What is MAC Address Pass-through

Applies to:

• Latitude
• Mobile Precision Workstation
• XPS

Some network software applications, like Microsoft System Center Configuration Manager (SCCM) and other management tools, use a unique MAC address to grant network access or send software installations from a server.

Dell is solving a problem in the industry of USB-based Ethernet controllers. Dell has implemented a feature called MAC Address Override or MAC Address Pass Through that uses a system-unique MAC address entered in the system Basic Input/Output System (BIOS) which is then used to override the dock or dongle MAC address every time it is connected to the network. This way the network sees the system-unique MAC address. Dell systems using Dell Type-C USB network dongles and docks have a constant MAC Address no matter which USB Type-C adapter is connected to the system.

Dell Type-C USB network adapters including the Dell Adapter - USB-C to Ethernet (RJ45) dongle Dell DA200 Type-C Dock, The Dell Dock (WD15) and the Dell Thunderbolt Dock (TB16) all have their own MAC address built into their chipsets. When the dock/adapter is connected to a Dell system that supports MAC Pass-through, and the network driver is loaded on the system, the system specific MAC address from the BIOS overrides the adapter specific MAC address. This way the network consistently sees and uses the system specific MAC address.

Things to remember:

• This MAC Address Override feature is enabled using the BIOS and Network driver that resides in the operating system (Windows, Linux so forth).
• MAC Address Override does function before booting to the operating system and in the Preboot eXecution Environment (PXE) boot process.
• The system specific BIOS MAC address is listed in the BIOS so customers can view the MAC address without being in Windows.
• The MAC Address printed on the Dell dock label is not the MAC Address from the system BIOS.
• If the adapter/dongle is used on a Non-Dell system MAC Address override is not available, and the device uses the MAC address of the adapter/dongle only.

Also, see Dell Knowledge Base articles:

• MAC Address pass-through limitations for docked laptop systems

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