GE DS-82 - Manual (Page 75)

Chapter 4: Web-Based Management
GE-DS-82 and 82-PoE Ethernet Managed Switch User Manual 71
NOTE: All unselected ports are treated as belonging to another single VLAN. If the
port-based VLAN is enabled, the VLAN-tagging is ignored.
802.1Q VLAN
Tagged-based VLAN is an IEEE 802.1Q specification standard. Therefore, it is possible
to create a VLAN across devices from different switch venders. IEEE 802.1Q VLAN
uses a technique to insert a "tag" into the Ethernet frames. Tag contains a VLAN
Identifier (VID) that indicates the VLAN numbers.
You can create and delete Tag-based VLAN. There are 256 VLAN groups to provide
configure. Enable 802.1Q VLAN, the all ports on the switch belong to default VLAN,
VID is 1. The default VLAN can't be deleting.
Understand nomenclature of the Switch
• IEEE 802.1Q Tagged and Untagged
Every port on an 802.1Q compliant switch can be configured as tagged or untagged.
Tagged Ports with tagging enabled will put the VID number, priority and other VLAN information
into the header of all packets that flow into those ports. If a packet has previously been
tagged, the port will not alter the packet, thus keeping the VLAN information intact. The
VLAN information in the tag can then be used by other 802.1Q compliant devices on the
network to make packet-forwarding decisions.
Untagged Ports with untagging enabled will strip the 802.1Q tag from all packets that flow into
those ports. If the packet doesn't have an 802.1Q VLAN tag, the port will not alter the
packet. Thus, all packets received by and forwarded by an untagging port will have no
802.1Q VLAN information. (Remember that the PVID is only used internally within the
Switch). Untagging is used to send packets from an 802.1Q-compliant network device to
a non-compliant network device.
Frame Income
Frame Leave
Income Frame is tagged Income Frame is untagged
Leave port is tagged Frame remains tagged Tag is inserted
Leave port is untagged Tag is removed Frame remain untagged