Enterasys 1805 User Guide
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Virtual LANs (VLANs) 93
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, but this can be changed (see “802.1Q VLAN
Figure B-1. Multi-Switch VLAN Configuration
Forwarding Traffic with Unknown VLAN Tags
Up to 2048 VLANs are supported by the IEEE 802.1Q standard, but this
switch only supports 16 VLANs. Therefore, if this switch is attached to any
device that forwards frames with unknown VLAN tags, or to endstations
which issue VLAN registration requests for unknown VLANs, this traffic
will be dropped.