HP-UX IP Address and Client Management Administrator's Guide HP-UX 11i v2, HP-UX 11i v3

network. The server is responsible for the pool of IP addresses and can give out an IP address
to a client requesting a new configuration from the pool of IP addresses for which it is responsible.
When a client requests for confirmation of its existing configuration, the server confirms the
configuration.
DHCP is a superset of the BOOTP bootstrap protocol. The DHCP server services the BOOTP
clients. And DHCP servers and clients from different vendors interoperate very well with one
another.
DHCP Clients
DHCP server supplies DHCP clients with sufficient information to establish an endpoint for
network communications. It also supplies other parameters required by the system- and
application-level software.
HP-UX workstations can run DHCP clients automatically. The autoparms script,
/sin/auto_parms, enables HP-UX systems to run DHCP clients automatically. The autoparms
script does not run, if you edit the configuration file /etc/rc.config.d/netconf.
DHCP clients can include TCP/IP network printers, X terminals, and Microsoft® Windows®
machines. In addition to supporting new DHCP clients, the DHCP server supports new and
existing BOOTP clients.
DHCP clients are currently supported on 10 BaseT and 100 BaseT ethernets. It is not supported
on FDDI and Token Ring networks.
DHCP Leases
The DHCP server controls the IP address block. It grants permission to DHCP clients to use IP
addresses on a lease basis. The IP address is leased to the client for a fixed amount of time. The
administrator sets the lease time, which can last from 120 seconds to infinity. During the lease
period, DHCP guarantees that the IP address assigned to the client is not reassigned to another
client.
Before the lease time expires, the DHCP client automatically requests an extension on its lease.
As long as the client can contact the DHCP server, the server renews the lease.
For example, when client A reboots, it attempts to renew the lease it had before being powered
off. If client A was powered off when the renewal time elapsed, it can be assigned a different IP
address. If the IP address is still unassigned when client A comes back online, the server can
assign the same IP address to client A. But if the server assigned the IP address to client B while
client A was offline, client A will be assigned a different IP address.
DHCP Transactions: Basic Operation
Figure 1-3 illustrates the interaction between the DHCP client and server.
DHCP Overview 45