SMC Networks TigerSwitch SMC6948L2, Management Manual

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4-6
Forwarding Traffic with Unknown VLAN Tags
This switch only supports 256 VLANs with VLAN IDs from 1 to
2048, but the IEEE 802.1Q VLAN standard supports VLAN IDs of 1
to 4094. Therefore, if this switch is attached to endstations that
issue VLAN registration requests, it will have to forward unknown
VLAN tags. This traffic can only be propagated to the rest of the
network if automatic VLAN registration is enabled on your 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 decides where to
forward the frame, and then strips off the VLAN tag. However, to
forward a frame from a VLAN-unaware device to a VLAN-aware
device, the switch first decides where to forward the frame, and
then inserts a VLAN tag reflecting this port’s default VID. The
default PVID is VLAN 1 for all ports, but this can be changed (see
page 2-44 or page 3-29).