3-11
Network diagram
Figure 3-8
Network diagram for DHCP-snooping Option 82 support configuration
Eth1/0/2
Client B
Switch
DHCP Snooping
Client A
Eth1/0/1
Client C
Eth1/0/3
Eth1/0/5
DHCP Server
Configuration procedure
# Enable DHCP snooping on the switch.
<Switch> system-view
[Switch] dhcp-snooping
# Specify Ethernet1/0/5 as the trusted port.
[Switch] interface Ethernet1/0/5
[Switch-Ethernet1/0/5] dhcp-snooping trust
[Switch-Ethernet1/0/5] quit
# Enable DHCP-snooping Option 82 support.
[Switch] dhcp-snooping information enable
# Set the remote ID sub-option in Option 82 to the system name (sysname) of the DHCP snooping
device.
[Switch] dhcp-snooping information remote-id sysname
# Set the circuit ID sub-option in DHCP packets from VLAN 1 to “abcd” on Ethernet 1/0/3.
[Switch] interface Ethernet1/0/3
[Switch-Ethernet1/0/3] dhcp-snooping information vlan 1 circuit-id string abcd
IP Filtering Configuration Example
Network requirements
As shown in
Figure 3-9
, Ethernet1/0/1 of the Switch 4210 is connected to DHCP server and
Ethernet1/0/2 is connected to Host A. The IP address and MAC address of Host A are 1.1.1.1 and
0001-0001-0001 respectively. Ethernet1/0/3 and Ethernet1/0/4 is connected to DHCP Client B and
Client C.
z
Enable DHCP snooping on the switch, and specify Ethernet1/0/1 as the DHCP snooping trusted
port.