VLAN 1 on Access port

[harmankardon]

I have an MX with a LAN setting of "VLANs" (as opposed to Single LAN) with only one VLAN configured, VLAN 1. All ports on the MX are configured as Trunk with native VLAN set to VLAN 1. 

I'd like to introduce a Voice VLAN to this network which I will add as VLAN 65 and leave the MX ports configured as they currently are.

The VoIP phones are all connected to a Meraki switch and the Meraki switch is connected to the MX. The phones all have a PC attached to them. The plan is to configure the ports on the Meraki switch as access ports and set the data and voice VLAN appropriately.

The rest of the network consists of unmanaged switches connected directly to the MX. So this network is currently flat with no VLAN tagging.

My question is about what happens when I set the data VLAN to VLAN 1 on the Meraki switch ports used by the phones. I know the switch will tag the phone traffic as VLAN 65 when it forwards phone traffic to the MX, but will it actually "tag" the data (PC) traffic as VLAN 1 when it forwards to the MX or does the switch know that VLAN 1 is the native (untagged) VLAN and leave it untagged?

Essentially trying to figure out if a Voice VLAN can be added without affecting the untagged nature of the current flat data network.

[RaphaelL]

The switch will tag the vlans according to the configuration of your trunks. 

If the native vlan is set to 1, it won't be tagged. I'm not sure if that was your question.

[harmankardon]

I probably haven't worded things clearly.

On the MX, all ports are trunk ports and the native VLAN for all ports is VLAN 1 which means VLAN 1 is untagged in the context of the MX.

If I set an access port on the Meraki switch to VLAN 1, when the switch forwards frames from this switch port to the MX, are these frames now tagged when the arrive at the MX? Or do they arrive untagged because VLAN 1 is the native (untagged) VLAN? If they do arrive tagged at the MX, does the MX then remove the tag before forwarding out on other ports?

[RaphaelL · Accepted solution]

It depends on the configuration on the MS. 

If the port between the MS and the MX on the MS side is set to trunk native 1 , it won't tag the packets on vlan 1. The MX will receive untagged packets it will end up in vlan 1.

You will have issues if the native vlan do not match , but the dashboard will alert you.

[harmankardon]

Thanks, this was the lightbulb moment for me.

[RaphaelL]

Glad we were able to assist you ! 🙂