Facts about VLANs

1. Even if two nodes share a common IP subnet, they will not be able to directly communicate if they are in separate VLANs.
2. Any inter-VLAN traffic must first traverse a layer-3 device such as a router in order to communicate with another VLAN.
3. If the ingress interface (the interface on which a frame arrives) is configured as a member of an untagged VLAN, the switch will strip off the frame’s tag before transmitting it. On the other hand, if the interface is configured as a member of a tagged VLAN (for example, if the interface is part of a trunk link between switches), the switch will not remove the frame’s tag before transmitting it.