Any broadcast or multicast packets originating from a member of a VLAN will be flooded only among the members of that VLAN. Communication between VLANs, however, must go through a router.
The following figure illustrates how communication occurs between geographically dispersed VLAN members.
In this figure, VLAN 10 (Engineering), VLAN 20 (Marketing), and VLAN 30 (Finance) span three floors of a building. If a member of VLAN 10 on Floor 1 wants to communicate with a member of VLAN 10 on Floor 3, the communication occurs without going through the router, and packet flooding is limited to port 1 of Switch 2 and Switch 3 even if the destination MAC address to Switch 2 and Switch 3 is not known.
