VLAN usually facilitates communication between switches by dividing one button into two or more mini-switches. Thus, it allows administrators to make one switch to two virtual physically. These virtual switches will usually take the form of numbers-names. The traffic flows going to the switch port, thus, remain within the same virtual port without intersecting with others. It allows virtual switches to work just as if they were physical.
The switch ports and the traffic flow through the router are always dependent on the architecture of the building. Different floors can use traffic at different frequencies and in different quantities. It is usually recommended to use physically separate switches on each floor, especially if we are not talking about a home network and using the Internet but about administrative buildings where people constantly use traffic. A large amount of traffic is required to load complex sites and display complex tables. A VLAN can maintain its own unique MAC-address table and, in principle, guarantee non-mixing of traffic passing through the router (Tomsho, 2016). However, the best option would be to use different physical switches, which will be divided, for example, into offices on other floors. The VLAN can be divided into eight rooms on the fourth floor under different numbers, not necessarily sequential.
There is a VLAN extension backlink to two physical switches from one. In the design in question, this can be useful in practice where communication needs to exist between floors or even buildings (for instance, campus buildings). Then, even if the administrator originally installed physically different switches in the building, they will not interfere with creating this connection, no matter how far they are from each other. The VLAN extension allows people to ignore the usual topology rules: the access ports of each VLAN can be connected by the administrator. However, from the point of view of practice, it is more convenient to connect the VLAN through a third foreign port called the trunk port.
Reference
Tomsho, G. (2016). Guide to networking essentials (7th ed.). Boston, MA: Cengage Learning.