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I was having issues getting a certain computer to download the boot image from my WDS server this morning, so I started doing some quick searches and ran across this MS article (ended up just being this model having a problem. Others worked fine). The article refers to using IP Helper address on my switches instead of using DHCP scope options 66 and 67. Because of this, I got curious and decided to try it out. I removed my scope options and added an IP helper for my WDS server (on top of my IP helper for the DHCP. Switches are HP Aruba). Unfortunately, this doesn’t appear to do anything and PXE is inoperable. The client gets its IP address and then hangs until PXE itself times out.

It’s a really simple environment for my test client as everything is on the same subnet! Per the MS article, this should work without me needing to do anything at all.

Personally, I’ve used the DHCP options for years. Before I used WDS/MDT, I was using Fog and have never had PXE issues stemming from the options. I’m curious about those of you that have got IP-Helper working for PXE as the “simple” method that I keep finding out online doesn’t appear to do anything in my environment. So for the time being, DHCP options are turned back on and everything works once again…

8 Spice ups
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If all you have is one subnet, the IP Helper on your switch won’t do anything. IP Helper is used when your DHCP server is on a different subnet than the machines it is needing to hand IP Addresses to. It allows your Layer 3 network switch to redirect the request for an IP from the client to the DHCP server on the other subnet.

Even when you use an IP Helper, you would still need to define any DHCP options that the clients need within the scope on the server.

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We do have multiple subnets which is the reasoning for the IP Helper. It’s just in the case of the machine I am testing with happens to be on the same subnet as both the DHCP server and WDS server. If I put the client on a different subnet, I’m not getting any changes, but that is to be assumed.

Regarding your last bit, that is kind of what I was figuring. That is why I am confused over Microsoft’s article. It seems like they’re suggesting the options should not be used at all, which many other sites saying the same thing and configuring WDS following that point. It just happens to be my first time seeing that. :slight_smile:

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There are standard DHCP options (3, 6, 15, etc.) that you’d still want to configure. The options specifically for PXE booting (60, 66, and 67) don’t need to be set when an IP helper is used with WDS. WDS has logic to handle this automatically.

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DHCP options (the PXE specific ones as BGM said) are not necessary and can be counterproductive. If WDS server is not running DHCP, look at the DHCP tab (in WDS properties) and be sure both boxes are NOT checked. WDS needs to listen on 67 to pick up the client request for a boot file.

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In addition to what Kevinhughes2 says, if DHCP and WDS are separate servers, configure IPhelper with the IP address of the DHCP server and the WDS server. You will be setting up two targets for IPhelper to talk to. WDS will not give a dhcp address but it does listen for clients and takes them on after they get an ip from the DHCP server. It’s a funny quirk.

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It is also important to make sure the WDS server is listed last.