transmission. These switches handle large traffic loads and maintain service continuity.

Smart Switches are a middle ground between managed and unmanaged switches. They provide basic management features, making them suitable for small to medium-sized businesses. This switch type balances cost and performance.

Modular Switches allow for expansion modules to be added, enabling customized configurations based on network needs. They are commonly used in large enterprise networks requiring scalability and flexibility. This switch type protects investment and ensures adaptability.

Benefits of Network Switches

Improved Network Performance: Network switches reduce data collisions, increase transmission speed, and optimize bandwidth. This is particularly crucial for high-traffic networks, where performance is key to ensuring smooth operation of applications and services.

Easy Network Management: Managed switches provide a centralized management interface, allowing administrators to easily configure, monitor, and troubleshoot from a single point. VLAN features help segment networks logically, simplifying device management and enhancing security.

Reduced Network Management Costs: Automation of various management tasks saves time and resources for administrators. QoS features prioritize critical traffic, optimize bandwidth usage, and reduce the need for hardware upgrades.

Enhanced Network Security: Switches support security features like VLANs, access control, and MAC address filtering, protecting networks from attacks and unauthorized access. This is particularly important in high-security environments such as businesses and financial institutions.

Better Scalability and Flexibility: Switches allow networks to be easily expanded by adding connected devices as demand grows. Stacking features enable multiple switches to function as a single logical unit, improving performance, manageability, and simplifying network operations.

Applications of Network Switches:

Network switches are widely used across various fields, including:

Data Centers

• Connects servers, storage devices, and other networking equipment.
• Ensures high performance and reliability for critical applications.

Home Networks

• Connects devices such as computers, TVs, and smart devices.
• Enables internet sharing and network resource access.

IP Surveillance Systems

• Connects IP cameras, video recorders, and other monitoring devices.
• Provides power through PoE (Power over Ethernet).

Wireless Network Expansion

• Connects Wi-Fi access points to extend coverage.
• Ensures stable and high-speed connections.

Belden Network Switches

Belden provides advanced network switch solutions, meeting connectivity needs in various environments, from complex industrial systems to simple applications.

Managed Switches

Belden offers a broad range of durable Managed Ethernet Switches, designed for stable operation in harsh industrial environments. With options supporting Layer 2 (Data Link Layer) and Layer 3 (Network Layer) or integrated SPE technology, you can find the right solution within the Hirschmann, GarrettCom, and Lumberg Automation product lines.

Unmanaged Switches

Additionally, Belden’s Unmanaged Switches offer a simple, user-friendly networking solution with plug-and-play functionality, enabling quick device communication without complex configurations. Whether you require a robust network system or a streamlined connectivity solution, Belden provides products to optimize performance and reliability for your network.

Servo Dynamics – Authorized Distributor of Belden in Vietnam

Servo Dynamics is the official authorized distributor of Belden in Vietnam, offering customers world-class industrial networking and communication solutions. With a strong reputation and extensive experience, Servo Dynamics is committed to providing high-quality Belden products along with professional support services, catering to the needs of Vietnamese enterprises in the industrial sector.