Learning: The switch learns the MAC address of the devices connected to each port by checking the source MAC address in the received data frame, and records it in its own MAC address table.

Forwarding: When a switch receives a data frame, it checks the destination MAC address and searches for the corresponding port in the MAC address table. If a matching entry is found, the data frame is forwarded from the corresponding port so that the data can accurately reach the target device.

Broadcast: If the switch cannot find the destination MAC address in the MAC address table, it will broadcast the data frame from all ports except the receiving port to find the target device. When the target device responds, the switch will learn its MAC address and update the MAC address table so that subsequent communication can be directly forwarded.

major function 

Port expansion: Multiple network devices can be connected together to expand the number of network connections. For example, in an office, there are multiple computers, printers, and other devices that can be connected to the same network through a switch, enabling communication and resource sharing between the devices.

Data exchange: It can quickly and efficiently exchange data between multiple ports, enabling simultaneous data transmission between different devices and improving network bandwidth utilization. For example, in an enterprise network, employees' computers can interact with servers and other employees' computers simultaneously without interfering with each other.

Network segmentation: A large network can be divided into multiple smaller network segments to reduce the scope of network conflict domains and improve network performance. For example, in a campus network, the network of different teaching buildings can be divided into different network segments through switches, reducing the possibility of network congestion.

VLAN partitioning: Supports virtual local area network (VLAN) technology, which can logically partition physically connected devices into different virtual networks, achieving isolation and communication control between different VLANs. For example, in a company network, different VLANs can be divided according to departmental or business needs to improve network security and management efficiency.

• How does a switch work
• The difference between switches and routers