Cisco IE-3000-8TC User Manual

23-7
Cisco IE 3000 Switch Software Configuration Guide
OL-13018-03
Chapter 23 Configuring DHCP Features and IP Source Guard
Configuring DHCP Snooping
DHCP Snooping Configuration Guidelines
These are the configuration guidelines for DHCP snooping.
• You must globally enable DHCP snooping on the switch.
• DHCP snooping is not active until DHCP snooping is enabled on a VLAN.
• Before globally enabling DHCP snooping on the switch, make sure that the devices acting as the
DHCP server and the DHCP relay agent are configured and enabled.
• When you globally enable DHCP snooping on the switch, these Cisco IOS commands are not
available until snooping is disabled. If you enter these commands, the switch returns an error
message, and the configuration is not applied.
– ip dhcp relay information check global configuration command
– ip dhcp relay information policy global configuration command
– ip dhcp relay information trust-all global configuration command
– ip dhcp relay information trusted interface configuration command
• Before configuring the DHCP snooping information option on your switch, be sure to configure the
device that is acting as the DHCP server. For example, you must specify the IP addresses that the
DHCP server can assign or exclude, or you must configure DHCP options for these devices.
• If the DHCP relay agent is enabled but DHCP snooping is disabled, the DHCP option-82 data
insertion feature is not supported.
Ta b l e 23-1 Default DHCP Snooping Configuration
Feature Default Setting
DHCP server Enabled in Cisco IOS software, requires configuration
1
1. The switch responds to DHCP requests only if it is configured as a DHCP server.
DHCP relay agent Enabled
2
2. The switch relays DHCP packets only if the IP address of the DHCP server is configured on the SVI of the DHCP client.
DHCP packet forwarding address None configured
Checking the relay agent information Enabled (invalid messages are dropped)
2
DHCP relay agent forwarding policy Replace the existing relay agent information
2
DHCP snooping enabled globally Disabled
DHCP snooping information option Enabled
DHCP snooping option to accept packets on
untrusted input interfaces
3
3. Use this feature when the switch is an aggregation switch that receives packets with option-82 information from an edge switch.
Disabled
DHCP snooping limit rate None configured
DHCP snooping trust Untrusted
DHCP snooping VLAN Disabled
DHCP snooping MAC address verification Enabled
DHCP snooping binding database agent Enabled in Cisco IOS software, requires configuration. This feature is
operational only when a destination is configured.

Cisco IE-3000-8TC Specifications

General

Brand	Cisco
Model	IE-3000-8TC
Category	Switch
Language	English