Setting up DHCP Force Mode settings for UEFI hardware configuration with an Infoblox DHCP server so that clients can PXE boot.

Products

• Ghost Solution Suite

Issue/Introduction

In some instances it may be beneficial to use PXE Force Mode in a specific environment rather than the more standard usage of IP helpers on switches and routers for forwarding PXE traffic across subnets.  PXE Force Mode is an alternative to forwarding PXE traffic across subnets by configuring IP Helpers on switches and routers. If one is configured the other will not be used.

Support for making DHCP server changes needs to be provided by the DHCP server vendor.  The following information is intended to help with configuring those settings but does not replace the support from the DHCP server vendor. 
 

Environment

Deployment solution 7.x and 8.x 
Ghost Solution Suited 3.x
 

Cause

When setting up DHCP force mode the DHCP server is responsible for providing the information on which PXE server the client will work with and what file the PXE server will be delivering.  

When working in a mixed environment, meaning an environment with both BIOS/Legacy and UEFI clients then a different file needs to be delivered to the 2 different clients. 

For setting up the force mode settings for a UEFI system see below screen shots that show the settings that can be set up to direct your 64 bit UEFI clients to the BStrap\x64\Bstrap.efi file. 

 

Resolution

First set up Vender class identifiers for each architecture.   Below are the 3 boot up options and the file that each needs to point to.   

Bios/Legacy x86 & x64 vender-class-identifiers need to point to BStrap\x86\Bstrap.0 
PXEClient:Arch:00000

UEIF x86 vender-class-identifiers need to point to BStrap\x86\Bstrap.efi
PXEClient:Arch:00002
PXEClient:Arch:00006
 

UEFI x64 vender-class-identifiers need to point to BStrap\x64\Bstrap.efi
PXEClient:Arch:00007
PXEClient:Arch:00008
PXEClient:Arch:00009

 

Below is an example of the settings being applied to an Infoblox DHCP server for a UEFI x64 boot option. 

Adding the vender-class-identifiers.

Setting the DHCP Options that are needed.  Note the Option 43 settings may be different for UEFI and BIOS. 

Depending on what vender-class-identifiers is being set up point to the appropriate boot file. 
It is important on an Infoblox server to put the IP or Name of the PXE server in both the Next server and Boot server field.  

*Note: In at least one case of issues PXE booting with Infoblox DHCP, DHCP Snooping was required to be set to TRUST on the network ports for the PXE Sever. However, this may not be required for all PXE environments using Infoblox DHCP.

For more information on:

Microsoft PXE settings for mixed environments https://knowledge.broadcom.com/external/article?articleId=180935
Infoblox Documenation pages https://docs.infoblox.com/