3Com Switch 7750 Configuration Guide

632 CHAPTER 59: DHCP SNOOPING CONFIGURATION
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■ Enable DHCP snooping and specify trusted ports on the switch before
configuring IP filtering.
■ You are not recommended to configure IP filtering on the ports of an
aggregation group.
Displaying and
Maintaining DHCP
Snooping
After the above configuration, execute the display command in any view to
display and verify the DHCP snooping configuration.
Execute the reset command in user view to clear the IP-MAC mappings recorded
by the DHCP-Snooping-enabled switch.
DHCP Snooping
Configuration
Example
DHCP Snooping Trusted
Port Configuration
Example
Network requirements
As shown in Figure 163, the Ethernet 2/0/1 port of Switch A is connected to
Switch B (acting as a DHCP relay agent). A network segment containing some
DHCP clients is connect to the Ethernet 2/0/2 port of Switch A.
■ The DHCP snooping function is enabled on Switch A.
■ The DHCP-Snooping-enabled device supports option 82 and option 82 is
enabled on the switch.
■ The Ethernet 2/0/1 port of Switch A is a trusted port.
Create a static binding ip source static binding
ip-address ip-address
[ mac-address mac-address ]
Optional
By default, no static binding
entry is created.
Table 505 Configure IP filtering
Operation Command Description
Table 506 Display and maintain DHCP snooping configuration
Operation Command Description
Display the IP-MAC mappings
recorded by the
DHCP-Snooping-enabled switch
display dhcp-snooping You can
execute the
display
command in
any view.
Display DHCP-Snooping status and
trusted port information
display dhcp-snooping trust
Display the total number of
DHCP-Snooping binding table entries
display dhcp-snooping count
Display the DHCP-Snooping binding
table entries of the specified VLAN
display dhcp-snooping
vlan { vlan-list | all }
Display IP static binding table entries display ip source static binding
[ vlan vlan-id | interface
interface-type interface-number ]
Clear the IP-MAC mappings recorded
by the DHCP-Snooping-enabled
switch
reset dhcp-snooping [ ip-address ] You can
execute the
reset command
in user view.