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Catalyst 2960 Switch Software Configuration Guide
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Chapter19 Configuring DHCP Features
Configuring DHCP Features
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-range 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 a port:
Switch(config)# ip dhcp snooping
Switch(config)# ip dhcp snooping vlan 10
Switch(config)# ip dhcp snooping information option
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# ip dhcp snooping limit rate 100
Enabling the DHCP Snooping Binding Database Agent
Beginning in privileged EXEC mode, follow these steps to enable and configure the DHCP snooping
binding database agent on the switch:
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
ip dhcp snooping database
{flash:/filename |
ftp://user:password@host/filename |
http://[[username:password]@]{hostna
me | host-ip}[/directory]
/image-name.tar |
rcp://user@host/filename}|
tftp://host/filename
Specify the URL for the database agent or the binding file by using one
of these forms:
• flash:/filename
• ftp://user:password@host/filename
• http://[[username:password]@]{hostname | host-ip}[/directory]
/image-name.tar
• rcp://user@host/filename
• tftp://host/filename
Step 3
ip dhcp snooping database timeout
seconds
Specify (in seconds) how long to wait for the database transfer process to
finish before stopping the process.
The default is 300 seconds. The range is 0 to 86400. Use 0 to define an
infinite duration, which means to continue trying the transfer indefinitely.
Step 4
ip dhcp snooping database write-delay
seconds
Specify the duration for which the transfer should be delayed after the
binding database changes. The range is from 15 to 86400 seconds. The
default is 300 seconds (5 minutes).
Step 5
end Return to privileged EXEC mode.
Step 6
ip dhcp snooping binding mac-address
vlan vlan-id ip-address interface
interface-id expiry seconds
(Optional) Add binding entries to the DHCP snooping binding database.
The vlan-id range is from 1 to 4904. The seconds range is from 1 to
4294967295.
Enter this command for each entry that you add.
Note Use this command when you are testing or debugging the switch.