Configuring the Switch
3-88
Port Overlapping – Port overlapping can be used to allow access to commonly
shared network resources among different VLAN groups, such as file servers or
printers. Note that if you implement VLANs which do not overlap, but still need to
communicate, you can connect them by enabled routing on this switch.
Untagged VLANs – Untagged (or static) VLANs are typically used to reduce
broadcast traffic and to increase security. A group of network users assigned to a
VLAN form a broadcast domain that is separate from other VLANs configured on the
switch. Packets are forwarded only between ports that are designated for the same
VLAN. Untagged VLANs can be used to manually isolate user groups or subnets.
Forwarding Tagged/Untagged Frames
If you want to create a small port-based VLAN for devices attached directly to a
single switch, you can assign ports to the same untagged VLAN. However, to
participate in a VLAN group that crosses several switches, you should create a
VLAN for that group and enable tagging on all ports.
Ports can be assigned to multiple tagged or untagged VLANs. Each port on the
switch is therefore capable of passing tagged or untagged frames. When forwarding
a frame from this switch along a path that contains any VLAN-aware devices, the
switch should include VLAN tags. When forwarding a frame from this switch along a
path that does not contain any VLAN-aware devices (including the destination host),
the switch must first strip off the VLAN tag before forwarding the frame. When the
switch receives a tagged frame, it will pass this frame onto the VLAN(s) indicated by
the frame tag. However, when this switch receives an untagged frame from a
VLAN-unaware device, it first decides where to forward the frame, and then inserts a
VLAN tag reflecting the ingress port’s default VID.
Displaying Basic VLAN Information
The VLAN Basic Information page displays basic information on the VLAN type
supported by the switch.
Field Attributes
• VLAN Version Number* – The VLAN version used by this switch as specified
in the IEEE 802.1Q standard.
• Maximum VLAN ID – Maximum VLAN ID recognized by this switch.
• Maximum Number of Supported VLANs – Maximum number of VLANs that
can be configured on this switch.
* Web Only
Web – Click VLAN, 802.1Q VLAN, Basic Information.
