I have 20 physical stations w/ 5 network drops at each station. All are connected via cascading switches to a central switch. On the switch are: an ASUS RT-N66U (semi)intelligent router with the embedded DHCP server handing out addresses to PC's at each of the station drops for the single WAN port for connecting to the Internet.

Also attached to the central switch is a proprietary Application/Server running Windows(c) 7 that has an embedded DHCP/TFTP server that has a proprietary application that responds to PXE boot requests from PC's to load and run the application.

I need to attach a any PC to any drop at any of the stations and have SOMEthing differentiate whether the PC is booting PXE and route to the Application Server DHCP/TFTP server or, if the PC is trying to go to the Internet, route to the ASUS router. These are randomly connected PC's and there is no way to differentiate or make unique the PC attached except for the MAC addresses.

I understand that there may be custom ports of ASUSWRT firmware (DDWRT or MerlinWRT) that 'may' do this, but I'd like to do this using existing firmware and hardware. I can do nothing about the proprietary server system. They've locked the code and will only support a dedicated network. I have a basic knowledge of TCP/IP, UDP DHCP/TFTP and know that DHCP/TFTP use UDP ports 67 and 68...

I'm thinking that there must be a routing statement I might add in the ASUS router that says, " Ah! You're a PXE boot agent PC! You go to the App.s server port 67/68 pair DHCP server" Or, "You're a Firefox browser PC! You want to get to the Internet through the ASUS router DHCP server!"

Any thoughts?

  • 1
    Holy wall of text batman! I gave up reading your question about half way through because it's too difficult to read as written. Perhaps some paragraphs would help. A diagram almost certainly would. – Iain Aug 18 '16 at 6:48

You can block DHCP traffic on Windows 7 with its local Windows Firewall and add PXE options on your other DHCP server if it's possible. So, everyone gets IP address and PXE information from a single server.

  • Good suggestion, but it doesn't apply in this case. To keep it simple, the App.s server running the embedded DHCP server needs to see the PXE booting PC's to get the application file to load to ROM on the PC. Win7 is only a platform for the App. server to run on. The Router is running full stack including it's embedded DHCP services. – BlaineM Aug 18 '16 at 15:39

Usually only one DHCP server is used in one network or subnetwork. It is possible to use several DHCP servers, but with special options (mac-address regular expressions or dhcp option 82), witch may be used to separate DHCP-clients between several servers. I recommend you to disable DHCP-server on your router.

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