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I have to go through and find out the configuration set up on the old Dell Force10 switches that we have. I was wanting to make sure that I fully understand what is going on with what I see. I have the configuration of the VLANs for the ports below:

VLAN Config IDF3

I am just trying to fully understand what this all means. I know that the U is for untagged and that T is for tagged. The question that I have is what the meaning of untagged and tagged has on the ports. I thought that if the port is in use you would want to tag that port with the VLAN that you want it to be on. But I know that untagged is what is getting used because I know they are physically plugged.

So, I am just a little confused. If someone could please help me understand.

Thank you

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The meaning of "tagged" and "untagged" is this:

If a VLAN is tagged on a port, it means that data from that VLAN is sent out the port in 802.1q format, which has a VID (a tag) that identifies what VLAN it's associated with. Also, data received with a VLAN tag is placed in the appropriate VLAN.

If the VLAN is untagged, it is sent in "standard" 802.3 Ethernet, with no VLAN information. Data received on the port in "standard" format is placed into this VLAN.

Note that a port can have only one untagged VLAN, but multiple tagged VLANs.

A VLAN can be untagged on one port, but tagged on another.

In the Cisco world, an untagged VLAN is called the "native VLAN."

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  • Oh ok. See that is where my confusion comes in. The switches that we have now are Dell Force10 configured on the command line, and we are switching to the Meraki brand switches that uses a website interface. The Meraki web interface does not use tagging and untagging. If you configure the trunk port, you have the option of native and allowed VLANs, I assume that allowed is where you would list all of the VLANs that need to be communicated on this switch, but what is the Native VLAN and the use for that. Then the other port configuration would be access and you just type in the VLAN you want
    – Justin Lubbers
    Commented Nov 20, 2015 at 16:47
  • The native vlan is the untagged vlan
    – Ron Trunk
    Commented Nov 20, 2015 at 18:02
  • I am still confused on the using of untagged and tagged, does that just mean the format that you want the VLAN to run. When I heard untagged and tagged I thought that it was going to reference that if you wanted to have gi0/1 to be on VLAN 100, you would want to tag VLAN 100 to that port. But why is the native VLAN only on the trunk and what is the use of it for the access ports?
    – Justin Lubbers
    Commented Nov 20, 2015 at 20:37
  • By definition, an access port has only one VLAN and it is untagged (native). Only trunk ports can have more than one VLAN -- zero or one can be untagged (native), while all the rest must be tagged. If you want VL 100 on a port, you must decide if you want to send it tagged or untagged-- that is, 802.1q format or 802.3 format. Most end hosts only understand 802.3, i.e. untagged format.
    – Ron Trunk
    Commented Nov 21, 2015 at 3:49

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