DHCP overview

The Dynamic Host Configuration Protocol (DHCP) provides a framework to assign configuration information to network devices.

DHCP uses the client-server model. Figure 266 shows a typical DHCP application.

A DHCP client can obtain an IP address and other configuration parameters from a DHCP server on another subnet through a DHCP relay agent. For more information about the DHCP relay agent, see "Configuring DHCP relay agent." You can enable the DHCP client on an interface. For more information about the DHCP client configuration, see "Configuring VLAN interface."

Figure 266 A typical DHCP application

DHCP address allocation

Allocation mechanisms

DHCP supports the following mechanisms for IP address allocation:

•Static allocation—The network administrator assigns an IP address to a client (for example, a WWW server), and DHCP conveys the assigned address to the client.

•Automatic allocation—DHCP assigns a permanent IP address to a client.

•Dynamic allocation—DHCP assigns an IP address to a client for a limited period of time, which is called a lease. Most DHCP clients obtain their addresses in this way.

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