Adtran Netvanta 3205 router and VLAN tagging

tnisupport used Ask the Experts™
I have a customer that was given 2 Adtran Netvanta 3205's from their carrier to truncate a T1 connection between 2 of their offices.

The T1 WAN connection is working and we have some connectivity between the routers (via the WAN network which is a /30 as a ppp interface).

In configuring the main Ethernet interface (Eth 0/1) to use 802.1q encapsulation and configuring sub-interfaces, I'm trying to confirm that:

interface eth 0/1.11
 vlan-id 11
 ip address
 no shutdown

means that this particular sub-interface is assigned a VLAN of 11 and is being tagged.

For further acknowledgement, does an additional sub-interface configured as:

interface eth 0/1.25
 vlan-id 25 native
 ip address
 no shutdown

mean this is the default VLAN of 25 and is NOT being tagged?

As well, do I have to include or do anything with the PPP/T1 interface as far as VLAN tagging (similar to above) to get traffice to flow through to the other side?

I need to be able to pass other tagged VLAN's between and through each side for both data and voice.

I've also been trying to find a configuration manual for this unit, but can't seem to find that either.
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Michael OrtegaSales & Systems Engineer

"...means that this particular sub-interface is assigned a VLAN of 11 and is being tagged."

This implies that the tag is already in the header of the packet as it reaches the router. The router, in this case, is not going to tag that traffic.

"...mean this is the default VLAN of 25 and is NOT being tagged?"

This native vlan configuration means that if there is no tag in the packet when it's received by the router/interface, it's going to tag it with VLAN 25.

You don't need to do any kind of VLAN'ing on the serial link (PPP). I would advise QoS/CoS though, if you have voice traffic traveling over that link.



So you're saying I have it just backwards?

I did see a post that said once you turn on 802.1q on the physical interface (to make it a Trunk port) and create the sub-interfaces, you have to designate one of the sub-interfaces as the "native" VLAN "which is where all untagged traffic will be tagged to."

Is that last statement what you mean?  I was understanding that to mean any traffic that is untagged coming into this interface is associated with the "native" VLAN.  Why would the router then tag it?
Sales & Systems Engineer
You don't have to set a native VLAN if all the traffic that you're sending to the interface in question is going to be tagged with the appropriate VLAN already.

A native VLAN is just to deal with traffic that is going to be received as untagged.

From your switches perspective you can make the interface that trunks to the Adtran a real trunk port as well, allowing both the VLAN's in question and you can make the other ports on your switch access ports on the appropriate VLAN so that those network endpoints are tagged by the switch with the appropriate VLAN.

For Example:

Interface 0/1 is dot1q
all subinterfaces are set for a particular VLAN, e.g. VLAN 11 and 25

Switch1 has port 1 connected to the Adtran on Interface 0/1, and it's also trunked to allow VLAN 11,25.
Client Device 1 which should be on VLAN 11 is connected to port 2 on the switch, so that switchport is an access port on VLAN 11.
Client Device 2 which should be on VLAN 25 is connected to port 3 on the switch, so that switchport is an access port on VLAN 25.

Make sense?



Yes, thank you.


Again, thank you for the clarification.

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