IP address assignment



  • We have our fog server on vlan 4 and the desktops we intend to image on vlan 100. Since the desktops are pxe booting into the fog server - does it get an IP address from the vlan 4 (fog server) or vlan 100 (default desktop subnet)?

    This is just a general question


  • Moderator

    @wreckignize The rest of the setup should be the same, just how it gets installed is different.



  • @george1421 ubuntu 18.04 - the command sudo apt-get install dnsmasq worked for me.


  • Moderator

    @wreckignize Sorry I was working on another issue. What OS is your FOG server running on? the yum command only works for centos and rhel.



  • @george1421 Question - how does one enable dnsmasq repo? I performed “sudo yum -y install dnsmasq” and it says there are no enabled repos.


  • Moderator

    @wreckignize I little bit longer explanation is that the aruba switch-dhcp doesn’t support dynamic boot loaders based on the target computer. The issue is that bios based computers require undionly.kpxe to boot and uefi computers take ipxe.efi to boot. You can’t mix up the boot loaders between the two firmware types. So with the aruba dhcp it only supports one boot loader name. So you can choose to either pxe boot bios or uefi based computers but not both without changing the boot loader configured in dhcp. Most companies need to support both types of firmware on their campus. So the aruba dhcp is insufficient for pxe booting both types at the same time. So in this case we are going to load a service on the fog server called dnsmasq. In this configuration the dnsmasq server is going to supply the pxe boot information only. The rest of the dhcp information will come from your dhcp server as normal. With this configuration if your fog server gets turned off then no pxe boot information will be given, but you need your fog server to pxe boot anyway so no loss or impact to your network.

    For the dnsmasq service to be able to “hear” the dhcp boot request on a remote subnet, your dhcp-relay service running on your vlan router will need to forward the dhcp request to both your main dhcp server and the fog server so both can respond correctly to support pxe booting.



  • @george1421 Thanks! I’ll get on this and update this thread when I see the result of the change.


  • Moderator

    @wreckignize said in IP address assignment:

    DHCP is handled by our core aruba switch.

    I will make a suggestion since you are using an aruba switch. Install dnsmasq on your fog server and configure your dhcp-helper service to include the FOG server’s IP address as the last server in the dhcp-helper service list.

    It should take no more than 10 minutes to setup dnsmasq just be sure to follow it exactly. You will need to get with your infrastructure folks to update the vlan router dhcp-helper service.
    https://forums.fogproject.org/topic/12796/installing-dnsmasq-on-your-fog-server


  • Moderator

    I agree with Sebastian, the answer is it depends…

    If you turn off the fog server, would the clients on vlan 100 still get an IP address? If so your dhcp server isn’t the fog server so your main dhcp server is still handing out IP addresses.

    If the clients on vlan 100 are not pxe booting (if that is the root of your question) , then you need to update your main dhcp server with dhcp options 66 and 67. Where dhcp option 66 is the IP address of your fog server and dhcp option 67 will be undionly.kpxe for bios computers or ipxe.eft for uefi based computers.



  • When the FOG server was setup it was a NO for the dhcp service. DHCP is handled by our core aruba switch. Hope that helps - 1st time using this tech.


  • Developer

    @wreckignize All depends on your setup. There is not much chance we can answer this not knowing how you setup FOG (yes or no when the installer asked to setup DHCP for you?) and the rest of your network.

    Maybe start explaining a bit more.


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