SCCM PXE Responder and DHCP

One of the most eagerly awaited features of ConfigMgr Current Branch 1806 was the ability to enable PXE on Distribution Points without Windows Deployment Services (WDS). This was an enormous step forward as it can save customers money. I have customers with many PXE-enabled DPs throughout the world. That's a lot of server licensing. Previously a server OS was required simply for WDS. Now we can use a desktop operating system for the DP and enable it to use the lightweight PXE responder.

We were implementing this solution for a customer back in December and we had some trouble getting it to work. We were enabling the PXE responder on a server OS which may sound unusual but the customer was concerned about a possible reboot required for WDS and the logistics of organising this on 100 sites worldwide. It should still have worked - right?

The “Configmgr PXE responder service” was running successfully but we still saw this error in the SMSPXE.log file.

PXE: bind() failed for DHCP, 00:15:5D:05:16:00, 10.22.5.24, 67. 0x80072740.        SCCMPXE            12/20/2018 5:28:37 AM         6448 (0x1930)

This actually made sense as this server was also configured as a DHCP server. Of course that was the problem. Both DHCP and the PXE requests use port 67. This is ok when using WDS as we can configure it not to listen on port 67. Unfortunately we didn't have the same option with the PXE Responder.

I reported this to the product group on the 21st December. Other MVPs chimed in (thanks @jarwidmark) and talked about the merits of making this work. I'm pleased to say that this fix was released yesterday 23rd Jan in Technical Preview 1901, only a month later. That's an amazing turnaround for a feature. Hats off to @TweetKerwin and @djammmer and this shows the power of the ConfigMgr community. 

Details of the fix can be found in the TP1901 docs

When you enable a PXE responder on a distribution point without Windows Deployment Service, it can now be on the same server as the DHCP service. Add the following settings to support this configuration:

• Set the DWord value DoNotListenOnDhcpPort to 1 in the following registry key: HKLM\Software\Microsoft\SMS\DP
• Set DHCP option 60 to PXEClient
• Restart the SCCMPXE and DHCP services on the server.

Hopefully the fix will be available shortly in a production release.

I hope this helps. Until next time.....