Reference Guide

ip dhcp relay
Enable Option 82.
C-Series, E-Series, S-Series, S4810
Syntax
ip dhcp relay information-option [remote-id | trust-downstream]
Parameters
remote-id Configure the system to enable the remote-id string in option-82.
trust-downstream Configure the system to trust Option 82 when it is received from the
previous-hop router.
Defaults Disabled
Command Modes CONFIGURATION
Command History
Version 8.3.7.0 Introduced on the S4810.
Version 8.3.1.0 Introduced on the E-Series.
Version 7.8.1.0 Introduced on the C-Series and S-Series.
ip dhcp snooping
Enable DHCP snooping globally.
C-Series, E-Series, Z-Series, S-Series
Syntax
[no] ip dhcp snooping
Defaults Disabled
Command Modes CONFIGURATION
Command History
Version 8.3.11.1 Introduced on the Z9000.
Version 8.3.1.0 Introduced on the E-Series.
Version 8.2.1.0 Introduced on the C-Series and S-Series on Layer 2 interfaces.
Version 7.8.1.0 Introduced on the C-Series and S-Series on Layer 3 interfaces.
Usage
Information
When enabled, no learning takes place until you enable snooping on a VLAN. After disabling
DHCP snooping, the binding table deletes and Option 82, IP Source Guard, and Dynamic ARP
Inspection are disabled.
Introduced in FTOS version 7.8.1.0, DHCP snooping was available for Layer 3 only and
dependent on DHCP Relay Agent (ip helper-address). FTOS version 8.2.1.0 extends
DHCP Snooping to Layer 2. You do not have to enable relay agent to snoop on Layer 2
interfaces.
673