x86: About DHCP Macros

When you add clients with the add_install_client -d script on the install server, the script reports DHCP configuration information to standard output. You can use this information when you create the options and macros that are needed to pass network installation information to clients.

To install DHCP clients with a DHCP server over the network, you must create DHCP options. This information is needed to install the Oracle Solaris OS.

When a client sends a DHCP request, the server must have the following client information:

• Client's ID, which is typically the Ethernet address

• Class of the client request

• Subnet on which the client resides

The DHCP server forms a response. This response is based on the following macros, which matches the client request:

class macro

The class macro is based on a class string that is contained in the DHCP request. On x86 based systems, the BIOS already makes a DHCP request with the class PXEClient:Arch:00000:UNDI:002001. If a macro by this name is defined in the DHCP server configuration, then the macro content is sent to the x86 based clients.

network macro

The network macro is named by the IP address of the subnet that the client resides on. If the macro 129.146.87.0 is defined on the DHPC server, the macro content is sent to all clients on that subnet. The macro content is sent, regardless of the class of the request. If an option is defined in both the class macro and the network macro, the network macro takes precedence.

IP macro

The IP macro is named by an IP address. This macro is rarely used.

client macro

The client macro is named by the client type (01 for Ethernet) and the MAC address of the client, in uppercase letters. For a client with the Ethernet address 0:0:39:fc:f2:ef, the corresponding macro name is 01000039FCEF. Note the absence of colons in the client macro.

For example, for a client on the subnet 192.168.100.0, with the Ethernet address 0:0:39:fc:f2:ef, making a DHCP request of class PXEClient, the DHCP server has the following matching macro:

PXEClient
	BootSrvA:  192.168.100.0
	BootFile:  pxegrub
  129.146.87.0
	Router:    129.146.87.1
	NISdmain:  sunsoft.eng.sun.com
  01000039FCEF
	BootFile:  01000039FCEF
The actual DHCP response will be
	BootSrvA:  192.168.100.0
	BootFile:  01000039FCEF
	Router:    129.146.87.1
	NISdmain:  sunsoft.eng.sun.com

Note that the BootFile in the client macro overrides the BootFile in the class macro.

For more detailed information, see Preconfiguring System Configuration Information With the DHCP Service (Tasks) in Oracle Solaris 10 9/10 Installation Guide: Network-Based Installations.