3Com 7757 Configuration Manual page 618

618 C 58: DHCP R
HAPTER
n
A C
ELAY GENT ONFIGURATION
Specifying address checking fields
After enabled with the address checking function, Switch 7750 Ethernet switches
default to check the IP address, MAC address, VLAN ID, and port number of a
DHCP client respectively. The DHCP client can access external networks only after
an entry matching all the four fields is found in the client address table.
You can disable some fields (MAC address, VLAN ID, or port number) from address
checking as needed. Thus, after enabled with address checking, the DHCP relay
agent will not check the disabled fields, so that the clients not matching all the
fields can also access external networks.
Table 490 Specify address checking fields
Operation
Enter system view
Enter interface view
Specify address checking
field(s)
Disable specified address
checking field(s)
If you configure a static client address entry on the DHCP relay agent using the
dhcp-security static command without specifying the vlan or port keyword, the
DHCP relay agent will not check the VLAN ID or port number when performing
address checking for the client, even if the two fields are enabled for address
checking.
Configuring dynamic entries
Through this configuration task, you can validate or invalidate the dynamic
IP-to-MAC mapping entries generated by the DHCP relay agent. DHCP client
addresses are matched based on the dynamic entries generated by DHCP relay
agent only after these entries are activated; otherwise, DHCP client addresses are
matched based only on the security address entries statically configured.
Table 491 Configure dynamic entries generated by DHCP relay agents
Operation
Enter system view
Enter VLAN interface
view
Validate the dynamic
entries generated by
the DHCP relay agent
Command
system-view
interface interface-type
interface-number
address-check field { mac | vlan |
port } enable
address-check field { mac | vlan |
port } disable
Command
system-view
interface interface-type
interface-number
address-check dhcp-relay
enable
Description
-
-
Optional
By default, after
enabled with the
address checking
function, the DHCP
relay agent checks the
IP address, MAC
address, VLAN ID, and
port number of a
DHCP client
respectively.
Description
-
-
Optional
By default, the dynamic IP-to-MAC
mapping entries generated by the
DHCP relay agent are valid