3Com 2928 - Baseline Plus Switch PWR, Руководство пользователя

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2-2
Figure 2-2
DHCP relay agent work process
As shown in
Figure 2-2 , the DHCP relay agent works as follows:
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 forwards the
message to the designated DHCP server in unicast mode.
2) 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
Advanced Parameters for the
DHCP Relay Agent
Required
Enable DHCP globally and configure advanced DHCP
parameters.
By default, global DHCP is disabled.
Creating a DHCP Server Group
Required
To improve reliability, you can specify several DHCP servers as
a 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.
Enabling the DHCP Relay Agent
on an Interface
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 default.
z
You can enable either the DHCP server or the DHCP relay
agent on an interface. The latest configuration takes effect.
z
The DHCP relay agent works on interfaces with IP
addresses manually configured only.