GE -DSH-73 User Manual page 87

• 802.1Q VLAN Port Configuration
This page is used for configuring the Industrial Switch port VLAN. The VLAN per Port
Configuration page contains fields for managing ports that are part of a VLAN. The
port default VLAN ID (PVID) is configured on the VLAN Port Configuration page. All
untagged packets arriving to the device are tagged by the ports PVID.
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
(Trunk Link)
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
(Access Link)
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
Here pay attention to the explaining of "Access", "Trunk" and "Hybrid".
• Access: Ports will strip the 802.1Q tag from all packets that out of 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. Untagging is used to send packets from an 802.1Q-
compliant network device to a non-compliant network device.
Ports with "Access" mode belong to a single untagged VLAN.
• Trunk: Ports with tagging enabled will put the VID number, priority and other VLAN
information into the header of all packets that out of 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.
GE-DSH-73/DSH-82 and DSH-82-PoE User Manual
Income Frame is tagged
Frame remains tagged
Tag is removed
Chapter 5: Web-Based Management
Income Frame is untagged
Tag is inserted
Frame remain untagged
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