Multiple PXE Servers
TranslationCustomers pending..often need to operate multiple PXE servers on the same network. PXE services are used, e.g., for software distribution to Windows PCs or for IP phones. Even during major updates, it's useful to keep the existing openthinclient instance running unchanged while setting up a new version of the openthinclient Management Server in parallel.
Function of the openthinclient server
The openthinclient server includes several services that enable thin clients to boot via PXE over the network.
If PXE booting encounters issues, follow these troubleshooting steps.
Starting with version 2020.x, openthinclient also supports UEFI boot.
ProxyDHCP
To boot a thin client via PXE, configure the BIOS boot order so the first boot device is the network card. After powering on, the thin client sends a broadcast to the network and receives an IP address via unicast from the DHCP server. The ProxyDHCP service of the openthinclient server intercepts this information. That is, it recognizes the thin client’s MAC address and the IP address assigned by the DHCP server. In the openthinclient Manager, the system displays this thin client under “Unregistered Thin Clients.” If the MAC address belongs to a PC instead, the system requires no further action.
TFTP Service
If the MAC address is registered as a thin client in the openthinclient Manager, the TFTP service sends the boot file after the thin client communicates with the DHCP server, and the boot process begins. The thin client now boots via PXE.
White List
By default, openthinclient uses the whitelist method, so it serves the boot image only to thin clients that have been explicitly created with a name, location, and hardware type.
Other devices that attempt to boot via PXE appear in the list of unregistered thin clients, and the system defers serving them.
Multiple PXE Servers
Implement one of several approaches to enable multiple PXE servers.
VLANs
Provided that the appropriate switch hardware is available, use network management to divide the network into different segments. With Layer 2 switches, segment the TCP/IP network at the MAC address level; with Layer 3 switches, segment at the MAC or IP address level. This configuration places the broadcasts from the PXE clients and the associated PXE server within their own network segment.
Different DHCP Scopes
Organize PXE devices into different groups on the DHCP server. The DHCP server identifies the thin client by its MAC address. Then, set Options 66 and 67 on the DHCP server to direct each client to the appropriate PXE boot server.
All PXE servers use whitelists
With all PXE servers configured to use the whitelist method, register devices on the whitelist for other functions, e.g. software distribution and IP telephony. Ensure each PXE service identifies its MAC addresses through correct assignment.
PXE Server with Delay
Configure a delay for the PXE response in compatible software distribution services. In conjunction with the openthinclient server’s whitelist, configure the following:
After a client powers on, the openthinclient PXE service checks whether the MAC address is registered here. If so, it'll start the boot process. If the MAC isn't listed, the other PXE service will respond after the preset delay and provide the client with the boot file. This configuration ensures that all thin clients are explicitly registered with the openthinclient manager, and other devices boot from the software distribution on the same network after a short delay.
Multiple openthinclient Boot Servers
The techniques described above also apply to multiple openthinclient Management Servers. For major updates, it's advisable to keep the existing openthinclient instance unchanged, thereby maintaining live operations without disruption or downtime, following the “never touch a running system” principle.
At the same time, deploy a new version of the openthinclient Management Server. Now, comprehensive testing can be conducted using individual thin clients and pilot users. Create a checklist of items to test. This includes, for example: access to all terminal servers, passing USB drives between clients, multiple connected monitors, audio devices, network printers, smart card readers, etc. To set up thin clients on both the existing installation and the new installation, the easiest way is to change the first digit of the MAC address (additional information is available here).