56 DHCP OVERVIEWWhen configuring ARP, go to these sections for information you are interested in:■ “Introduction to DHCP” on page 791■ “DHCP Address Allocation” on page 792■ “DHCP Message Format” on page 793■ “DHCP Options” on page 794■ “Protocols and Standards” on page 796Introduction to DHCP The fast expansion and growing complexity of networks result in scarce IPaddresses assignable to hosts. Meanwhile, with the wide application of wirelessnetworks, the frequent movement of laptops across networks requires that the IPaddresses be changed accordingly. Therefore, related configurations on hostsbecome more complex. Dynamic Host Configuration Protocol (DHCP) wasintroduced to solve these problems.DHCP is built on a client-server model, in which the client sends a configurationrequest and then the server returns a reply to send configuration parameters suchas an IP address to the client.A typical DHCP application, as shown in Figure 239, includes a DHCP server andmultiple clients (PCs and laptops).Figure 239 A typical DHCP applicationn When residing in a different subnet from the DHCP server, the DHCP client can getthe IP address and other configuration parameters from the server via a DHCPrelay agent. For information about the DHCP relay agent, refer to “Introduction toDHCP Relay Agent” on page 813.DHCP client DHCP clientDHCP client DHCP clientDHCP server
