Allied Telesis AT-S63 - Manual (Page 431)

AT-S63 Management Software Menus Interface User’s Guide
Section III: VLANs 431
recognize and forward frames belonging to the same VLAN even though
the VLAN spans multiple switches.
For example, if you had a port-based VLAN titled Marketing that
spanned three AT-9400 Series switches, you would assign the Marketing
VLAN on each switch the same VID.
You can assign this number manually or allow the AT-S63 management
software to do it automatically. If you allow the management software to
do it automatically, it selects the next available VID. This is acceptable
when you are creating a new, unique VLAN.
If you are creating a VLAN on a switch that will be part of a larger VLAN
that spans several switch, then you will need to assign the number
yourself so that the VLAN has the same VID on all switches.
Untagged Ports You need to specify which ports on the switch are to be members of a
port-based VLAN. Ports in a port-based VLAN are referred to as untagged
ports and the frames received on the ports as untagged frames. The
names derive from the fact that the frames received on a port will not
contain any information that indicates VLAN membership, and that
VLAN membership will be determined solely by the port’s PVID. (There is
another type of VLAN where VLAN membership is determined by
information within the frames themselves, rather than by a port’s PVID.
This type of VLAN is explained in ”Tagged VLAN Overview” on page 436.)
A port on a switch can be an untagged member of only one port-based
VLAN at a time. An untagged port cannot be assigned to two port-based
VLANs simultaneously.
Port VLAN
Identifier
Each port in a port-based VLAN must have a port VLAN identifier (PVID).
The switch associates a frame to a port-based VLAN by the PVID
assigned to the port on which the frame is received, and forwards the
frame only to those ports with the same PVID. Consequently, all ports of
a port-based VLAN must have the same PVID. Additionally, the PVID of
the ports in a VLAN must match the VLAN’s VID.
For example, if you were creating a port-based VLAN on a switch and
you had assigned the VLAN the VID 5, the PVID for each port in the VLAN
would need to be assigned the value 5.
Some switches and switch management programs require that you
assign the PVID value for each port manually. However, the AT-S63
management software performs this task automatically. The software
automatically assigns a PVID to a port, making it identical to the VID of
the VLAN to which the port is a member, when you assign the port as an
untagged member to a VLAN.