Allied Telesis AT-S29 - Manual (Page 122)

Advanced Topics
122
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
802.1Q 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).
Port-based VLANs are 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 and flooding decisions, the
switch learns the relationship of the MAC address to its related port-and
thus to the VLAN-at run-time.
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).
❑ If the frame is tagged, the switch uses the tagged VLAN ID to
identify the port broadcast domain of the frame.
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. Note that if you implement VLANs which do not overlap, but
still need to communicate, you must connect them using a router or
Layer 3 switch.