Dhcp Snooping Configuration Guidelines; Configuring The Dhcp Server; Dhcp Server And Switch Stacks; Configuring The Dhcp Relay Agent - Cisco Catalyst 2960-XR Security Configuration Manual

Configuring DHCP
Feature
DHCP snooping binding database agent
2 The switch responds to DHCP requests only if it is configured as a DHCP server.
3 The switch relays DHCP packets only if the IP address of the DHCP server is configured on the SVI of the DHCP client.
4 Use this feature when the switch is an aggregation switch that receives packets with option-82 information from an edge switch.

DHCP Snooping Configuration Guidelines

• If a switch port is connected to a DHCP server, configure a port as trusted by entering the ip dhcp
• If a switch port is connected to a DHCP client, configure a port as untrusted by entering the no ip dhcp
• You can display DHCP snooping statistics by entering the show ip dhcp snooping statistics user EXEC

Configuring the DHCP Server

The switch can act as a DHCP server.
For procedures to configure the switch as a DHCP server, see the "Configuring DHCP" section of the "IP
addressing and Services" section of the Cisco IOS IP Configuration Guide, Release 12.4.

DHCP Server and Switch Stacks

The DHCP binding database is managed on the stack master. When a new stack master is assigned, the new
master downloads the saved binding database from the TFTP server. If the stack master fails, all unsaved
bindings are lost. The IP addresses associated with the lost bindings are released. You should configure an
automatic backup by using the ip dhcp database url [timeout seconds | write-delay seconds] global
configuration command.
When a stack merge occurs, the stack master that becomes a stack member loses all of the DHCP lease
bindings. With a stack partition, the new master in the partition acts as a new DHCP server without any of
the existing DHCP lease bindings.

Configuring the DHCP Relay Agent

Beginning in privileged EXEC mode, follow these steps to enable the DHCP relay agent on the switch:
OL-29434-01
snooping trust interface configuration command.
snooping trust interface configuration command.
command, and you can clear the snooping statistics counters by entering the clear ip dhcp snooping
statistics privileged EXEC command.
Catalyst 2960-XR Switch Security Configuration Guide, Cisco IOS Release 15.0(2)EX1
DHCP Snooping Configuration Guidelines
Default Setting
Enabled in Cisco IOS software, requires configuration.
This feature is operational only when a destination is
configured.
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