Z3 to MR36 single LAN strange DHCP issue with VLAN 0

Mkozicki
Getting noticed

Z3 to MR36 single LAN strange DHCP issue with VLAN 0

So I have never seen anything like this and I know I can fix this by changing the Z3 to VLANs rather than Single LAN but I would rather just have it work right and I can't figure out why this is happening.

 

I am getting this error message on the MR36 that is plugged into the Z3.

 

This device is using a DHCP IP address from VLAN 0 instead of using configured VLAN 1.

 

Now this seems strange in the 1st place because of the VLAN 0 but I did try a few things.

 

1st on the AP I tried to change the LAN IP DHCP address option to VLAN 0 but as expected it will only let me pick from 1 to 4094 as I would expect.

 

So I went on Z3 under Appliance status then under DHCP and I see this.

 

 

DHCP subnets

Subnet VLAN

192.168.2.0/24192.168.2.0/24 - VLAN 0

 

 

Like I said under Addressing & VLANs this is set to Single LAN and the 192.168.2.0/24 is set up but I don't know how it's saying that it's on VLAN 0.

 

 

So question is how to I get the MR36 on VLAN 0 or the Z3 on VLAN 1 with the single LAN setup?  I know I can change this to VLANs but I would rather figure this out.

 

Or is this a BUG.

 

Thanks

Michael Kozicki
CCIE #5367
MJK Net Inc.
3 REPLIES 3
ww
Kind of a big deal
Kind of a big deal

Did you leave the vlan field  empty on the MR ?

Mkozicki
Getting noticed

When you pick single LAN I don't think it asks for a VLAN.  I may have to play with my lab box because my customer set this up and then asked me why he was getting the error message.

 

I did mess with my lab box and it does not seem to ask for a VLAN when you change it to single LAN.

Michael Kozicki
CCIE #5367
MJK Net Inc.
Bruce
Kind of a big deal

I’m thinking out loud here, but from memory the MR ports are always operating as a trunk (they don’t have an option to run as an access port), whereas when you put a MX into single VLAN mode all the ports are configured as access ports (since there is only one VLAN).

 

So I believe the error you may be seeing is because the MR is receiving a packet with no 802.1q header when it is expecting one, which leads back to what @ww said, which is make sure the VLAN field is empty on the MR’s management address configuration. With no VLAN configured on the MR management address it should assume the native VLAN (and so not expect the 802.1q tag).

 

If that still doesn’t work you might have to resort to some packet captures to see what’s going on.

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