Use of Native VLAN in AP connecting Trunk Switchport

[nips]

Hi All,

I need to have the proper understanding of the use of Native VLAN in the  trunk switchport an Access point is connecting.

My current understanding is the AP can not read DHCP IP address via a tagged port (can not read 802.1Q packets).Therefore the management VLAN is setting as Native VLAN.

Based on this understanding (if the AP can not read 802.1Q packets) how the user traffic which are tagged, identified by  the AP and pass those packets to the relevant user.

I need to clear these confusions and want to know actual behavior with the native vlan. Hope your expertise answers.

Thank you

[Flavio Miranda]

@nips 

 Your understanding is correct. The AP is actually able to tag, otherwise it would not be possible to segragate SSID per VLAN. But, for management traffic like DHCP the AP need to receive it untagged and that´s why we need at least one vlan untagged on the trunk(native vlan)

[nips]

Thank you @Flavio Miranda , 

But my twist is if the AP can tag and read 802.1Q packets why only the tagged management traffic can not read ?

[Flavio Miranda]

That´s something only Cisco could tell us. They built the AP like this, it does not understand tag on the management traffic but it does on the user traffic. Another way to put it is the AP understand tag on data plane but not on the control plane.

 Go figure. However, as long as you keep the management vlan as native, you will be fine

[MHM Cisco World]

AP with local mode not need any vlan so it not need any trunk that why it need to use native vlan to connect to SW

AP flex need trunk since it mapped wlan-vlan for ssid 

So there are two case

MHM

[nips]

Thank you @MHM Cisco World 

[Haydn Andrews]

If in flex mode you can also define the native vlan in the flex profile on the WLC.

I always make management native and trunk the rest