3Com 4210G Series - Displaying and Maintaining DHCP Snooping; DHCP Snooping Configuration Examples; DHCP Snooping Configuration Example

8-7
Displaying and Maintaining DHCP Snooping
To do… Use the command… Remarks
Display DHCP snooping entries
display dhcp-snooping [ ip
ip-address ]
Display Option 82 configuration
information on the DHCP snooping device
display dhcp-snooping
information { all | interface
interface-type interface-number }
Display DHCP packet statistics on the
DHCP snooping device
display dhcp-snooping packet
statistics [ slot slot-number ]
Display information about trusted ports display dhcp-snooping trust
Available in any
view
Clear DHCP snooping entries
reset dhcp-snooping { all | ip
ip-address }
Clear DHCP packet statistics on the DHCP
snooping device
reset dhcp-snooping packet
statistics [ slot slot-number ]
Available in
user view
DHCP Snooping Configuration Examples
DHCP Snooping Configuration Example
Network requirements
z As shown in Figure 8-3, Switch B is connected to a DHCP server through GigabitEthernet 1/0/1,
and to two DHCP clients through GigabitEthernet 1/0/2 and GigabitEthernet 1/0/3.
z GigabitEthernet 1/0/1 forwards DHCP server responses while the other two do not.
z Switch B records clients’ IP-to-MAC address bindings in DHCP-REQUEST messages and
DHCP-ACK messages received from trusted ports.
Figure 8-3 Network diagram for DHCP snooping configuration
Configuration procedure
# Enable DHCP snooping.
<SwitchB> system-view
[SwitchB] dhcp-snooping
# Specify GigabitEthernet 1/0/1 as trusted.
[SwitchB] interface gigabitethernet 1/0/1