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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
78-11380-12
Chapter 19 Configuring DHCP Features
Displaying DHCP Information
To disable DHCP snooping, use the no ip dhcp snooping global configuration command. To disable
DHCP snooping on a VLAN or range of VLANs, use the no ip dhcp snooping vlan vlan-id global
configuration command. To disable the insertion and removal of the option-82 field, use the no ip dhcp
snooping information option global configuration command. To configure an aggregation switch to
drop incoming DHCP snooping packets with option-82 information from an edge switch, use the no ip
dhcp snooping information option allow-untrusted global configuration command.
This example shows how to enable DHCP snooping globally and on VLAN 10 and to configure a rate
limit of 100 packets per second on Fast Ethernet port 0/1:
Switch(config)# ip dhcp snooping
Switch(config)# ip dhcp snooping vlan 10
Switch(config)# ip dhcp snooping information option
Switch(config)# interface fastethernet0/1
Switch(config-if)# ip dhcp snooping limit rate 100
Displaying DHCP Information
To display the DHCP snooping information, use one or more of the privileged EXEC commands in
Table 19-2:
Step 8
ip dhcp snooping limit rate rate (Optional) Configure the number of DHCP packets per second than an
interface can receive. The range is 1 to 4294967294. The default is no rate
limit configured.
Note We recommend an untrusted rate limit of not more than 100
packets per second. If you configure rate limiting for trusted
interfaces, you might need to increase the rate limit if the port is
a trunk port assigned to more than one VLAN on which DHCP
snooping is enabled.
Step 9
exit Return to global configuration mode.
Step 10
ip dhcp snooping verify mac-address (Optional) Configure the switch to verify that the source MAC address in
a DHCP packet that is received on untrusted ports matches the client
hardware address in the packet. The default is to verify that the source
MAC address matches the client hardware address in the packet.
Step 11
end Return to privileged EXEC mode.
Step 12
show running-config Verify your entries.
Step 13
copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose
Table 19-2 Commands for Displaying DHCP Information
Command Purpose
show ip dhcp snooping Displays the DHCP snooping configuration for a switch
show ip dhcp snooping binding Displays only the dynamically configured bindings in the DHCP snooping binding
database.
1
1. If DHCP snooping is enabled and an interface changes to the down state, the switch does not delete the manually configured bindings.
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