Dhcp Snooping Configuration Guidelines - Cisco WS-CBS3032-DEL Software Configuration Manual

Chapter 22 Configuring DHCP Features and IP Source Guard
Table 22-1
Feature
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-13270-06
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.
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.
Before configuring the DHCP relay agent on your switch, make 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, configure DHCP options for devices, or set up the DHCP database agent.
If the DHCP relay agent is enabled but DHCP snooping is disabled, the DHCP option-82 data
insertion feature is not supported.
If a switch port is connected to a DHCP server, configure a port as trusted by entering the ip dhcp
snooping trust interface configuration command.
If a switch port is connected to a DHCP client, configure a port as untrusted by entering the no ip
dhcp snooping trust interface configuration command.
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
Default Setting
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.
Configuring DHCP Features
22-9