Technical data
Configuring the DHCP Client
8.2 DHCP Client Components
There is one DHCP client process per system, even for multihomed hosts.
The DHCP client process is always running on a system that has an interface
designated under DHCP control. The DHCP client uses the OpenVMS
lock manager to prevent multiple DHCP client processes from executing
concurrently on a system. The resource name used to control the number of
client processes is TCPIP$DHCP_CLIENT_scsnode.
You stop this process by invoking the TCPIP$DHCP_CLIENT_SHUTDOWN
command procedure or by sending a DHCPSIGTERM to the process
using the TCPIP$DHCP_SIGNAL utility. Do not use the DCL command
STOP/IDENTIFICATION to stop this process.
To ensure proper termination of the DHCP client process, Compaq
recommends that you run the TCPIP$SHUTDOWN.COM procedure from
your site-specific shutdown procedure.
When a DHCP client process is not already executing, and you or the system
issues a DHCPCONF command, the system will automatically run the
DHCP client process. The TCP/IP command SET INTERFACE/DHCP and
the TCP/IP command START COMMUNICATION/INITIALIZE both invoke
DHCPCONF to start the DHCP client. Running TCPIP$DHCP_CLIENT_
STARTUP.COM will not itself create a DHCP client process.
• TCPIP$DHCP_CLIENT_CONF.EXE
This is the executable file for the DHCPCONF command, which is the UNIX
interface to the DHCP client. It communicates with the DHCP client process
to start the client, release a lease, drop the interface from control and other
requests.
Most users do not need to execute a DHCPCONF command directly. The
TCP/IP command SET INTERFACE/DHCP issues the necessary DHCPCONF
commands.
• TCPIP$DHCP_CLIENT_SHOWDHC.EXE
This is the executable file for the SHOWDHC command. This command
displays the data stored in an interface’s parameter file (
interface.DHC
).
Refer to Section 8.6 for a description of the commands supported by this
program.
8.2.2 Configuration Files
DHCP client uses the following files to control its environment:
• Configuration
• Interface
• Host name
• DHCPTAGS
8.2.2.1 Client Configuration File
DHCP client has one configuration file that controls DHCP client behavior. This
optional file, named CLIENT.PCY, is an ASCII file located in the DHCP home
directory, which is either SYS$SYSDEVICE:[TCPIP$DHCP] or a directory pointed
to by the system logical TCPIP$DHCP_CONFIG. If CLIENT.PCY does not exist,
DHCP client uses default values for each of the configurable parameters.
Configuring the DHCP Client 8–5