Allied Telesis AT-S25 - Manual (Page 120)

Section II: Local and Telnet Mangement
120
General Rules
to Creating a
Port-based
VLAN
Below is a summary of the general rules to observe when creating a port-
based VLAN.
❑ Each port-based VLAN must be assigned a unique VID. If a
particular VLAN spans multiples switches in a stack, each port of
the VLAN on the different switches must be assigned the same
VID.
❑ A port can be an untagged member of only one port-based VLAN
at a time.
❑ Each port must be assigned a PVID. This value must be the same
for all ports in a port-based VLAN and it must match the VLAN’s
VID. This value is assigned automatically by the AT-S25
management software.
❑ 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.
Drawbacks to
Port-based
VLANs
There are several drawbacks to port-based VLANs:
❑ It is not easy to share network resources, such as servers and
printers, across multiple VLANs. A router or Layer 3 switch must be
added to the network to provide a means for interconnecting the
port-based VLANs.
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, assume that you were creating a port-
based VLAN on a switch and you had assigned the
VLAN the VID 5. Consequently, 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-S25 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.
PARAMETER DESCRIPTION