Dhcp Snooping Configuration Guidelines - Cisco 3750G - Catalyst Integrated Wireless LAN Controller Configuration Manual

Chapter 22 Configuring DHCP Features and IP Source Guard
Table 22-1
Feature
DHCP snooping enabled globally
DHCP snooping information option
DHCP snooping option to accept packets on
untrusted input interfaces
DHCP snooping limit rate
DHCP snooping trust
DHCP snooping VLAN
DHCP snooping MAC address verification
Cisco IOS DHCP server binding database
DHCP snooping binding database agent
1. The switch responds to DHCP requests only if it is configured as a DHCP server.
2. The switch relays DHCP packets only if the IP address of the DHCP server is configured on the SVI of the DHCP client.
3. Use this feature when the switch is an aggregation switch that receives packets with option-82 information from an edge

DHCP Snooping Configuration Guidelines

These are the configuration guidelines for DHCP snooping.
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OL-8550-02
Default DHCP Configuration (continued)
3
switch.
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
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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.
When configuring a large number of circuit IDs on a switch, consider the impact of lengthy character
strings on the NVRAM or the flash memory. If the circuit-ID configurations, combined with other
data, exceed the capacity of the NVRAM or the flash memory, an error message appears.
Default Setting
Disabled
Enabled
Disabled
None configured
Untrusted
Disabled
Enabled
Enabled in Cisco IOS software, requires
configuration.
The switch gets network addresses and
Note
configuration parameters only from a
device configured as a DHCP server.
Enabled in Cisco IOS software, requires
configuration. This feature is operational only
when a destination is configured.
Catalyst 3750 Switch Software Configuration Guide
Configuring DHCP Features
22-9