Correlating A Dhcp Server Group With A Relay Agent Interface; Configuring The Dhcp Relay Agent Security Functions - H3C S5120-SI Series Configuration Manual

The address pool of the subnet to which the IP address of the DHCP relay agent belongs must be configured on the
DHCP server. Otherwise, the DHCP client cannot obtain a correct IP address via the DHCP relay agent.

Correlating a DHCP server group with a relay agent interface

This is a required task.
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.
To correlate a DHCP server group with a relay agent interface:
To do...
1. Enter system view
2. Create a DHCP server group
and add a server into the
group
3. Enter interface view
4. Correlate the DHCP server
group with the current interface
You can specify up to twenty DHCP server groups on the relay agent and eight DHCP server addresses for each
•
DHCP server group.
The IP addresses of DHCP servers and those of relay agent's interfaces cannot be on the same subnet.
•
Otherwise, the client cannot obtain an IP address.
A DHCP server group can correlate with one or multiple DHCP relay agent interfaces, while a relay agent
•
interface can only correlate with one DHCP server group.
Using the dhcp relay server-select command repeatedly overwrites the previous configuration. However, if
•
the specified DHCP server group does not exist, the interface still uses the previous correlation.
The group-id argument in the dhcp relay server-select command was specified by the dhcp relay
•
server-group command.

Configuring the DHCP relay agent security functions

Creating static bindings and enable IP address check
To avoid invalid IP address configuration, you can configure IP address check on the DHCP relay agent.
That is, the DHCP relay agent checks whether a requesting client's IP and MAC addresses match a
binding (dynamic or static) on the DHCP relay agent.
Use the command...
system-view
dhcp relay server-group
group-id ip ip-address
interface interface-type interface-
number
dhcp relay server-select
group-id
36
Remarks
—
Required
Not created by default.
—
Required
By default, no interface is
correlated with any DHCP server
group.