MAC address pass through

I’ve started using a Plugable docking station which allows your USB-C MBP to use a wired connection on the dock. This works great except that your MBP gets assigned the IP address for the docking station’s ethernet port’s MAC address, which makes it impossible to switch between several different laptops. Each will get assigned the same IP address from a DHCP server that assigns IP addresses to MAC addresses, because the DHCP server only sees the docking station’s MAC address.

It might be possible to configure the DHCP server to assign IP addresses based on host names (not sure), but the other option would be to pass through a MAC address from the laptop to the docking station. It doesn’t seem like that’s supported by macOS 10.12 though. Anybody have any ideas for how to work around this limitation?

The docking station has its own MAC address hardwired to ethernet. That’s the MAC that the DHCP server assigns an IP address to. When I plug MBP #1 into the dock, I’ll see the dock show up in the list of available network interfaces. If I enable that, my MBP will get assigned that IP address on that interface.

Now I unplug MBP #1 and plug in MBP #2. As soon as I enable the dock’s network interface, the MBP will get assigned the same IP address (i.e. the one assigned to the dock’s MAC address). This causes a conflict.

For example, if that IP address is mapped to hostname ‘foo’, then things like ssh get into trouble because with MBP #1 connected, the IP address will have one host key, but with MBP #2 connected, that same IP address will have a different host key.

What I would like is for the DHCP server to see a different MAC address through the dock depending on which MBP is connected to it. I get that this may not at all be possible, either because of limitations in Network preferences or in the hardware/software configuration options of the dock. The dock’s manufacturer suggests that a “pass through” of a unique MAC address per machine to the dock is possible on Windows, so I’m kind of just throwing out a question as to whether the same is possible on macOS.

To answer your question, there is no built-in mechanism for Mac address Passthrough on a Surface 9 Pro. This means that the Surface will use the Mac address of the docking station when it is connected to it, and the Mac address of its own network adapter when it is not. This can cause some issues when you try to deploy a task sequence to an unknown computer using MECM, as the Surface may not be recognized by the MECM server.

One possible workaround for this issue is to manually add the Mac address of the Surface’s network adapter to the MECM database and assign it to the same device record as the docking station’s Mac address. This way, the MECM server will be able to identify the Surface regardless of whether it is docked or not.

Another possible workaround is to use a USB Ethernet adapter instead of the docking station and configure it to use a static Mac address that matches the Surface’s network adapter. This way, the Surface will always have the same Mac address when it is connected to the network, and the MECM server will be able to deploy the task sequence without any issues.

It’s useful only with a MS surface docking.
You have to activate in the BIOS the option : MAC Address Emulation. It’s on the Boot configuration page