You might need to boot a system from the network under the following conditions:
When the system is first installed
If the system won't boot from the local disk
If the system is a diskless client
Two network configuration boot strategies are available:
Reverse Address Resolution Protocol (RARP) and ONC+ RPC Bootparams Protocol
Dynamic Host Configuration Protocol (DHCP)
For network devices, the process for booting over a local area network (LAN) and booting over a wide area network (WAN) is slightly different. In both network boot scenarios, the PROM downloads the booter from a boot server or an installation server, which is inetboot in this case.
When booting over a (LAN), the firmware uses RARP and BOOTP or DHCP to discover the boot or installation server. TFTP is then used to download the booter, which is inetboot in this case.
When booting over a WAN, the firmware uses either DHCP or NVRAM properties to discover the installation server, the router, and the proxies that are required for the system to boot from the network. The protocol that is used to download the booter is HTTP. In addition, the booter's signature might be checked with a predefined private key.
Any system can boot from the network, if a boot server is available. You might want to boot a stand-alone system from the network if the system cannot boot from the local disk. For information on changing or resetting the default boot device, see SPARC: How to Change the Default Boot Device by Using the Boot PROM.
Two network configuration boot strategies are available on sun–4u systems:
RARP – Reverse Address Resolution Protocol and ONC+ RPC Bootparams Protocol
DHCP – Dynamic Host Configuration Protocol
The default network boot strategy is set to RARP. You can use either protocol, depending on whether a RARP boot server or a DHCP boot server is available on your network.
Note - Sun Ultra systems must have at least PROM version 3.25.nn to use the DHCP network boot strategy. For information on determining your PROM version, see SPARC: How to Find the PROM Revision Number for a System.
If both protocols are available, you can temporarily specify which protocol to use in the boot command. Or, you can save the network boot strategy across system reboots at the PROM level by setting up an NVRAM alias. The following example uses the nvalias command to set up a network device alias for booting with DHCP by default on a Sun Ultra 10 system.
ok nvalias net /pci@1f,4000/network@1,1:dhcp
As a result, when you type boot net, the system boots by using DHCP.
Note - Do not use the nvalias command to modify the NVRAMRC file, unless you are very familiar with the syntax of this command and the nvunalias command. For information about using these commands, see the OpenBoot 3.x Command Reference Manual.
To boot with either protocol successfully, you must have already set up a RARP or DHCP boot server on your network.
ok boot net[:dhcp]
If you have changed the PROM setting to boot with DHCP by default, as in the preceding nvalias example, you only have to specify boot net.
ok boot net[:rarp]
Because RARP is the default network boot strategy, you only have to specify boot net:rarp if you have changed the PROM value to boot DHCP.