In the daily work of network engineers, switches are among the most frequently encountered devices.

Configuring VLANs, planning trunks, troubleshooting loops, adjusting link aggregation, optimizing link bandwidth...

These operations have become "muscle memory" for many network engineers.

But if we delve deeper into this question: what category do the switches you configure every day actually belong to?

Are they access switches or core switches?

Layer 2 switches or Layer 3 switches?

Campus switches or data center switches?

Many people might be able to give some answers, but few have a comprehensive understanding of the switch classification system.

In reality, switches are not a single device, but rather a category formed by multiple dimensions such as application scenarios, network layers, functional capabilities, performance specifications, and hardware architecture.

Understanding these classifications not only helps us to better understand network structures but also provides more valuable references when selecting equipment, planning networks, and troubleshooting.

Basic functions of a switch

At its most basic level, the main function of a switch is to forward data within a local area network (LAN) to enable communication between devices. Compared to routers, switches focus more on data forwarding within the LAN than on path selection across networks.

1. The basic working principle of a switch

Switches forward data based on MAC addresses, not IP addresses.

In actual operation, the switch maintains a MAC address table, which records the port corresponding to each MAC address.

When a switch receives a data frame, it goes through the following process:

Learn the source MAC address and record it in the MAC address table.

Query the port corresponding to the target MAC address.

If the target port is found, perform a redirected forwarding.

If the target MAC address is not found, perform flooding.

This mechanism determines the core position of switches in Layer 2 networks.

2. Switch expansion functions

As network scale expands, the functions of switches also become more diverse.

In addition to basic data forwarding functions, modern switches typically also support:

VLAN (Virtual Local Area Network)

Spanning Tree Protocol (STP / RSTP / MSTP)

Link Aggregation (LACP)

QoS (Quality of Service) control

ACL (Access Control List)

Network security related functions

These features have enabled switches to evolve from "simple forwarding devices" into "network devices with certain control capabilities".

Switch types categorized by application scenario

From the perspective of usage environment and application scenarios, switches can be divided into several typical types.

This classification method mainly reflects the differences in the "service objects" and "usage environments" of switches.

1. Campus Switch

Campus switches are mainly used in campus networks of enterprises, schools, government agencies, etc.

The characteristics of this type of network are:

• Large number of users
• Complex business types
• The network structure is hierarchical.
• High requirements for stability and manageability

Campus switches are typically distributed across the access layer, aggregation layer, and core layer, covering the entire network structure from the terminal to the core.

2. Data Center Switches

Data center switches are primarily used in IDC (Internet Data Center) rooms, cloud computing platforms, and large-scale server clusters.

Compared to campus networks, data center networks focus more on:

• Bandwidth capability
• Forwarding performance
• low latency
• Scalability

In data center scenarios, switches typically adopt a Spine-Leaf architecture and support new network technologies such as VXLAN and EVPN.

3. Industrial switches

Industrial switches are mainly used in special scenarios such as industrial control, transportation, and power.

The characteristics of this type of switch are:

• It can adapt to harsh environments (high temperature, low temperature, vibration, humidity).
• High reliability design
• Typically supports redundant power supplies and link protection mechanisms.

In industrial networks, stability is often more important than performance.

4. Virtual Switch

With the development of virtualization and cloud computing, switches are no longer limited to hardware devices.

A virtual switch is a type of switch that runs at the software level, for example:

• Open vSwitch（OVS）
• VMware vSwitch
• Virtual network components from major cloud vendors

Virtual switches are primarily used for network communication between virtual machines and are an important component of cloud computing networks.

Switch types classified by network layer

In enterprise networks, switches are typically deployed according to network layers.

This classification method is mainly used to describe the location and role of switches in the network.

1. Access layer switch

Access layer switches are located at the very edge of the network and are directly connected to terminal devices.

Common connection objects include:

• PC
• Wireless AP
• IP telephony
• Camera
• Internet of Things (IoT) devices

The characteristics of access layer switches are:

• Large number of ports
• Relatively low cost
• Relatively basic functions

2. Aggregation layer switch

Aggregation layer switches are located between the access layer and the core layer, and are mainly used to aggregate traffic from the access layer.

Its main features include:

• Higher forwarding performance
• Supports policy control (such as ACL, QoS)
• It typically has three layers of functionality.

3. Core layer switch

The core layer switch is located at the center of the network and is the backbone of the entire network.

Core layer switches typically have:

• Extremely high forwarding performance
• High reliability design
• Redundant power supplies, fans, and links

In large networks, core layer switches often adopt a chassis structure.

Switch types classified by functional level

From a protocol layer perspective, switches can be divided into Layer 2 switches and Layer 3 switches.

1. Layer 2 switch

Layer 2 switches operate at Layer 2 of the OSI model, namely the data link layer.

Its main functions include:

• MAC address learning and forwarding
• VLAN segmentation
• Spanning Tree Protocol
• Link Aggregation

The characteristics of a Layer 2 switch are:

• It does not have routing functionality.
• Mainly used for communication within a local area network

2. Layer 3 switch

Layer 3 switches operate at Layer 3 of the OSI model, namely the network layer.

In addition to Layer 2 functionality, Layer 3 switches also have:

• Inter-VLAN routing
• Static routing and dynamic routing protocols (such as OSPF and BGP)
• More complex access control policies

Layer 3 switches have become the mainstream equipment in enterprise networks.

In many cases, the routing function of an enterprise's internal network is mainly handled by Layer 3 switches, rather than traditional routers.

Switch types categorized by port speed

The performance of a switch is usually closely related to its port speed.

Based on port speed, switches can be categorized as follows:

1. 100Mbps switch

The port speed of a 100 Mbps switch is 100 Mbps.

Currently mainly used for:

• Old network
• For scenarios with low bandwidth requirements

2. Gigabit switch

The port speed of a gigabit switch is 1 Gbps.

This is the most common type of switch in enterprise networks today.

3. 10 Gigabit Switch

The port speed of the 10 Gigabit switch is 10 Gbps.

Mainly used for:

• Core layer network
• Data Center
• High-bandwidth service scenarios

4. Multi-rate switch

Multi-rate switches support multiple rates, such as: 100M / 1G / 2.5G / 5G / 10G

This type of switch is typically used in network environments that support WiFi 6/WiFi 7.

Switch types classified by hardware architecture

From a hardware structure perspective, switches can be divided into box switches and chassis switches.

1. Box switch

Box-type switches feature an integrated design and a fixed number of ports.

Its characteristics are:

• Small size
• Easy to deploy
• Low cost

Box-type switches are typically used for:

• Access layer network
• Small and medium-sized enterprise network

2. chassis switch

The chassis switch features a modular design, allowing for the plug-and-play of boards, power supplies, and fans.

Its characteristics are:

• Highly scalable
• High reliability
• Support large-scale networks

Chassis switches are typically used for:

• Core layer network
• Large data centers

Switch types categorized by management method

Different switches have significantly different management capabilities.

1. Unmanaged switch

Unmanaged switches typically do not support configuration functions.

Its characteristics are:

• Plug and play
• Simple function
• Low cost

Applicable to:

• Home network
• small office

2. Web-managed switch

Web-managed switches support management via a web browser.

Its characteristics are:

• The configuration interface is intuitive.
• Limited functionality

Applicable to:

• Small and medium-sized enterprise network

3. Fully managed switch

Fully managed switches support multiple management methods, such as:

• CLI（command line）
• SNMP
• Web Management
• API Interface

This type of switch is typically used for:

• Enterprise Network
• Data Center

In practical applications, a single switch often belongs to multiple categories simultaneously.

For example:

• A "Campus Core Layer 3 10 Gigabit Chassis Switch"
• A gigabit access layer box switch
• A "data center switch"

These descriptions are actually a combination of multiple classification dimensions.

Understanding this helps us to better understand the role of switches in a network.

To more intuitively understand the classification system of switches, a table can be used to summarize it.