Planet Technology WGS3-404 - Manual (Page 248)

WGS3 Layer 3 Switch User’s Manual - 240 -
6.3.1 Assigning Ports to VLANs
Before enabling VLANs for the switch, you must first assign each port to the VLAN group(s) it will
participate in. By default all ports are assigned to VLAN 1 as untagged ports. Add a port as a tagged port
(that is, a port attached to a VLAN-aware device) if you want it to carry traffic for one or more VLANs and
the device at the other end of the link also supports VLANs. Then assign the port at the other end of the
link to the same VLAN(s). However, if you want a port on this switch to participate 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).
6.3.1.1 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.
6.3.1.2 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. (Not supported for multilayer mode of WGS3-2620) Note
that if you implement VLANs which do not overlap, but still need to communicate, you can connect them
by setting this switch to multilayer mode, and assigning an IP interface address to the different VLANs.
(See “Connecting VLAN Groups”)
6.3.1.3 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 automated.
6.3.1.4 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.