Client IP Conflict from MAC 00:00:00:00:00:00

Getting noticed

Client IP Conflict from MAC 00:00:00:00:00:00

Hey Gurus,


Installed a new POS system for a client. 100% Meraki MX, switches, and wireless. All POS devices are hard plugged directly into the Meraki switch (home runs) on the POS VLAN.


Customer called that POS terminals are having an issue. I login to Meraki and can ping all POS units with 0% packet loss, however when I check the event log I am seeing an IP Conflict. We reboot the POS units and the issue stops and the client IP conflict goes away. Randomly it starts again and the client IP conflict comes back, so I know for certain when client IP conflict happens the POS have issues.




Things we have tried:

- Removed dumb switch between Meraki & POS and ran dedicated home runs back to Meraki switch

- Used DHCP reservations, then removed them

- Turned off Meraki firewall IP Spoofing

- Upgraded firmware of switch and MX

- Ran cable tests on switch, confirmed no issues with drops


I called the POS vendor who said they want us to install the Zyxel router that came with the system. Frustrated they are making us do that because system requires no porting forwarding and only needs a specific VLAN with DHCP that is all. We are doing that now but want to see if anyone has seen this before and if they were able to fix it.

Kind of a big deal
Kind of a big deal

@IT_Magician not that I've seen this issue before but what EPoS system is it?  Do you have any other devices on the VLAN with the EPoS terminals, or just them?


We run a number of EPoS terminals on Meraki switches and haven't seen the same.

Kind of a big deal

@IT_Magician I would open a support ticket, the vendor asking you to use a different rotuer isn't really helpful unless they have past experience with issues with Meraki and this product. 

Meraki CMNO, Ruckus WISE, Sonicwall CSSA, Allied Telesis CASE & CAI

We are using Cake POS. They are saying it could be a "phantom" network, which sounds like something they have experienced and that is what they call it internally. All other devices on the POS network is printers. None of them are having these issues.

Kind of a big deal

00:00:00:00:00:00 is an invalid MAC address.  If any device is using this then it has a fault.  Most likely a hardware fault.  The manufacturer of the NIC has failed to burn in a MAC address to the device.

Kind of a big deal

An extreme option you might be able to use to work around the issue is to place each POS unit in its own dedicated L3 VLAN.

Get notified when there are additional replies to this discussion.
Welcome to the Meraki Community!
To start contributing, simply sign in with your Cisco account. If you don't yet have a Cisco account, you can sign up.