Configuration manual

22-8
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-13270-03
Chapter 22 Configuring DHCP Features and IP Source Guard
Configuring DHCP Features
All snooping statistics are generated on the stack master. If a new stack master is elected, the statistics
counters reset.
When a stack merge occurs, all DHCP snooping bindings in the stack master are lost if it is no longer
the stack master. With a stack partition, the existing stack master is unchanged, and the bindings
belonging to the partitioned switches age out. The new master of the partitioned stack begins processing
the new incoming DHCP packets. For more information about switch stacks, see
Chapter 6, “Managing
Switch Stacks.”
Configuring DHCP Features
These sections contain this configuration information:
• Default DHCP Configuration, page 22-8
• DHCP Snooping Configuration Guidelines, page 22-9
• Configuring the DHCP Server, page 22-10
• DHCP Server and Switch Stacks, page 22-10
• Configuring the DHCP Relay Agent, page 22-11
• Specifying the Packet Forwarding Address, page 22-11
• Enabling DHCP Snooping and Option 82, page 22-12
• Enabling DHCP Snooping on Private VLANs, page 22-14
• Enabling the Cisco IOS DHCP Server Database, page 22-14
• Enabling the DHCP Snooping Binding Database Agent, page 22-15
Default DHCP Configuration
Table 22-1 shows the default DHCP configuration.
Ta b l e 22-1 Default DHCP Configuration
Feature Default Setting
DHCP server Enabled in Cisco IOS software, requires
configuration
1
DHCP relay agent Enabled
2
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
Disabled
DHCP snooping limit rate None configured
DHCP snooping trust Untrusted