Problem with Windows Server 2019 DHCPv6 and Option 16 PXE boot

Hansjörg Schauffler 6 Reputation points


I need to define DHCP option 16 in Microsoft DHCPv6 server to
get UEFI clients to boot via PXE (to indicate to the UEFI clients that on the same server
there is a PXE service) . Unfortunately, the Microsoft DHCPv6 server
does not allow to define option 16 because option 16 belongs to the reserved predefined
options space. In the tiano core/edk2 (UEFI firmware reference) implementation
you can find that the UEFI client clearly expect option 16 back from the DHCPv6 server
in order to evaluate the response as PXE offer.

My question: Is there a way to force the Microsoft DHCPv6 server to return option 16
for UEFI clients in order to boot via a PXE? Or does the Microsoft DHCPv6 server not support PXE boot?


Windows Server
Windows Server
A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.
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Windows DHCP
Windows DHCP
Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.DHCP: Dynamic Host Configuration Protocol (DHCP). A communications protocol that lets network administrators manage centrally and automate the assignment of Internet Protocol (IP) addresses in an organization's network.
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  1. Limitless Technology 39,506 Reputation points


    if you are using the poredefined option The "Vendor Class ID" and "Bootfile Name" options in IPv6 can be added manually in the pre-defined options with Option Code 16(Vendor Class ID) and and 59(Bootfile Name). The typical network boot setup with DHCP service would look like

    Boot File 59
    Class Identifier 16 “HTTPClient”

    Besides the standard DHCP parameters like the station IP, gateway and DNS server address, the EDK II HTTP Boot driver will use the extensions below, assigned by the DHCP server in a corporate environment.

    1. Boot File: Tag (DHCPv4) 'file' field in DHCP header, or option 67 Tag # (DHCPv6): 59 Length:Varies Data Field:Boot File URI String
    2. Class Identifier: DHCPv4: 60 DHCPv6:16 Length:10 Data Field: "HTTPClient"

    Just for your understanding, Predefined options are the option codes defined in RFC 3315. You cannot redefine these options or delete them from the DHCP option space. Option codes 1-48 are reserved and cannot be used to define custom options.

    Custom options are option codes 49 to 254. They are not defined by IETF standards and are available for private use. You can use these option codes to provide configuration or service information that none of the predefined options provide.

    --If the reply is helpful, please Upvote and Accept as answer--