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Port-based VLANs are tied to specific ports. The switch's
forwarding decision is based on the destination MAC address and
its associated port. Therefore, to make valid forwarding and
flooding decisions, the switch learns the relationship of the MAC
address to its related port—and thus to the VLAN—at run-time.
When the switch receives a frame, it assigns the frame to the port's
default VLAN if the frame is untagged (determined by the PVID of
the receiving port), or maps it for output to the broadcast domain
associated with the frame's VLAN tag.
Port Overlapping
Port overlapping can be used to allow access to commonly shared
network resources among different VLAN groups, such as file
servers or printers. Note that if you implement VLANs which do
not overlap, but still need to communicate, you can connect them
using the Layer 3 switch or router.
Automatic VLAN Registration (GVRP)
GVRP defines a system whereby the switch can automatically learn
the VLANs each endstation should be assigned to. If an endstation
(or its network adapter) supports the IEEE 802.1Q VLAN protocol,
it can be configured to broadcast a message to your network
indicating the VLAN groups it wants to join. When this switch
receives these messages, it will automatically place the receiving
port in the specified VLANs, and then forward the message to all
other ports. When the message arrives at another switch that
supports GVRP, it will also place the receiving port in the specified
VLANs, and pass the message on to all other ports. VLAN
requirements are propagated in this way throughout the network.
This allows GVRP-compliant devices to be automatically
configured for VLAN groups based solely on endstation requests.
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