Allied Telesis AT-S62 - Manual (Page 390)

Chapter 20: Tagged and Port-based Virtual LANs
Section V: Virtual LANs 390
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-S62
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.
General Rules
for 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, each part of the VLAN
on the different switches should 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 automatically assigned by the AT-S62
management software.
❑ A port-based 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.
❑ 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 of
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. The introduction of a router into your network
could create security issues from unauthorized access to your
network.
❑ A VLAN that spans several switches requires a port on each switch
for the interconnection of the various parts of the VLAN. For
example, a VLAN that spans three switches would require one
port on each switch to interconnect the various sections of the
VLAN. In network configurations where there are many individual