Administrator Guide

DHCP Snooping in a VLT Setup
In a VLT setup, the DHCP snooping binding table synchronizes between the VLT nodes. Similarly, the DAI and SAV tables also synchronize
between VLT nodes. For this feature to work in a VLT setup, make sure that DHCP relay, DHCP snooping, SAV, and DAI configurations
are identical between the VLT peer nodes.
Enabling DHCP Snooping
To enable DHCP snooping, use the following commands.
1. Enable DHCP snooping globally.
CONFIGURATION mode
ip dhcp snooping
2. Specify ports connected to DHCP servers as trusted.
INTERFACE mode
ip dhcp snooping trust
3. Enable DHCP snooping on a VLAN.
CONFIGURATION mode
ip dhcp snooping vlan name
Adding a Static Entry in the Binding Table
To add a static entry in the binding table, use the following command.
• Add a static entry in the binding table.
EXEC Privilege mode
ip dhcp snooping binding mac mac-address vlan-id vlan-id ip ip-address interface interface-
type interface-number lease lease-value
If multiple IP addresses are expected for the same MAC address, repeat this step for all IP addresses.
Clearing the Binding Table
To clear the binding table, use the following command.
• Delete all of the entries in the binding table.
EXEC Privilege mode
clear ip dhcp snooping binding
Displaying the Contents of the Binding Table
To display the contents of the binding table, use the following command.
• Display the DHCP snooping information.
EXEC Privilege mode
show ip dhcp snooping
• Display the contents of the binding table.
EXEC Privilege mode
show ip dhcp snooping binding
View the DHCP snooping statistics with the show ip dhcp snooping command.
View the DHCP snooping binding table using the show ip dhcp snooping binding command.
The following example output of the show ip dhcp snooping binding command displays that different IP addresses are mapped
to the same MAC address:
The following example shows a sample output of the show ip dhcp snooping binding command for a device connected to both
the VLT peers. The Po 10 interface is the VLT port channel connected to a ToR switch or an end device.
DellEMC#show ip dhcp snooping binding
Codes : S - Static D - Dynamic
IP Address MAC Address Expires(Sec) Type VLAN Interface
326
Dynamic Host Configuration Protocol (DHCP)