58 DHCP RELAY A GENT CONFIGURATIONWhen configuring the DHCP relay agent, go to these sections for information youare interested in:■ “Introduction to DHCP Relay Agent” on page 813■ “Configuration Task List” on page 815■ “Configuring the DHCP Relay Agent” on page 815■ “Displaying and Maintaining DHCP Relay Agent Configuration” on page 819■ “DHCP Relay Agent Configuration Example” on page 820■ “Troubleshooting DHCP Relay Agent Configuration” on page 821n ■ The DHCP relay agent configuration is supported only VLAN interfaces.■ DHCP Snooping must be disabled on the DHCP relay agent.Introduction to DHCPRelay AgentApplicationEnvironmentSince DHCP clients request IP addresses via broadcast messages, the DHCP serverand clients must be on the same subnet. Therefore, a DHCP server must beavailable on each subnet. It is not practical.DHCP relay agent solves the problem. Via a relay agent, DHCP clientscommunicate with a DHCP server on another subnet to obtain configurationparameters. Thus, DHCP clients on different subnets can contact the same DHCPserver for ease of centralized management and cost reduction.Fundamentals Figure 247 shows a typical application of the DHCP relay agent.
