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Ignite-UX Administration Guide: for HP-UX 11i > Chapter 4 Simple Network: Creating a Server for Anonymous ClientsConfiguring an Ignite Server to Boot Anonymous Itanium-Based Clients |
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Even on a simple network, there could be devices such as printers requesting network boot. This section describes the challenges involved and solutions for DHCP booting and then acquiring IP addresses for networking.
When an Itanium-based system boots over the network, it sends out a PXE boot request. The PXE protocol is built on top of DHCP. This can cause confusion if there is more than one DHCP server configured to respond to PXE boot requests. It is not possible for an Itanium-based system to specify the server from which to accept DHCP boot services, ignoring boot offers from all other servers. In other words, there is not an Itanium-based equivalent for the PA-RISC boot command, boot lan.192.10.10.10 install, which causes the system to ignore any response except from the IP address 192.10.10.10. This functionality is known as server selection. It is possible for many Itanium-based systems to perform directed boot, where server and client networking information is stored in client firmware and DHCP is not used. For more information on directed boot, see “Direct Boot Profiles for Itanium-Based Systems”. When an Itanium-based system sends out a PXE boot request, it tries to boot from the first PXE response it gets. If no PXE responses are received within a certain time, the system uses the first DHCP response it gets. If any of these responses are inadequate for network booting, the PXE boot attempt fails and an error message is displayed on the console of the requesting system. The information displayed with PXE errors is usually not explicit enough to determine the cause of the problem (see “Common Network Booting Errors”). For any network where there will be PXE boot requests from Itanium-based systems, only DHCP servers that can supply enough information for a successful boot should be configured to respond. If you have a DHCP server that responds to every DHCP request, regardless of whether it is a PXE request or not, it almost definitely interferes with PXE boot requests from Itanium-based servers. The boot request fails when a normal DHCP response is received in response to a PXE boot request. In addition to boot failure, the inability to select a boot server can lead to installation of the wrong operating system. Having PXE servers that respond with different boot content on the same network can cause confusion. For example, if there is a system supporting Linux boot and a system supporting HP-UX boot on the same network, they can each send a response to a PXE boot request, and the first server to respond will be used. It is not predictable which server would be used for boot. Interference with a PXE request from a DHCP server is a configuration issue on the DHCP server side. This issue is not specific to HP-UX or Ignite-UX, but rather is related to the way firmware performs a PXE boot. HP-UX 11i v3 and 11i v2 supports dhcp_device_group options that improve anonymous client DHCP booting for Itanium-based clients. The two configuration keywords re and ncid are used in a DHCP device pool group for this purpose. Make sure that at a minimum, HP-UX 11i v2 is installed on your Ignite-UX server or boot helper system. Add your device pool group entry to the /etc/dhcptab file on your Ignite-UX server or boot helper system. You should not need to restart bootpd if it is already running. When a new bootp DHCP request is received, bootp checks to see whether it must reread any configuration files. If you want to force bootp to reread the configuration file, send it the SIGHUP signal. The following example DHCP device group is the best way to support anonymous Itanium-based clients:
The options in the dhcp_device_group clause are:
With the device pool group added to the /etc/dhcptab file, your HP-UX 11i v2 or 11i v3 Ignite-UX server is now configured to respond to anonymous Itanium-based clients. Once Ignite-UX starts running, a DHCP request will be used to obtain an IP address used for installation or recovery if needed. Ignite-UX can be configured to specify a class-id for this request. For more information see Appendix B and bootpd(1M). If you have DHCP servers on your network that you have no control over, it is possible to completely isolate Ignite-UX from them. This is done by adding a class-id to the dhcp_class_id keyword in the install file system. See instl_adm(1M) and instl_adm(4) for additional information. When the network boot process completes and the install kernel is running, Ignite-UX will use DHCP again to obtain an IP address. This is done because Ignite-UX has no way to determine the IP address used by firmware. If you are running HP-UX 11i v2 or 11i v3 and have configured a DHCP device group for Itanium-based server PXE requests, you can reuse this device group for isolation purposes. If you added the following into the install file system: dhcp_class_id="IgniteDHCPDeviceGroup", you can change the class-id in the DHCP device group that responds to anonymous Itanium–based PXE boot requests to read: class-id="PXEClient:Arch00002|IgniteDHCPDeviceGroup" Since regular expression matching is used, | means "or" and allows response to an incoming class-id that matches either expression. This example entry would support responding to the initial Itanium-based system boot request as well as subsequent DHCP requests during Ignite-UX operation. The DHCP servers that respond to any DHCP class-id must be reconfigured or isolated to a different subnet. The information in this section will not help you isolate a system booting Ignite-UX from other DHCP or PXE boot servers when attempting to network boot from EFI. This information does help you stop other DHCP servers from communicating with the installed system after it has already performed a network boot and downloaded an install kernel and install file system. If you wish to only accept DHCP offers from a specific server after the install kernel and file system loads, consider using the dhcp_server keyword in the install file system. The use of the dhcp_server keyword has no effect on the EFI/PXE boot process. If your Itanium-based system is not running DHCP services, replacing the daemon bootpd with the daemon instl_bootd allows network booting for registered and anonymous clients, and both Itanium-based and PA-RISC clients. See Figure 2-2 “Decision Tree When Configuring a Server for Booting Itanium-Based Systems” and the subsequent discussions for more information. Using instl_bootd on an Ignite-UX server requires that the bootpd daemon is not running on the server. The instl_bootd daemon responds to all boot requests from clients. The instl_bootd daemon normally runs on a set of unique network ports, 1067/1068, which are used only for booting PA-RISC clients. However, in this implementation, the instl_bootd runs on the standard bootpd ports, 67/68. If you are running bootp with DHCP on your network, do not perform these steps. The instl_bootd daemon will answer DHCP requests as if the system were requesting a network boot. Consider other alternatives if you have bootp with DHCP running on your network. Follow these steps to configure your Ignite-UX server to run instl_bootd as a replacement for bootpd:
Your Ignite-UX server is now configured to respond to anonymous clients. For more information, see instl_bootd(1M) and inetd(1M). |
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