To set up an IP helper on your Aruba switch, you can follow these steps:

Log in to your Aruba switch using an administrator account.

Navigate to the switch’s configuration interface.

Find the DHCP configuration section and locate the IP helper settings.

Add the IP address of your FOG imaging server to the IP helper configuration.

Specify the VLAN that the PXE boot requests will be sent on, which in your case is VLAN 100.

Redirect the PXE boot requests to the management VLAN, which in your case is VLAN 4.

Save the configuration and restart the switch if necessary.

To ensure that only PXE boot requests are redirected to the imaging server, you can configure the firewall rules on the switch. You can create a rule that only allows PXE boot traffic to be forwarded to the IP address of your imaging server.