Introduction to port-based VLAN

Port-based VLANs group VLAN members by port. A port forwards traffic for a VLAN only after it is assigned to the VLAN.

Port link type

You can configure the link type of a port as access, trunk, or hybrid. The link types use the following VLAN tag handling methods:

∙An access port belongs to only one VLAN and sends traffic untagged. It is usually connects to a user device unable to recognize VLAN tagged-packets or when there is no need to separate different VLAN members.

∙A trunk port can carry multiple VLANs to receive and send traffic for them. Except traffic from the port VLAN ID (PVID), traffic sent through a trunk port will be VLAN tagged. Usually, ports connecting network devices are configured as trunk ports.

∙Like a trunk port, a hybrid port can carry multiple VLANs to receive and send traffic for them. Unlike a trunk port, a hybrid port allows traffic of all VLANs to pass through VLAN untagged. Usually, hybrid ports are configured to connect devices whose support for VLAN tagged-packets you are uncertain about.

PVID

By default, VLAN 1 is the PVID for all ports. You can change the PVID for a port as required. Use the following guidelines when configuring the PVID on a port:

∙An access port can join only one VLAN. The VLAN to which the access port belongs is the PVID of the port. The PVID of the access port changes along with the VLAN to which the port belongs.

∙A trunk or hybrid port can join multiple VLANs, and you can configure a PVID for the port.

The following table shows how ports of different link types handle frames:

Port type

Actions (in the inbound direction)

Actions (in the outbound direction)

 

Untagged frame

 

Tagged frame

 

Access

Tags the frame

with

∙ Receives the frame if its

Removes the VLAN tag and sends the

 

the PVID tag.

 

VLAN ID is the same as

frame.

 

 

 

the PVID.

 

 

 

 

∙ Drops the frame if its

 

 

 

 

VLAN ID is different

 

 

 

 

from the PVID.

 

 

 

 

 

 

Trunk

Checks whether

the

∙ Receives the frame if its

∙ Removes the tag and sends the

 

PVID is carried on the

VLAN is carried on the

frame if the frame carries the PVID

 

port:

 

port.

tag and the port belongs to the PVID.

 

∙ If yes, tags the

∙ Drops the frame if its

∙ Sends the frame without removing

 

frame with the

VLAN is not carried on

the tag if its VLAN is carried on the

 

PVID tag.

 

the port.

port but is different from the PVID.

Hybrid

∙ If not, drops the

 

Sends the frame if its VLAN is carried on

 

frame.

 

 

the port. The frame is sent with the VLAN

tag removed or intact depending on your configuration.

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