SMC Networks 6750L2, Management Manual

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VLAN C
ONFIGURATION
2-43
in one or more VLANs, but the device at the other end of the link does
not support VLANs, then you must add this port as an untagged port (that
is, a port attached to a VLAN-unaware device).
VLAN Classification – When the switch receives a frame, it classifies
the frame in one of two ways. If the frame is untagged, the switch assigns
the frame to an associated VLAN (based on the PVID of the receiving
port. But if the frame is tagged, the switch uses the tagged VLAN ID to
identify the port broadcast domain of the frame.
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 by using
a Layer-3 router or switch.
Port-based VLANs – Port-based (or static) VLANs are manually 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
or flooding decisions, the switch must learn the relationship of the MAC
address to its related port—and thus to the VLAN—at run-time.
However, when GVRP is enabled, this process can be fully automatic.
Automatic VLAN Registration – GVRP (GARP VLAN Registration
Protocol) defines a system whereby the switch can automatically learn the
VLANs to which each endstation should be assigned. 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.