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20-9
Catalyst 2960 and 2960-S Switch Software Configuration Guide
OL-8603-09
Chapter 20 Configuring DHCP Features and IP Source Guard Features
Configuring DHCP Snooping
Configuring DHCP Snooping
These sections contain this configuration information:
• Default DHCP Snooping Configuration, page 20-9
• DHCP Snooping Configuration Guidelines, page 20-9
• Configuring the DHCP Relay Agent, page 20-11
• Enabling DHCP Snooping and Option 82, page 20-11
• Enabling the DHCP Snooping Binding Database Agent, page 20-13
Default DHCP Snooping Configuration
Table 20-1 shows the default DHCP snooping configuration.
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.
Table 20-1 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.