R3166-R3206-HP High-End Firewalls Network Management Configuration Guide-6PW101

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DHCP overview
NOTE:
A
fter DHCP client is enabled on an interface, the interface can dynamically obtain an IP address and other
configuration parameters from the DHCP server. This facilitates user configuration and centralized
management. For detailed configuration, see the chapter “Interface management configuration.”
Introduction
The fast expansion and growing complexity of networks result in scarce IP addresses assignable to hosts.
Meanwhile, as many people need to take their laptops across networks, the IP addresses need to be
changed accordingly. Therefore, related configurations on hosts become more complex. The Dynamic
Host Configuration Protocol (DHCP) was introduced to solve these problems.
DHCP is built on a client-server model, in which a client sends a configuration request and then the server
returns a reply to send configuration parameters such as an IP address to the client.
A typical DHCP application, as shown in Figure 46, i
ncludes a DHCP server and multiple clients (PCs
and laptops).
Figure 46 A typical DHCP application
NOTE:
A
DHCP client can get an IP address and other configuration parameters from a DHCP server on another
subnet via a DHCP relay agent. For information about the DHCP relay agent, see the chapter “DHCP rela
y
agent configuration.”
IP address allocation mechanisms
DHCP supports three mechanisms for IP address allocation.
• Manual allocation: The network administrator binds an IP address to the MAC address of a client
like a WWW server, and DHCP conveys the IP address to the client according to the MAC address.
• Automatic allocation: DHCP assigns a permanent IP address to a client.