Cabletron Systems 9032578-02 Benutzerhandbuch

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MAC address based

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Protocol based 

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Subnet based 

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Multicast based 

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Policy based 

Detailed information about these types of VLANs is beyond the scope of this manual. 
Each type of VLAN is briefly explained in the following subsections.

Ports of L2 devices (switches, bridges) are assigned to VLANs. Any traffic received by a 
port is classified as belonging to the VLAN to which the port belongs.  For example, if 
ports 1, 2, and 3 belong to the VLAN named “Marketing”, then a broadcast frame received 
by port 1 is transmitted on ports 2 and 3.  It is not transmitted on any other port.

In this type of VLAN, each switch (or a central VLAN information server) keeps track of 
all MAC addresses in a network and maps them to VLANs based on information 
configured by the network administrator.  When a frame is received at a port, its 
destination MAC address is looked up in the VLAN database, which returns the VLAN to 
which this frame belongs.

This type of VLAN is powerful in the sense that network devices such as printers and 
workstations can be moved anywhere in the network without the need for network 
reconfiguration.  However, the administration is intensive because all MAC addresses on 
the network need to be known and configured.

Protocol-based VLANs divide the physical network into logical VLANs based on 
protocol.  When a frame is received at a port, its VLAN is determined by the protocol of 
the packet.  For example, there could be separate VLANs for IP, IPX and Appletalk.  An IP 
broadcast frame will only be sent to all ports in the IP VLAN.

Subnet-based VLANs are a subset of protocol based VLANs and determine the VLAN of a 
frame based on the subnet to which the frame belongs.  To do this, the switch must look 
into the network layer header of the incoming frame.  This type of VLAN behaves similar 
to a router by segregating different subnets into different broadcast domains.