GE -DS-242-POE User Manual page 65

Understanding the 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
Leave port is tagged
Leave port is
untagged
VLAN Group Configuration
• VLAN Group Configuration
Figure 4-27: VLAN Group Configuration interface
GE-DS-242-PoE Managed Ethernet Switch User Manual
Income Frame is tagged
Frame remains tagged
Tag is removed
Chapter 4: Web-Based Management
Income Frame is untagged
Tag is inserted
Frame remain untagged
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