Technical data

from among identical routes the one with the lowest reference count. If there is
more than one lowest reference count, it uses the lowest use count.
Although ROUTED allows multiple default routes, it does not monitor interface
states. Conversely, GATED monitors interface status changes; however, it does not
allow multiple default routes.
For information about configuring dynamic routing with GATED, refer to the
Compaq TCP/IP Services for OpenVMS Management guide.
5.3 Remote Client Management (BOOTP/DHCP)
Dynamic Host Configuration Protocol (DHCP), a superset of the Bootstrap Protocol
(BOOTP), provides a centralized approach to the configuration and maintenance of
IPaddressspace.DHCPallowssystemmanagerstoconfigurevariousclientsona
network from a single location.
DHCP allocates temporary or permanent IP addresses from an address pool to
client hosts on the network. DHCP can also configure client parameters (such as
default gateway parameter), domain name server (DNS) parameters, and subnet
masks for each host running a DHCP client.
With DHCP, system managers can centralize TCP/IP network configurations and
management tasks involved with network connections. DHCP makes network
administration easier by allowing:
• Consistent application of network parameters, such as subnet masks and
default routers, to all hosts on a network
• Support for both DHCP and BOOTP clients
• Static (permanent) mapping of hardware addresses to IP addresses
• Dynamic (temporary) mapping of hardware addresses to IP addresses, where
the client leases the IP address for a defined length of time
_________________________ Note _________________________
An OpenVMS system running TCP/IP Services can be configured
as either a DHCP server or a client, but not as both. Moreover, do
not attempt to configure both BOOTP and DHCP; if you do, the
configuration generates a warning message.
In addition, the TCP/IP Services implementation of DHCP includes support for
DHCP server failover in an OpenVMS Cluster environment. For more information
about the OpenVMS Cluster environment, refer to Chapter 3.
As a superset of BOOTP functionality, DHCP offers robust configuration services,
including IP addresses, subnet masks, and default gateways.
DHCP is built on the client/server model in the following respects:
• The DHCP server is a host that provides initialization parameters.
• The DHCP client is a host that requests initialization parameters from a DHCP
server. A router cannot be a DHCP client.
5.3.1 How DHCP Operates
DHCP consists of two components:
• A mechanism for allocating network addresses to clients
5–6 Network Server Services