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Q in Q on client side

Utair Corporation


Is it possible to configure trunk interface to be Q in Q on client side, so all client packets get tagged twice?

Here is our situation - our service provider gave us several VLANS and we are using dot1q trunks with them. But, since it's different organization, we do not want to participate in their VTP and also we want to have independent VLAN database.

In general, we could, of course set up intermidiate swithes at each point and pretend they are provider swithes and create classic scheme, but that would be waste of dosen switches.

3 Replies 3


Looks that QinQ would be useful for the described request,

QinQ would have to be configured on the switch interface facing the provider link.

One VLAN of the client LAN would be used to transport the provider trunk.

QinQ would be needed to configured on the exit interface of the customer LAN network.

Basically all provider VLANs are transported over a single VLAN of the customer network.

One thing to keep in mind is that the switches in customer VLAN must be QinQ capable, and the MTU setting should be raised at the switch level.

One example config of ingress/egress port:

interface Gigabit 0/1

description QinQ port

switchport access vlan 99 ! (vlan used on custmer LAN to transport QinQ)

switchport mode dot1q-tunnel

Basically all provider VLANs are transported over a single VLAN of the customer network.

I don't need to transport provider's VLANs. I need to transport my VLANs over one provider's VLAN.

Problem is that provider's switches do not support QinQ, they could just increase MTU.

One solution is to install intermideate switch, which will pretend to be provider's, but that's a waste of hardware.

The service provider setup described is quite different of a tradition LAN extension service.

With the LAN extension service is possible to send tagged and untagged traffic through the link.

How is the line delivered? with Ethernet RJ45 at both ends? You have one physical port per VLAN? Or one port with some number of VLANs enabled? If this is the case, can you map VLAN numbers of you LAN with providers VLANs?

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