3com 8807 User Guide
Configuring DHCP Relay
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Note that the entire configuration procedure may goes through multiples times of
such interactions.
such interactions.
Configuring DHCP Relay
DHCP Relay configuration includes the following: The following text describes the
DHCP Relay configuration tasks:
DHCP Relay configuration tasks:
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Configuring a DHCP server for a VLAN interface
You can execute the ip relay address command to configure the DHCP packet
processing mode on VLAN interface as relay and a corresponding DHCP server for
a VLAN interface.
processing mode on VLAN interface as relay and a corresponding DHCP server for
a VLAN interface.
Perform the following configuration in VLAN interface view.
No DHCP server is configured for a VLAN interface by default.
Note that when configuring a new DHCP server for a VLAN that already has a
DHCP server configured for it, the newly configured one does not overwrite the
existing ones. Both the new and the old ones are valid. You can configure up to 20
DHCP server addresses for a VLAN interface.
DHCP server configured for it, the newly configured one does not overwrite the
existing ones. Both the new and the old ones are valid. You can configure up to 20
DHCP server addresses for a VLAN interface.
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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 "Can’t set ip relay address as
interface address on interface Vlan-interface 100!".
cannot be IP address of the VLAN interface corresponding to the DHCP relay.
Otherwise, the system gives the information such as "Can’t set ip relay address as
interface address on interface Vlan-interface 100!".
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.
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 or in VLAN interface view.
Table 650 Configure a corresponding DHCP server for a VLAN interface
Operation
Command
Configure a corresponding DHCP server for
current VLAN interface
current VLAN interface
ip relay address ip-address
Remove the DHCP server configured for
current VLAN interface
current VLAN interface
undo ip relay address { ip-address | all }
Table 651 Configure user address entries for DHCP relay
Operation
Command
Add a user address entry for DHCP relay
dhcp relay security ip-address mac-address
static
static
Remove a user address entry for DHCP relay
undo dhcp relay security ip-address