CLI Reference Guide-R07

Chapter 9 | General Security Measures
DHCPv4 Snooping
– 293 –
switch receives any messages from a DHCP server, any packets received from
untrusted ports are dropped.
Example
This example enables DHCP snooping globally for the switch.
Console(config)#ip dhcp snooping
Console(config)#
Related Commands
ip dhcp snooping vlan (299)
ip dhcp snooping trust (302)
ip dhcp snooping
information option
This command enables the use of DHCP Option 82 information for the switch, and
specifies the frame format to use for the remote-id when Option 82 information is
generated by the switch. Use the no form without any keywords to disable this
function.
Note: Further optional details can be found in the following sub-command
descriptions:
◆ ip dhcp snooping information option encode no-subtype (294)
◆ ip dhcp snooping information option remote-id (296)
◆ ip dhcp snooping information option tr101 board-id (297)
Syntax
ip dhcp snooping information option
no ip dhcp snooping information option
Default Setting
Option 82: Disabled
DHCP Snooping Information Option Sub-option Format: extra subtype included
DHCP Snooping Information Option Remote ID: MAC Address (hex encoded)
Command Mode
Global Configuration
Command Usage
◆ DHCP provides a relay mechanism for sending information about the switch
and its DHCP clients to the DHCP server. Known as DHCP Option 82, it allows
compatible DHCP servers to use the information when assigning IP addresses,
or to set other services or policies for clients.