Allied Telesis AT-S25 - Manual (Page 122)

Section II: Local and Telnet Mangement
122
❑ 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.
❑ The introduction of a router into your network could create
security issues from unauthorized access to your network.
❑ A VLAN that spans several stacks of switches will require 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 VLANs that span switches, many ports can end up
being used ineffectively just to interconnect the various VLANs.