dot1q tunnel

Unanswered Question
Aug 28th, 2008
User Badges:

We use following command for QinQ(dot1q tunneling).

interface GigabitEthernet2/0/8

switchport access vlan 75

switchport mode dot1q-tunnel

what ever the packet coming into this port will be tagged with vlan 75 as outer vlan.

But my requirment deffers slitly from this. I need to have an dot1q tunnel port for a range of vlans. For remaining vlans the port should act as trunk port (only allowing the tagged packet, no outer vlan tagging).



  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
guruprasadr Thu, 08/28/2008 - 01:59
User Badges:
  • Gold, 750 points or more

HI Senthil, [Pls Rate if HELPS]

Here are some Guidelines & Restrictions:

1. Dedicate one VLAN for each tunnel.

2. Assign only tunnel ports to VLANs used for tunneling.

3. Trunks require no special configuration to carry tunnel VLANs.

4.Tunnel ports are not trunks. Any commands to configure trunking are inactive while the port is configured as a tunnel port.

With Reference to Point #4, The ports that are enabled with "switchport mode dot1q-tunnel" will not work as Normal Switch TRUNK.

Hope I am Informative.


Best Regards,

Guru Prasad R

Giuseppe Larosa Thu, 08/28/2008 - 02:25
User Badges:
  • Super Silver, 17500 points or more
  • Hall of Fame,

    Founding Member

Hello Senthi,

vlan 75 will be the customer Vlan id.

dot1q tunnel introduces a double 802.1Q tag with external having vlan-id field 75.

The port connecting to the dot1q tunnel can be a trunk : the end results will be that all VLans permitted and in forwarding state on CE trunk port will be carried with a stack of 802.1Q tags [75 X]

No selection on what vlans to be tunneled can be done.

If you want to have some vlans not tunneled you need to carry them on a separate port to a different service provider switch port.

(this is for efficiency of the dot1q tunnel)

Hope to help



This Discussion