You can configure a port in two ways, as an access port or a trunk port. When talking about VLAN, a trunk is a link (a port) that carries traffic for multiple VLANs. However, we have a better way to propagate VLANs between switches: trunks. Instead, center switch uses a trunk with right switch to carry multiple VLANs on a single link. The switch on the center must use the same VLAN on that link. The switch on the left has the blue VLAN on the interface toward the switch on the center. To do that, you need to be sure that the port of a switch used to connect to another switch has the same VLAN on both switches. You can also configure the same VLANs on multiple switches, connect them together, and have the same VLAN to propagate on multiple switches. Instead, VLAN 1 is the default VLAN: all the ports of a switch are in that VLAN by default. You cannot remove nor edit them, and you will (almost) never need them. VLANs 1002-1005 are used to emulate a token ring, a legacy feature. Instead, we will use the normal range, VLANs from 1 to 1005 (note that VLAN 0 is not available). However, VLANs after 1005 are part of the “extended range” and we won’t use them, at least for this article. This means that you will be able to use up to 4094 VLANs on a switch. You can identify VLANs by their VLAN ID, a number ranging from 1 to 4094. In this picture, the two PCs on the green side share the same broadcast domain, which differ from the one shared by the two PCs on the light-blue side The details Consequently, devices connected to ports in the same VLANs can talk directly, while inter-VLAN communication requires a router. You can configure the switch to have some ports in a VLAN and some ports in another. However, VLANs alone are useless: you need to assign them to ports. In other words, you are able to create or delete VLANs at will. Provided that, the powerful thing about VLANs is that they are under complete control of the administrator. As a result, two devices in two different VLANs need a router to talk between one another, as they cannot do it directly. Specifically, each VLAN is an independent broadcast domain. VLAN stands for Virtual Local Area Network, and it is a technology to divide your network into segments. It is time to start! Some Theory about VLANs and Trunks What are VLANs?