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1 assigning ports to vlans, 1 vlan classification, 2 port overlapping – Planet Technology WGS3-2620 User Manual

Page 248: 3 port-based vlans, 4 automatic vlan registration (gvrp)

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WGS3 Layer 3 Switch User’s Manual

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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.