Allied Telesis AT-S82 - Manual (Page 46)

Chapter 6: VLANs
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The VLAN tag information in the header of the frame is stripped from the
frame’s header if the tag matches the PVID of the port (an untagged
member of the VLAN). These frames are untagged after transmission from
the switch.
Guidelines for
Creating a VLAN
The following list provides guidelines for creating a VLAN:
ˆ Each VLAN must be assigned a unique VID. If a particular VLAN
spans multiples switches, each part of the VLAN on the different
switches should be assigned the same VID.
ˆ A port can be an untagged member of only one VLAN at a time and
can receive both tagged and untagged packets.
ˆ If you want a port to be an untagged member of a different VLAN, you
must first modify the VLAN (usually the default VLAN) where the port
is an untagged member. First, delete that port from the original VLAN
and then assign the port to another VLAN as an untagged port.
ˆ A VLAN that spans multiple switches requires a port on each switch
where the VLAN is located to function as an interconnection between
the switches where the various parts of the VLAN reside.
This port may be defined as an untagged member of a VLAN where
the port is connected to another switch via another untagged port
member of the VLAN. This means that all traffic on this inter-switch
port contains traffic for that VLAN only.
Another scenario is where the port could be an untagged member of
one VLAN and a tagged member of one or more VLANs. The port
would then be connected to another switch via a port with the same
VLAN membership. This means that the traffic on this inter-switch port
is for any or all of the VLANs of which the port is a member.
ˆ If there are end nodes in different VLANs that need to communicate
with each other, a router or Layer 3 switch is required to interconnect
the VLANs.
The switch can support up to 255 VLANs.