VLAN is a broadcast domain, so you can be segmenting Ethernet broadcast domains with VLANs. Network ports might be configured with one (access or untagged mode) or multiple VLANs (trunk or tagged mode).

802.1Q trunking modifies Ethernet frames to add a numeric tag. Using this tag can forward frames to different VLANs. Native VLAN is the untagged VLAN on an 802.1Q trunked switch port. VMware vSphere supports external VLAN tagging (only at physical switch level), virtual switch VLAN tagging, and VM VLAN tagging.

All of this from the total basic networking, we will describe in the next part.