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  1. Hello Dionisis

    Yes you are correct in your description. Any traffic coming from the PC through the phone will be untagged and will go to the access VLAN configured on the port of the switch. All voice traffic is tagged and will go to the voice vlan configured on the port of the switch.

    Keep in mind that the voice vlan configuration not only configures the appropriate VLANs for data and voice, but also sends voice traffic with a QoS based on IEEE 802.1p CoS. In other words, a Quality of Service technique is automatically incorporated into the functionality of

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  2. Hello Abhishek

    In the past, before the advent of the switchport voice vlan command you would have to configure a port as a trunk port that included both the voice and data VLANs. It was around 10 years ago when I was first learning about Cisco IP telephony where we would use such a configuration. Back then, connections to IP phones were literally trunks.

    Today however, we use ports configured with voice VLANs. Such a port will have both the switchport mode access command as well as the switchport voice vlan command. So is this an access port or a trunk?


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  3. Hello Aniket

    Let me quote Rene from his lesson:

    This is the image he uses:


    Behind the scenes, we have a trunk between our switch and IP phone. The port on the IP phone that connects to the computer is an access port. The IP phone will forward all traffic from the computer to the switch untagged, traffic from the IP phone itself will be tagged. The only two VLANs that are allowed though, are the access and voice VLAN.

    So, all traffic to and from the phon

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  4. Thanks for the explanation Lazaros,
    However I have seen a working scenario wherein DATA VLAN is 135 & VOICE VLAN is 137, also switch port is not TRUNK, Native VLAN is 1. So how could DATA Vlan traffic will go untagged as DATA Vlan being 135… Also under switchport we are giving commnad as "Switchport mode access " for DATA vlan, then how can we put this interface in Trunk mode? (as per my understanding switchport would be either access or trunk port)

  5. Hello Aniket

    I think you had the same post on another thread, but that’s ok, cause I can add something here.

    If the native VLAN on a trunk is 1, then this VLAN will definitely function as the data VLAN in a scenario where a PC is connected to an IP phone co

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