Configuring DHCP to support Legacy OSD

Owned by Martin Gudme Søndergaard
May 23, 2022
2 min read

Introduction

The following information is the description of how to configure DHCP to support OS Deployment with ciBoot in a Legacy BIOS boot scenario.


Element

Description

Settings for ciBoot

If the ciBoot service is running on the machine providing DHCP services, the following options must be set under Scope Options on the DHCP Server.
 
Option 60 Must specify the value PXEClient (the value is case-sensitive)
 
Microsoft does not provide option 60 by default in the DHCP setup, see below for instructions to create the value on a Microsoft DHCP server.

 How to configure Option 60

Step

Action

1

Open the DHCP management console

2

Right click the server node and select "Set Predefined Options..." and the follow windows appears.
 

3

Click Add... to open the following window
 

 
Specify the name, Data type and Code as shown.

4

Click OK to create the new Option Type.

5

Set the default value of the new Option Type to "PXEClient"
 

6

Click OK to save new Predefined Option

7

Option 60 is now available as both server option and scope option
 

Settings TFTPD service

To boot a client via PXE successfully, the following options must be set under Scope Options on the DHCP Server.
Option 66
Must point to a server having a TFTPD service available
Option 67
Must point to the boot image to load, in most cases this would point to \cipcc.0
 

Additional options used by OSD

Options 5 and 6 should also be specified to ensure functional DNS service in WinPE, otherwise the client can experience problems with locating the server.
If option 15 is not defined a dns surfix may be required for the network access credentials to work correctly.
Username=installuser@domain.local
Using the oldschool syntax domain\installuser will mostly not work in WinPE unless a running WINS service is available. Use option 44 to add a WINS server to the DHCP options.
 

DHCP/PXE models supported by OSD

Depending on the infrastructure provided and the availability and placement of DHCP servers, there a number scenarios to use when building DHCP/PXE environments.
One DHCP one PXE
The simple model where the DHCP doubles as the PXE server or simply refers to the PXE server by using 66
Many DHCP one PXE
Point all DHCP server to the IP of the server, OSD will automatically use the server address provided by DHCP
One DHCP many PXE
To use one PXE server from different DHCP servers or scopes, use option 66 to refer client to the server.
*Select PXE server manually from a list*
To manually select from a list of available PXE servers, built a number of copies of boot.wim and add additional menu linies to the cipcc.cfg file, each boot.wim should point to a specific servername in OSDLoader.ini.
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