Cisco Systems 3750E manual Enabling Dhcp Snooping and Option, Interface range port-range, 22-12

Chapter 22 Configuring DHCP Features and IP Source Guard

Configuring DHCP Features

	Command	Purpose
Step 6
	interface range port-range	Configure multiple physical ports that are connected
		to the DHCP clients, and enter interface range
		configuration mode.
	or	or
	interface interface-id	Configure a single physical port that is connected to
		the DHCP client, and enter interface configuration
		mode.
Step 7
	switchport mode access	Define the VLAN membership mode for the port.
Step 8
	switchport access vlan vlan-id	Assign the ports to the same VLAN as configured in
		Step 2.
Step 9
	end	Return to privileged EXEC mode.
Step 10
	show running-config	Verify your entries.
Step 11
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

To remove the DHCP packet forwarding address, use the no ip helper-addressaddress interface configuration command.

Enabling DHCP Snooping and Option 82

Beginning in privileged EXEC mode, follow these steps to enable DHCP snooping on the switch:

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	ip dhcp snooping	Enable DHCP snooping globally.
Step 3
	ip dhcp snooping vlan vlan-range	Enable DHCP snooping on a VLAN or range of VLANs. The range is 1
		to 4094.
		You can enter a single VLAN ID identified by VLAN ID number, a series
		of VLAN IDs separated by commas, a range of VLAN IDs separated by
		hyphens, or a range of VLAN IDs separated by entering the starting and
		ending VLAN IDs separated by a space.
Step 4
	ip dhcp snooping information option	Enable the switch to insert and remove DHCP relay information
		(option-82 field) in forwarded DHCP request messages to the DHCP
		server. This is the default setting.
Step 5
	ip dhcp snooping information option	(Optional) Configure the remote-ID suboption.
	format remote-id [string ASCII-string	You can configure the remote ID to be:
	hostname]	• String of up to 63 ASCII characters (no spaces)
		• Configured hostname for the switch
		Note If the hostname is longer than 63 characters, it is truncated to 63
		characters in the remote-ID configuration.
		The default remote ID is the switch MAC address.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
22-12	OL-9775-02