Understanding native VLAN

[dave cooper]

I am trying to understand native vlan and trunking

I have a server on with a trunk port with VLAN 10,11,12,20. I need to have VLAN 10 untagged, the rest of the VLANs tagged

Which Is this correct?

A)

switchport trunk encapsulation dot1q

switchport mode trunk

switchport trunk allowed vlan 10,11,12,20

switchport trunk native vlan 10

B)

switchport trunk encapsulation dot1q

switchport mode trunk

switchport trunk allowed vlan 11,12,20

switchport trunk native vlan 10

Does native lan have to be on the trunk?

Thanks

[InayathUlla Sharieff]

Hi Dave,

Yes the Native vlan 10 have to be on trunk interface if you want that to go as untagged. Else wen the vlan X is allowed on the trunk port those vlan goes as tagged. Hence when you mark the packet as native vlan then those vlan will forward out of the trunk port as untagged vlan.

NOTe: Make sure you have configured Native vlan X on both the switches on that trunk to avoid falling onto VLAN Leaking.

HTH

Regards

Inayath

*Plz rate all usefull posts.

[Reza Sharifi]

B is correct.  You don't need to add vlan 10 to the list of allowed vlans on the trunk since that is the native vlan.

B)

switchport trunk encapsulation dot1q

switchport mode trunk

switchport trunk allowed vlan 11,12,20

switchport trunk native vlan 10

HTH