Dell Z9000 Configuration Manual page 265

Dell Networking OS Behavior: Binding table entries are deleted when a lease expires or when the relay
agent encounters a DHCPRELEASE. Line cards maintain a list of snooped VLANs. When the binding table
is exhausted, DHCP packets are dropped on snooped VLANs, while these packets are forwarded across
non-snooped VLANs. Because DHCP packets are dropped, no new IP address assignments are made.
However, DHCPRELEASE and DHCPDECLINE packets are allowed so that the DHCP snooping table can
decrease in size. After the table usage falls below the maximum limit of 4000 entries, new IP address
assignments are allowed.
NOTE: DHCP server packets are dropped on all not trusted interfaces of a system configured for
DHCP snooping. To prevent these packets from being dropped, configure ip dhcp snooping
trust on the server-connected port.
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
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 contents of the binding table.
EXEC Privilege mode
show ip dhcp snooping
Dynamic Host Configuration Protocol (DHCP)
265