H3C H3C S5100-SI, Operation Manual, Page: 350 / 830

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Task Remarks
Correlating a DHCP Server Group with a Relay Agent Interface Required
Configuring DHCP Relay Agent Security Functions Optional
Configuring the DHCP Relay Agent to Support Option 82 Optional
Correlating a DHCP Server Group with a Relay Agent Interface
To enhance reliability, you can set multiple DHCP servers on the same network. These DHCP servers
form a DHCP server group. When an interface of the relay agent establishes a correlation with the
DHCP server group, the interface will forward received DHCP packets to all servers in the server group.
Follow these steps to correlate a DHCP server group with a relay agent interface:
To do… Use the command… Remarks
Enter system view system-view —
Configure the DHCP server IP
address(es) in a specified
DHCP server group
dhcp-server groupNo ip
ip-address &<1-8>
Required
By default, no DHCP server IP
address is configured in a
DHCP server group.
interface interface-type
interface-number
Map an interface to a DHCP
server group
dhcp-server groupNo
Required
By default, a VLAN interface is
not mapped to any DHCP
server group.
z
You can configure up to eight DHCP server IP addresses in a DHCP server group.
z
You can map multiple VLAN interfaces to one DHCP server group. But one VLAN interface can be
mapped to only one DHCP server group.
z
If you execute the dhcp-server groupNo command repeatedly, the new configuration overwrites
the previous one.
z
You need to configure the group number specified in the dhcp-server groupNo command in VLAN
interface view by using the command dhcp-server groupNo ip ip-address& <1-8> in advance.
Configuring DHCP Relay Agent Security Functions
Configuring address checking
After relaying an IP address from the DHCP server to a DHCP client, the DHCP relay agent can
automatically record the client’s IP-to-MAC binding and generate a dynamic address entry. It also
supports static bindings, which means you can manually configure IP-to-MAC bindings on the DHCP
relay agent, so that users can access external network using fixed IP addresses.
The purpose of the address checking function on DHCP relay agent is to prevent unauthorized users
from statically configuring IP addresses to access external networks. With this function enabled, a
DHCP relay agent inhibits a user from accessing external networks if the IP address configured on the