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DHCP CONFIGURATION
Some Concepts about
DHCP
DHCP Principles This is a world where networks are ever-growing in both size and complexity, and
the network configuration is getting more and more complex. As is often the case,
the number of hosts in a network exceeds that of the available IP addresses, and
position changes of hosts (when users carry their laptops from here to there, or
move to a wireless network) require reassigned new IP addresses. Dynamic host
configuration protocol (DHCP) is designed to accommodate this context. DHCP
adopts client/server model, where DHCP clients send requests to the DHCP server
dynamically and the DHCP server in turn returns corresponding configuration
information (such as IP addresses) according to the policies configured for it.
A typical DHCP implementation comprises a DHCP server and multiple DHCP
clients (PCs or laptops).
Figure 160 illustrates a network that employs DHCP.
Figure 160 Network diagram for DHCP
IP address assignment
1 IP address assignment policy
Different types of clients have different requirements for IP addresses. Servers
usually require long-term fixed IP addresses, some hosts may require automatically
assigned long-term fixed IP addresses, and some hosts may only require
dynamically assigned temporary IP addresses.
A DHCP server provides three policies to meet these requirements.
■ Manual IP address assignment. The administrator assigns fixed IP addresses to
DHCP clients that are of special uses, such as a WWW server.
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