Technical data

Configuring the DHCP Client
8.1 Key Concepts
3. DHCPCONF creates the DHCP client process.
If this is the first interface to be configured during the startup procedure,
DHCPCONF creates a detached process and runs the TCPIP$DHCP_
CLIENT_RUN.COM command procedure. TCPIP$DHCP_CLIENT_RUN
invokes the DHCP client image, TCPIP$DHCP_CLIENT.EXE. TCPIP$DHCP_
CLIENT continues to run until it is manually shutdown or the system
is shutdown. Therefore, if more than one interface is to be configured,
TCPIP$DHCP_CLIENT is ready to accept another DHCPCONF start
command.
4. DHCP client accepts the DHCPCONF start command.
DHCP client reads the start command and begins the DHCP dialog with the
server. DHCPCONF and the DHCP client use a simple UDP-based protocol to
communicate. If a HOSTNAME. file exists, the suggested host name is sent
to the server.
5. The DHCP client/server DHCP dialog completes.
DHCP client engages in a dialog with the DHCP server and when it completes
the DHCP client sets the interface’s IP address, subnet mask and broadcast
address by sending the information via an
ioctl to the TCP/IP kernel. If
the interface is designated as the primary interface then any system-wide
parameters received from the DHCP server are configured into the system.
6. DHCP client saves all parameters received from the DHCP server in a file
(interface.DHC). This step occurs even if the interface is not designated as the
primary interface.
7. DHCP client sends a task completion message to DHCPCONF to indicate that
the interface is initialized and ready for work.
8. The START COMMUNICATION/INITIALIZE command then repeats this
process for the next interface configured to be under DHCP control.
8.2 DHCP Client Components
The section describes the software and system elements that comprise DHCP
client including:
• Executable files
• Configuration files
• Command files
• System logical names
• Log files
8.2.1 Executable Files
Three programs comprise the DHCP client component:
• TCPIP$DHCP_CLIENT.EXE
This is the executable file for the DHCP agent or daemon. This process
engages in the DHCP protocol dialog with the DHCP server, receives the
parameters from the server and then configures the parameters on the local
system. The parameters include IP addresses and their lease information,
among others.
8–4 Configuring the DHCP Client