Reference Guide

ip dhcp relay
Enable Option 82.
C-Series, S-Series, Z-Series, S4810
Syntax
ip dhcp relay information-option [trust-downstream]
Parameters
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 8.3.11.1 Introduced on the Z9000.
Version 8.3.7.0 Introduced on the S4810.
Version 7.8.1.0 Introduced on the C-Series and S-Series.
ip dhcp snooping
Enable DHCP Snooping globally.
C-Series, S-Series, Z-Series, S4810
Syntax
[no] ip dhcp snooping
Defaults Disabled.
Command Modes CONFIGURATION
Command History
Version 8.3.11.1 Introduced on the Z9000.
Version 8.3.7.0 Introduced on the S4810.
Version 7.8.1.0 Introduced on the C-Series and S-Series.
Usage
Information
When enabled, no learning takes place until you enable snooping on a VLAN. After disabling
DHCP Snooping, the binding table is deleted and Option 82, IP Source Guard, and Dynamic ARP
Inspection are disabled.
Related
Commands
ip dhcp snooping vlan – enables DHCP Snooping on one or more VLANs.
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