I'd like to set a dhcp option 77 string value in vsphere as a config parameter on a vm or vm template so that the vNIC ROM (e1000/vmxnet3) uses it during the DHCP part of PXE.

My goal is to have PXE booting nodes self identify using a dhcp option 77 string that I set, which then gets matched to a ISC dhcpd class which in turn provides specific settings during dhcp for that node. eg) dhcp opt 77 string value "foonode" maps to a dhcpd config class which sets a specific next-server.

I see that you can do this using iPXE as an optional boot rom for vmware (see here: http://ipxe.org/cfg/user-class and here: http://ipxe.org/howto/vmware), but I'd ideally like to do this by setting a configuration parameter for machines doing PXE using the normal vmware vNIC (e1000/vmxnet3) boot roms.

In a perfect world I could set these via the vsphere API.

1 Answer 1


iPXE approach is really a cowboy hack. The answer to your question is "No"; do not expect any standard PXE client (including VMware PXE ROMs) letting you set any DHCP option.


NIC boot-roms will only implement the DHCP options required by the PXE standard. What you are trying to do is not standard then you will not find any vendor willing to provide non-standard features in their PXE roms.

  • I wonder if while the DHCP options are settable, that perhaps NIC boot rom providers keep the features simple and don't implement support for them? I see that full OS's can do this like Windows and Linux. It is just that I was hopeful boot rom's would broadly support it as well.
    – Padge
    Aug 6, 2015 at 19:40
  • please see the answer edit.
    – Pat
    Aug 6, 2015 at 21:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.