Port Overlapping; Forwarding Tagged/Untagged Frames; Automatic Vlan Registration - Dell PowerConnect 5224 System User's Manual

belongs.

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. If you
implement VLANs that do not overlap but still need to communicate, you must connect them using a router or Layer 3 switch.

Forwarding Tagged/Untagged Frames

Ports can be assigned to multiple tagged or untagged VLANs. Each port on the switch is, therefore, capable of passing tagged or untagged frames. To forward
a frame from a VLAN-aware device to a VLAN-unaware device, the switch first determines where to forward the frame. The switch then strips off the VLAN tag.
However, to forward a frame from a VLAN-unaware device to a VLAN-aware device, the switch first determines where to forward the frame. It then inserts a
VLAN tag reflecting this port's default VID. The default port VLAN ID is 1, but it can be changed from the VLAN Port Settings page.

Automatic VLAN Registration

GARP VLAN Registration Protocol (GVRP) defines a way for switches to exchange VLAN information to automatically register VLAN members on ports across the
network.
GVRP uses GVRP Bridge Protocol Data Units (GVRP BPDUs) to advertise static VLANs to other switches in the network. Any GVRP-enabled device receiving the
advertisements can dynamically join the advertised VLAN. All GVRP-dynamically learned VLANs operate as tagged VLANs. A GVRP-enabled port only joins a
VLAN when an advertisement for that VLAN is received on that specific port. A GVRP-enabled port forwards advertisements from other ports on the switch but
does not join the advertised VLAN.
Hosts, such as computers and servers, can be connected to switch ports that are part of a statically configured VLAN. If GVRP is enabled on the switch, these
VLANs are advertised to the rest of the network. If a host (or its network adapter) supports GVRP, it can directly indicate the VLAN groups that it is supposed
to join. When the attached GVRP-enabled switch receives the VLAN advertisements, it automatically places the receiving port in the specified VLANs and then
forwards the advertisements to all other ports. When the advertisements arrive at another GVRP-enabled switch, the switch places the receiving port in the
specified VLANs, and passes the advertisements on to all other ports. As a result, VLAN requirements are spread throughout the network, which allows GVRP-
compliant devices to be automatically configured for VLAN groups based solely on host requests.
The following figure shows how GVRP can propagate VLANs across a network.