3-6
Port-based VLAN
The packets that a switch receives and identifies as belonging to a port-based VLAN are
forwarded only over the ports assigned to that VLAN. Ports not selected as belonging to a VLAN
are treated as if they belong to another single VLAN. Port based VLAN’s are limited to the ports
of a single switch and do not allow membership to cross boundaries into other switches, as with
tag-based VLAN’s. Further, if a port-based VLAN is enabled, any VLAN-tagging will be ignored.
1. Click
Add
to add a new VLAN group.
2. Enter a VLAN group name, group IP, and then select the members for this VLAN group.
3. Click
on
Apply
to adopt the settings.
4. Next, you will see your VLAN group displayed.
5. If the group list is longer than one page, you can click
Next Page
to view other VLAN groups.
6. Use
the
Delete
button to delete any unwanted VLAN’s.
7. Use
the
Edit
button to modify the existing VLAN’s.
Note:
Always remember to select
Save Configuration
to save your settings. Otherwise, the
settings you made will be lost when the switch is powered off.
Because the port-based VLAN is defined on the switch itself and does not use information
contained in the packet frame to define its membership, it is restricted to ports of the same switch.
Effectively, only the switch itself knows the architecture of a port-based VLAN, while the
segments connected to the switch ports have no way of knowing the VLAN definition even exists.
This is the key difference between port and tag based Virtual LAN’s.
802.1Q VLAN
This tag-based VLAN is an IEEE 802.1Q standard, which allows VLAN’s to be created across
different switches (see Figure 1). IEEE 802.1Q tag-based VLAN’s make use of VLAN control
information stored in a VLAN header attached to IEEE 802.3 packet frames. This tag contains a
VLAN Identifier (VID) that indicates which VLAN a frame belongs to. Since a switch only has to
check a frame’s tag, without the need to dissect the contents of the frame, this also saves a lot of
computing resources within the switch.
Figure.1 Tagged VLAN
