SmartSwitch Router User Reference Manual 23Chapter 3: Bridging Configuration Guide• Multicast based• Policy basedDetailed information about these types of VLANs is beyond the scope of this manual.Each type of VLAN is briefly explained in the following subsections.Port-based VLANsPorts of L2 devices (switches, bridges) are assigned to VLANs. Any traffic received by aport is classified as belonging to the VLAN to which the port belongs. For example, ifports 1, 2, and 3 belong to the VLAN named “Marketing”, then a broadcast frame receivedby port 1 is transmitted on ports 2 and 3. It is not transmitted on any other port.MAC-address-based VLANsIn this type of VLAN, each switch (or a central VLAN information server) keeps track ofall MAC addresses in a network and maps them to VLANs based on informationconfigured by the network administrator. When a frame is received at a port, itsdestination MAC address is looked up in the VLAN database. The VLAN databasereturns the name of the VLAN to which this frame belongs.This type of VLAN is powerful in the sense that network devices such as printers andworkstations can be moved anywhere in the network without the need for networkreconfiguration. However, the administration is intensive because all MAC addresses onthe network need to be known and configured.Protocol-based VLANsProtocol-based VLANs divide the physical network into logical VLANs based onprotocol. When a frame is received at a port, its VLAN is determined by the protocol ofthe packet. For example, there could be separate VLANs for IP, IPX and Appletalk. An IPbroadcast frame will only be sent to all ports in the IP VLAN.Subnet-based VLANsSubnet-based VLANs are a subset of protocol based VLANs and determine the VLAN of aframe based on the subnet to which the frame belongs. To do this, the switch must lookinto the network layer header of the incoming frame. This type of VLAN behaves similarto a router by segregating different subnets into different broadcast domains.
