Allied Telesis AT-S63 User Manual

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Chapter 24: Multiple VLAN Modes
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Section VI: Virtual LANs
Non-802.1Q Compliant Multiple VLAN Mode
Unlike the 802.1Q-compliant VLAN mode, which isolates port traffic by 
placing each port in a separate VLAN, this mode forms one VLAN with a 
VID of 1 that encompasses all ports. To establish traffic isolation, it uses 
port mapping. The result, however, is the same. Ports are permitted to 
forward traffic only to the designated uplink port and to no other port, even 
when they receive a broadcast packet.
Another difference with this mode is that the uplink port is untagged. 
Consequently, you would use this mode when the device connected to the 
uplink port is not IEEE 802.1Q compatible, meaning that the device cannot 
handle tagged packets.
Note
When the uplink port receives a packet with a destination MAC 
address that is not in the MAC address table, the port broadcasts 
the packet to all switch ports. This can result in ports receiving 
packets that are not intended for them. 
Also note that a switch operating in this mode can be remotely 
managed through any port on the switch, not just the uplink port.