7 Replies Latest reply: Feb 18, 2013 5:02 PM by Sathish Kumar RSS

    untagged and tagged vlan

    kevinlim62
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      Can someone explain to me what is meant by untagged vlan and tagged vlan? What is the difference between these two? Tq.

        • 1. Re: untagged and tagged vlan
          shafagh

          Cisco Trunk Port = Tagged (IEEE 802.1q tagging vlans and sending inside the trunk)

          Cisco Access Port = Untagged

          • 2. Re: untagged and tagged vlan
            kevinlim62

            Tagged vlan     = we tagged more than one vlan in the trunk port?

            Untagged vlan = we just configured the switchport as access port?

            • 3. Re: untagged and tagged vlan
              DelVonte

              Hi Kevin,

               

              All vlans, except the native VLAN when using 802.1Q, are tagged when trunking. Tagged means that the vlan information is added to the frame before it is sent over a trunk link. With 802.1Q the information is added to the frame directly. ISL encapsulates the frame with the VLAN information, and does not have a native VLAN, so all frames are tagged in this manner.

               

              HTH

              DelVonte

              • 4. Re: untagged and tagged vlan
                Jared

                According to the 802.1Q standard, the way to identify different vlans in a frame is by adding Vlan ID tag in the frame.  This tag identifies what vlan the frame is meant for.  If you want multiple vlans to pass via a switch interface, those vlans need to be tagged by configuring a trunk port on a cisco switch.

                 

                Access ports are typically untagged, meaning only one vlan passes via the interface.  There is also the case of the native vlan.  This is a vlan that is not tagged but other vlans that pass via the interface are tagged.

                 

                http://en.wikipedia.org/wiki/IEEE_802.1Q

                • 5. Re: untagged and tagged vlan
                  Rohan Jadhav

                  hi jared

                  native vlan in 802.1q are untagged

                  when there are multiple switches and all the switches having same native vlan such as vlan 1 . i have read that vlan id is added to frame so switch can identify the vlan of frame. But for native vlan , vlan id is not added to frame so how can switch identify, where to send the frame which has no vlan id tag

                  suppose there is a network consists of 5 switches, all the switches are connected , stp is running

                  2 switches are in 1 domain(has native vlan 3) and 3 switches are in different doamin(has native vlan 4).now how 802.1q will work

                  • 6. Re: untagged and tagged vlan
                    tnewshott

                    Rohan, please do not post to threads that are dormant for more than about six months. This thread had been dormant for two YEARS and two days.

                    • 7. Re: untagged and tagged vlan
                      Sathish Kumar

                      Can someone explain to me what is meant by untagged vlan and tagged vlan? What is the difference between these two?

                       

                      Vlan is a Virtual LAN. Switch will not break Broadcast Domain While using VLAN we can break broadcast domain.

                       

                      Switch having more than one vlan. if its same Vlan data can be pass through one vlan to another. if its different Vlan we need router or L3 Switch.

                       

                      Tagged VLAN means frame can be tagged which vlan that frame belongs to, that can be happen in trunk port of switch. Types of Trunk Tagging protocol 802.1Q and ISL and DTP.

                       

                      Untagged VLAN. Frame cant be tagged while travelling from one switch to another switch. Eg: VLAN1 Native Vlan or Management VLAN. Frame cant mention which vlan the frame belongs.