802.1Q VLAN Configuration
There are up to 256 configurable VLAN groups. By default when 802.1Q is enabled, all ports on the switch belong to default VLAN (VID 1). The default VLAN cannot be deleted.
Understand nomenclature of the Switch
Tagging and Untagging
Every port on an 802.1Q compliant switch can be configured as tagging or untagging.
。Tagging: 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
。Untagging: 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
Frame Income | Income Frame is tagged | Income Frame is untagged | |
Frame Leave | |||
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Leave port is tagged | Frame remains tagged | Tag is inserted | |
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Leave port is untagged | Tag is removed | Frame remain untagged | |
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Here pay attention to the explainion of “Access”, ”Always Untag”and “Trunk”.
。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
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.
。Always Untag: The port belongs to VLANs, and each VLAN is