3Com 2928 User Guide - Page 308

1 DHCP Overview After the 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 configuration and centralized management. For details about the DHCP client configuration, refer to VLAN Interface Configuration. Introduction to DHCP 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 1-1, includes a DHCP server and multiple clients (PCs and laptops). Figure 1-1 A typical DHCP application 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 details about the DHCP relay agent configuration, refer to DHCP Relay Agent Configuration. DHCP Address Allocation Allocation Mechanisms DHCP supports three mechanisms for IP address allocation. 1-1