Page 2 of 2 - PXE Booting WinPE 2 - posted in Boot from LAN: I have the TFTP server installed and I can boot different WIM-images via the menu in the BCD file.

This happened in a SCCM 2012 R2 SP1 CU3 environment: When Deploying an OSD task sequence via PXE, at the PXE boot screen the client was stuck on PXE – TFTP Download: smsboot x64 pxeboot.n12. First thing I checked was the smspxe.log on the distribution point. I could see it was in a loop with the line “Looking for bootImage XXX00AA1” In the ConfigMgr console, I checked Monitoring Distribution Status Content Status and verified that the boot image was successfully distributed to the distribution point. It was, but obviously there is an issue. I went to Administration Overview Distribution Points and selected the distribution point having the issue, clicked on Content tab, typed in the boot image name or package ID and clicked Redistribute. Once the boot image had redistributed successfully, I cleared the PXE flag and PXE booted the client again.

It was able to successfully boot and run the Task Sequence.

The WDS TFTP service relies on a registry key HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/WDSServer/Providers/WDSTFTP/ReadFilter that controls which TFTP paths are mapped to the directory containing the various installation files defined by the RootFolder registry key in the same location. Depending on the existing configuration, it is likely that additional patterns must be added to make iPXE and the WDS boot programs work correctly.

Make sure the following patterns are included in the ReadFilter list: •. Once wdsnbp.com starts, it initiates a session with the WDS server that was specified in the DHCP next-server parameter. The session protocol uses a combination of DHCP requests and responses and TFTP to provide the client with the appropriate boot loader (such as bootmgr.exe or bootmgfw.efi) and boot configuration data (BCD). The wdsnbp.com program performs client architecture detection and reports it back to the server via the WDS session.

This session protocol uses DHCP as an RPC service endpoint, and the data passed back and forth (such as architecture information) is encoded in DHCP option 250. Together with option 252 (used by WDS to indicate BCD file name) and the DHCP file field (pointing the client to the next network boot program), the DHCP+TFTP negotiation completes the WDS session. If either wdsnbp.com or pxeboot.n12 gets stuck in a request loop, it is likely that the initial TFTP download worked, but subsequent ones are failing. Beneteau Oceanis 321 Manual more. This can happen because iPXE uses forward slashes in the TFTP file path, while the WDS boot programs are prone to using a mix of forward and backward slashes.

Make sure the WDS TFTP server's read filter has mapped the relevant path names. Inspect the use of slashes in the DHCP packets to see how they are used, and check that the ReadFilter registry setting is configured appropriately. The upside of chainloading WDS from iPXE is that it provides a fully working and isolated WDS setup, while iPXE remains in control as the initial boot program with WDS supplied as just another choice amongst the variety of alternate boot options. WDS remains in full control of its own configuration. A drawback with WDS is that it uses TFTP (although with extensions that allow larger receive windows), which is not nearly as fast as HTTP, especially if there is more than a few ms round-trip time between the client and server. This results in somewhat long loading times for large WIM images, particularly on links with medium to high latency. A good alternative to the PXE mechanism of WDS is, a boot loader that takes over the roles of wdsnbp.com and pxeboot.n12.

It lets you fetch all the relevant files over HTTP and hand over execution to bootmgr.exe. There is a drawback, however: Control over the dynamic BCD boot menu is taken away from WDS, as a static BCD file is served instead.