Windows Image Deployment - Excluding MAC Addresses

There are a number of challenges when deploying desktop images with Microsoft System Center Configuration Manager (CM). One of the newer challenges is how to image a machine that does not have its' own internal ethernet interface.

CM does not have the ability to image a machine over a wireless adapter, so a "wired", ethernet network interface is required. Numerous external network interface solutions are available; typically manufacturers will offer an external docking station that provides the necessary network interface. This introduces the next challenge:

When an unknown computer is imaged with a CM Operating System Deployment (OSD) one of things that occurs is the computer is added to the Device Collections in CM. As part of this process, the MAC address of the computer is recorded as a property of the device. Once the MAC address is registered, it is no longer possible to image the machine, since it is no longer "unknown". This is due to the fact that OSD Task Sequences are typically deployed to the "All Unknown Computers" collection when hardware is imaged. The standard work-around to address this is to delete the device object in CM and then the device becomes "unknown" again and can then be reimaged.

This process fails when an external docking station needs to be used for imaging multiple machines. After the first time the docking station is used, the device is no longer "unknown". In the process of being added to the Device Collection in CM, the MAC address of the docking station is captured. Since this MAC address is now an element in the CM database, any device that is attached to it will not be considered "unknown", rendering a docking station only use-able once for imaging. Since having the just imaged machine in the Device Collection allows it to be managed, in this case deleting it is not a solution. Unless an organization is planning on purchasing a docking station for each device that does not have an internal Ethernet connector, this scenario proves problematic.

Fortunately, there is a relatively easy solution - add the MAC address(es) of the docking station(s) to an exclusion list for CM.

Example: The following example excludes the MAC address 94:9A:A9:27:A9:AB

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\COMPONENTS\SMS_DISCOVERY_DATA_MANAGER, ExcludeMACAddress

The Data entry field accepts multiple values, one per line. Add a carriage return after the last entry to prevent generating an error message.

Conclusion: Adding the MAC address exclusion allows a docking station to be used mulitple times for CM OSDs. Addtional testing demonstrated that the Device's properties in CM did not initially include any MAC address. However, after connecting with Wi-Fi and running a Hardware Inventory cycle, the MAC address of the Wi-Fi adapter was added to the Device's properties.

Author: Peter McDaniel, Lead Senior Consultant

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