HP 6125XLG R2306-HP 6125XLG Blade Switch Layer 3 - IP Services Configuration G - Page 59

Configuring the DHCP relay agent Overview The DHCP relay agent enables clients to get IP addresses from a DHCP server on another subnet. This feature avoids deploying a DHCP server for each subnet to centralize management and reduce investment. Figure 21 shows a typical application of the DHCP relay agent. Figure 21 DHCP relay agent application An MCE device serving as the DHCP relay agent can forward DHCP packets not only between a DHCP server and clients on a public network, but also between a DHCP server and clients on a private network. For more information about MCE, see MCE Configuration Guide. Operation The DHCP server and client interact with each other in the same way regardless of whether the relay agent exists. For the interaction details, see "Dynamic IP address allocation process." The following only describes steps related to the DHCP relay agent: 1. After receiving a DHCP-DISCOVER or DHCP-REQUEST broadcast message from a DHCP client, the DHCP relay agent fills the giaddr field of the message with its IP address and unicasts the message to the designated DHCP server. 2. Based on the giaddr field, the DHCP server returns an IP address and other configuration parameters in a response. 3. The relay agent conveys the response to the client. 50