Configuration Guide 558
Configuring Network Security DHCP Snooping Configuration
3.2.3 (Optional) Configuring Option 82
Option 82 records the location of the DHCP client. The switch can add the Option 82 to the
DHCP request packet and then transmit the packet to the DHCP server. Administrators can
check the location of the DHCP client via option 82. The DHCP server supporting Option 82
can also set the distribution policy of IP addresses and other parameters, providing more
flexible address distribution way.
Follow these steps to configure Option 82:
Step 1 configure
Enter global configuration mode.
Step 2 interface {
fastEthernet
port
| range fastEthernet
port-list
| gigabitEthernet
port |
range
gigabitEthernet
port-list
| interface port-channel
port-channel-id
| interface range
port-
channel
port-channel-id-list
}
Enter interface configuration mode.
Step 3 ip dhcp snooping information option
Enable the Option 82 feature on the port.
Step 4 ip dhcp snooping information strategy { keep | replace | drop }
Specify the operation for the Option 82 field of the DHCP request packets from the Host.
The following options are provided:
keep: Indicates keeping the Option 82 field of the packets.
replace: Indicates replacing the Option 82 field of the packets with one defined by switch.
By default, the Circuit ID is defined to be the VLAN and the number of the port which
receives the DHCP Request packets. The Remote ID is defined to be the MAC address of
the DHCP Snooping device which receives the DHCP Request packets.
drop: Indicates discarding the packets that include the Option 82 field.
Step 5 ip dhcp snooping information circuit-id
string
Configure the circuit ID. The circuit ID configurations of the switch and the DHCP server
should be compatible with each other.
string:
Enter the circuit ID, which contains up to 64 characters.
Step 6 ip dhcp snooping information remote-id
string
Configure the remote ID. The remote ID configurations of the switch and the DHCP server
should be compatible with each other.
string:
Enter the remote ID, which contains up to 64 characters.
Step 7 show ip dhcp snooping information interface { fastEthernet
port
| gigabitEthernet
port
|
port-channel
port-channel-id
}
Verify the Option 82 configuration of the port.
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