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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.
Untagged VLANs – Untagged (or static) VLANs are typically used
to reduce broadcast traffic and to increase security. A group of
network users assigned to a VLAN form a broadcast domain that is
separate from other VLANs configured on the switch. Packets are
forwarded only between ports that are designated for the same
VLAN. Untagged VLANs can be used to manually isolate user
groups or subnets. However, you should use IEEE 802.3 tagged
VLANs with GVRP whenever possible to fully automate VLAN
registration.
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.
To implement GVRP in a network, first add the host devices to the
required VLANs (using the operating system or other application
software), so that these VLANs can be propagated onto the
network. For both the edge switches attached directly to these
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