The Concept of VLAN (Virtual LAN)

 We all know that on the same LAN, the hub connection will create a conflict domain. While under the switch, the conflict domain can be resolved, there will be a broadcast domain. In order to solve this broadcast domain, it is necessary to introduce routers to divide different LANs into different broadcast domains in order to reduce broadcast domain interference between devices. Can we propose that the switch also have the function of this router? After development, the concept of VLAN is proposed. What is VLAN? 
“VLAN” means “Virtual Local Area Network.” 
A virtual local area network (VLAN) is logically divided into multiple broadcast domains, and each broadcast domain is a VLAN. How to divide it.
The following figure shows the switch is divided into virtual LANs. On the left, through internal settings, this switch divides a broadcast domain into three broadcast domains, VLAN1, VLAN2, and VLAN3. Physically, these devices are on one switch, but logically, they have been divided into three switches, so there will be three LANs (virtual LANs) and three broadcast domains. 

Partitioning switches into virtual LANs 
The VLAN division of the switch indicates that VLAN 1, the VLAN number, generally works in the management group, so the common VLANs are numbered from 2 to 3. By default, all VLANs belong to VALN1. 
The above is the explanation of the concept of VLAN, or virtual LAN, brought by Shenzhen Haidiwei Optoelectronics Technology Co., Ltd. The Shenzhen HDV Phoelectron Technology Co., Ltd. is a manufacturer specializing in optical communication equipment products.