H3C S9500 Series Operation Manual page 192

Operation Manual – Network Protocol
H3C S9500 Series Routing Switches
Caution:
The IP address of the intended DHCP server for the DHCP relay feature cannot be IP
address of the VLAN interface corresponding to the DHCP relay. Otherwise, the
system gives the information such as "
address on interface Vlan-interface 100!
II. Configure user address entries for a DHCP Relay
In a VLAN that has DHCP Relay configured, to enable a DHCP client using a legal fixed
IP address to pass the address checking of the DHCP security feature, you must add a
static address entry for the DHCP client. A static address entry indicates the relation
between a fixed IP address and a MAC address.
Perform the following configuration in system view.
Table 4-34 Configure user address entries for DHCP relay
Add a user address entry for DHCP
relay
Remove a user address entry for DHCP
relay
Note:
The DHCP client applies for an IP address through the DHCP relay. When the
packet from DHCP client passes the DHCP relay, the DHCP relay adds its primary
IP address in the packet and forwards the packet to the DHCP server. When
receiving the packet, DHCP server allocates an IP address in the same segment as
the IP address added by the DHCP relay.
Through the DHCP relay, the DHCP client only can obtain an IP address in the
same segment as the primary IP address of the DHCP relay.
III. Enable/Disable DHCP security on a VLAN interface
If you enable the DHCP security feature on a VLAN interface, the switch performs user
address checking on the VLAN interface to prevent unauthorized binding request. If
you disable the DHCP security feature on a VLAN interface, the switch does not
perform user address checking on the VLAN interface.
Perform the following configuration in VLAN interface view.
Operation
4-24
Chapter 4 DHCP Configuration
Can't set ip relay address as interface
".
Command
dhcp relay security
mac-address static
undo dhcp relay security ip-address
ip-address