Cisco Catalyst 3560-X Series, Software Configuration Manual

Page: 664 / 1538

1-12
Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring DHCP Features and IP Source Guard
Configuring DHCP Features
To remove the DHCP packet forwarding address, use the no ip helper-address address interface
configuration command.
Enabling DHCP Snooping and Option 82
Beginning in privileged EXEC mode, follow these steps to enable DHCP snooping on the switch:
Step 6
interface range port-range
or
interface interface-id
Configure multiple physical ports that are connected
to the DHCP clients, and enter interface range
configuration mode.
or
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.
Command Purpose
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
[ smartlog ]
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.
• (Optional) Enter smartlog to configure the switch to send the
contents of dropped packets to a NetFlow collector.
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.