b.DHCP relay agent work process

As shown in b, the DHCP relay agent works as follows:

Table 81 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 forwards the message to the designated DHCP server in unicast mode.

Table 82 Based on the giaddr field, the DHCP server returns an IP address and other configuration parameters to the relay agent, which conveys them to the client.

DHCP relay agent configuration task list

Complete the following tasks to configure the DHCP relay agent:

Task

Remarks

Enabling DHCP and configuring

Required

 

advanced parameters for the DHCP

Enable DHCP globally and configure advanced DHCP parameters.

relay agent

By default, global DHCP is disabled.

 

 

 

 

Required

 

To improve reliability, you can specify several DHCP servers as a

Creating a DHCP server group

group on the DHCP relay agent and correlate a relay agent interface

with the server group. When the interface receives requesting

 

 

messages from clients, the relay agent will forward them to all the

 

DHCP servers of the group.

 

 

 

Required

 

Enable the DHCP relay agent on an interface, and correlate the

 

interface with a DHCP server group.

 

With DHCP enabled, interfaces work in the DHCP server mode by

Enabling the DHCP relay agent on an

default.

interface

IMPORTANT:

 

 

∙ You can enable either the DHCP server or the DHCP relay agent

 

on an interface. The latest configuration takes effect.

 

∙ The DHCP relay agent works on interfaces with IP addresses

 

manually configured only.

 

 

 

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