Cisco Systems 3750E Enabling Dhcp Snooping on Private VLANs, Ip dhcp snooping database, 22-14

Chapter 22 Configuring DHCP Features and IP Source Guard

Configuring DHCP Features

Switch(config)# interface gigabitethernet2/0/1

Switch(config-if)#ip dhcp snooping limit rate 100

Enabling DHCP Snooping on Private VLANs

You can enable DHCP snooping on private VLANs. If DHCP snooping is enabled, the configuration is propagated to both a primary VLAN and its associated secondary VLANs. If DHCP snooping is enabled on the primary VLAN, it is also configured on the secondary VLANs.

If DHCP snooping is already configured on the primary VLAN and you configure DHCP snooping with different settings on a secondary VLAN, the configuration for the secondary VLAN does not take effect. You must configure DHCP snooping on the primary VLAN. If DHCP snooping is not configured on the primary VLAN, this message appears when you are configuring DHCP snooping on the secondary VLAN, such as VLAN 200:

2w5d:%DHCP_SNOOPING-4-DHCP_SNOOPING_PVLAN_WARNING:DHCP Snooping configuration may not take effect on secondary vlan 200. DHCP Snooping configuration on secondary vlan is derived from its primary vlan.

The show ip dhcp snooping privileged EXEC command output shows all VLANs, including primary and secondary private VLANs, on which DHCP snooping is enabled.

Enabling the Cisco IOS DHCP Server Database

For procedures to enable and configure the Cisco IOS DHCP server database, see the “DHCP Configuration Task List” section in the “Configuring DHCP” chapter of the Cisco IOS IP Configuration Guide, Release 12.2.

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	Specify the URL for the database agent or the binding file by using one
	{flash[number]:/filename	of these forms:
	ftp://user:password@host/filename	•	flash[number]:/filename
	http://[[username:password]@]{hostna
			(Optional) Use the number parameter to specify the stack member
	me host-ip}[/directory]
	/image-name.tar		number of the stack master. The range for number is 1 to 9.
	rcp://user@host/filename}	•	ftp://user:password@host/filename

tftp://host/filename

•http://[[username:password]@]{hostname host-ip}[/directory] /image-name.tar

•rcp://user@host/filename

•tftp://host/filename

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
22-14	OL-9775-02